Lanthanides chemistry and use in organic synthesis

Topics in Organometallic Chemistry Forthcoming volumes: Activation of Unreactive Bonds and Organic Synthesis Volume Editor: S.. Lanthanides: Chemistry and Use in Organic Synthesis Volum

Topics in Organometallic Chemistry

E d i t o r i a l B o a r d :

] M B r o w n P D i x n e u f A F i i r s t n e r L.S H e g e d u s

P H o f m a n n P K n o c h e l G v a n K o t e n T.] M a r k s

S M u r a i M R e e t z

Topics in Organometallic Chemistry

Forthcoming volumes:

Activation of Unreactive Bonds and Organic Synthesis

Volume Editor: S Murai

The Metal-Carbon Bond: Theoretical and Fundamental Studies Volume Editors: J.M Brown, E Hofmann

Lanthanides: Chemistry and Use

in Organic Synthesis

Volume Editor: S Kobayashi

With contributions by

R Anwander, E.C Dowdy, H Gr6ger, Z Hou, H Kagan,

S Kobayashi, G Molander, I.L Namy, M Shibasaki,

Y Wakatsuki, H Yasuda

~ Springer

The series Topics in Organometallic Chemistry presents critical overviews of re- search results in organometallic chemistry, where new developments are having a significant influence on such diverse areas as organic synthesis, pharmaceutical re- search, biology, polymer research and materials science Thus the scope of coverage includes a broad range of topics of pure and applied organometallic chemistry Cov- erage is designed for a broad academic and industrial scientific readership starting

at the graduate level, who want to be informed about new developments of progress and trends in this increasingly interdisciplinary field Where appropriate, theoreti- cal and mechanistic aspects are included in order to help the reader understand the underlying principles involved

The individual volumes are thematic and the contributions are invited by the vol- umes editors

In references Topics in Organometallic Chemistry is abbreviated

Top Organomet Chem and is cited as a journal

Springer WWW home page: http://www.springer.de

ISSN 1436-6002

ISBN 3-540-64526-8

Springer-Verlag Berlin Heidelberg New York

Cataloging-in-Publication Data applied for

Die Deutsche Bibliothek - CIP-Einheitsaufnahme

Lanthanides: chemistry and use in organic synthesis / vol ed.: S Kobayashi With contribution by R Anwander - Berlin ; Heidelberg ; New York ; Barcelona ; Budapest ; Hong Kong ; London ; Milan ; Paris ; Singapore ; Tokyo : Springer, 1999

(Topics in organometallic chemistry ; 2)

ISBN 3-540-64526-8

This work is subject to copyright All rights are reserved, whether the whole part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9,

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' Springer-Verlag Berlin Heidelberg 1999

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Prof Shfi Kobayashi

Graduate School of Pharmaceutical Sciences

The University of Tokyo

Hongo, Bunkyo-ku

Tokyo 113-0033, Japan

e-mail: skobayas@mol.f.u-tokyo.ac.jp

Editorial Board

Prof John M Brown

Dyson Perrins Laboratory

South Parks Road

Oxford OX1 3QY,

E-maih john.brown@chemistry.oxford.ac.uk

Prof Pierre Dixneuf Campus de Beaulieu Universit~ de Rennes 1

Av du G1 Leclerc F-35042 Rennes Cedex, France

E-maih Pierre.Dixneuf@univ-rennes 1.fr

Prof Alois Ftirstner

Max-Planck-Institut ftir Kohlenforschung

Kaiser-Wilhelm-Platz 1

D-45470 Miilheim an der Ruhr, Germany

e-mail: fuerst ner@mpi-muelheim.mpg.de

Prof Louis S Hegedus Department of Chemistry Colorado State University Fort Collins, Colorado 80523-1872, USA

Prof Gerard van Koten

Department of Metal-Mediated Synthesis

Debye Research Institute

E-maih knochel@psl 515.chemie.uni- marburg.de

Prof Tobin J Marks Department of Chemistry Northwestern University

2145 Sheridan Road Evanston, Illinois 60208-3113, USA

D-45470 Mfilheim an der Ruhr, Germany

E-maih reetz@mpi-muelheim.mpg.de

Preface

While the lanthanides (strictly defined as the 14 elements following lanthanum

in the periodic table, but as normally used also include lanthanum itself) have several unique characteristics compared to other elements, their appearance in the history of the development of organometallic chemistry is rather recent Since the f orbitals are filled gradually from lanthanum ([Xe]4f ) to lutetium ([Xe]4fl4), they are regarded as the f-block elements, which are discriminated from the d-block transition elements

This book was edited as the second volume of "Topics in Organometallic Chemistry", aiming at an overview of recent advances of chemistry and organic synthesis of lanthanides Since scandium (Sc) and yttrium (Y) (which lie above the lanthanides and have similar characteristics) are also included, this book covers rare earth chemistry Recently, especially in this decade, the chemistry and organic synthesis of lanthanides have developed rapidly as one of the most exciting areas An international team of authors has been brought together in order to provide a timely and concise review of current research efforts such as lanthanide catalysis in small molecule organic synthesis especially focused on carbon-carbon bond-forming reactions, chemistry and organic synthesis using low-valent lanthanides such as diiodosamarium, asymmetric catalysis, lantha- nide-catalyzed polymer synthesis, and polymer-supported lanthanide catalysts used in organic synthesis Principles of organolanthanide chemistry are summa- rized in the first chapter I am sincerely grateful to Drs R Anwander, E C Dow-

dy, H Gr6ger, Z Hou, H Kagan, G Molander, J L Namy, M Shibasaki, Y Waka- tsuki, and H Yasuda for participating in this volume J Richmond, J Sterritt- Brunner, and B Benner (Springer) are also acknowledged for encouraging me

to organize this work

Finally, I hope that this volume is helpful to many researchers and students who are or will be involved in or interested in this truly exciting and hot field

Principles in Organolanthanide Chemistry

R Anwander

Lanthanide Triflate-Catalyzed Carbon-Carbon Bond-Forming Reactions

in Organic Synthesis

S Kobayashi

Lanthanide- and Group 3 MetaUocene Catalysis in

Small Molecule Synthesis

G Molander, E C Dowdy

Influence of Solvents or Additives on the Organic Chemistry

Mediated by Diiodosamarium

H Kagan, ].L Namy

Chiral Heterobimetallic Lanthanoid Complexes: Highly Efficient

Multifunctional Catalysts for the Asymmetric Formation of C-C, C-O

and C-P Bonds

M Shibasaki, H Gr6ger

Reactions of Ketones with Low-Valent Lanthanides:

Isolation and Reactivity of Lanthanide Ketyl and

Ketone Dianion Complexes

Z Hou, Y Wakatsuki

Organo Rare Earth Metal Catalysis for the Living Polymerizations of

Polar and Nonpolar Monomers

Pr1nc1p1e51n 0r9an01anthan1de Chem15try

Re1ner A n w a n d e r

An0r9an15ch-chem15che5 1n5t1tut, 7echn15che Un1ver51tat M1Jnchen, L1chten- 6er95traf~e 4, D-85747 6arch1n9, 6 e r m a n y

e-ma1h r e 1 n e r a n w a n d e r c h t u m d e

Dur1n9 the 1a5t decade, the rare earth e1ement5 have 91ven en0rm0u5 5t1mu1u5 t0 the f1e1d 0f 0r9an1c 5ynthe515 1nc1ud1n9 5tere05e1ect1ve cata1y515.7h15 artMe 0ut11ne5 60th the 6a51c and advanced pr1nc1p1e5 0f the1r 0r9an0meta111c chem15try 7he 1ntr1n51c e1ectr0n1c feature5 0f th15 17-e1ement 5er1e5 are rev1ewed 1n 0rder t0 6etter under5tand the 5tructura1 chem15- try 0f the1r c0mp1exe5 and the re5u1t1n9 5tructure-act1v1ty re1at10n5h1p5 Part1cu1ar empha-

51515 p1aced 0n 5ynthet1c a5pect5,1.e 0pt1m12at10n 0f e5ta6115hed pr0cedure5 and a1ternat1ve meth0d5 w1th 6etter acce55 t0 cata1yt1ca11y re1evant 5pec1e5 Acc0rd1n91y, ta110r-made anc11- 1ary 119and5 are rep0rted 1n deta11 and the react1v1ty pattern 0f 1anthan1de c0mp0und515 ex- am1ned w1th repre5entat1ve examp1e5

Keyw0rd5: Lanthan1de5,1ntr1n51c pr0pert1e5, React1v1ty, 5ynthe515, L19and5

L15t 0f A66rev1at10n5

1 2 2.1 2.2 3 3.1 3.2 3.3 3.4 4 4.1 4.2 4.3 2 1ntr0duct10n 3

1ntr1n51c Pr0pert1e5 0f t h e L a n t h a n 1 d e E1ement5 4

E1ectr0n1c Feature5 4

5ter1c Feature5 7

5ynthe515 0 f 0 r 9 a n 0 1 a n t h a n 1 d e C 0 m p 0 u n d 5 8

7 h e r m 0 d y n a m 1 c a n d K1net1c 6u1de11ne5 9

1n0r9an1c Rea9ent5 10

Meta10r9an1c Rea9ent5 15

7 h e r m a 1 5ta6111ty 23

L19and C0ncept5 23

5ter1c 8u1k a n d D 0 n 0 r Funct10na112at10n 24

Anc111ary L19and5 27

1mm061112at10n - 5upp0rted L19and5 31

React1v1ty Pattern 0f 0r9an01anthan1de C0mp1exe5 32

5.1 D0n0r-Accept0r 1nteract10n5 32

5.2 C0mp1ex A9910mer12at10n 37

5.3 L19and Exchan9e and Red15tr16ut10n React10n5 39

5.4 1n5ert10n React10n5 41

5.5 E11m1nat10n React10n5- L19and De9radat10n 42

5.6 Red0x Chem15try 44

5.7 React10n 5e4uence5 - Cata1yt1c Cyc1e5 46

5.8 51de React10n5 47

Per5pect1ve5 50

Reference5 50

L15t 0f A66rev1at10n5

Ar

81N0L

CN

C 0 7

Cp

Cp*

DME

HMPA

H5A8

L

Ln

MMA

0 7 f

Ph

PMDE7A

Py

R

5a1en

7p

7HF

7MEDA

X

2

ar0mat1c re51due

61naphth01

c00rd1nat10n n u m 6 e r

cyc100ctatetraeny1

~15-cyc10pentad1enY 1

~15-PentamethY1cyc10pentad1enY 1

1,2-d1meth0xyethane

hexamethy1ph05ph0r1c tr1am1de

hard 50ft ac1d 6a5e

119and

1anthan1de (5c, Y, La, Ce-Lu)

methy1methacry1ate

tr1f1u0r0methane5u1f0nat0 ( tr1f1ate ), CF3503

pheny1

N, N, N ,N ,N -pentamethy1d1ethy1enetr1am1ne

pyr1d1ne

re51due

N,N -615( 3,5-d1-tert-6uty15a11cy11dene )ethy1ened1am1ne

tr15(pyra201y1)60rate

tetrahydr0furan

tetramethy1ethy1ened1am1ne

119and

nuc1ear char9e

Pr1nc1p1e51n 0r9an01anthan1de Chem15try

1

1ntr0duct10n

7he rare earth e1ement5 c0n5t1tute an 1nte9ra1 part 0f m0dern 0r9an1c 5ynthe515 [ 1 ] 1t wa5 a60ut 30 year5 a90 that the pecu11ar red0x 6ehav10r 0f 5evera11n0r9an1c rea- 9ent5 wa5 d15c0vered f0r 5e1ect1ve reduct1ve and 0x1dat1ve c0nver510n5 [2] 1n the 1n- ter1m per10d f1ne chem1ca15 and p01ymer 5ynthe515 have 1ncrea51n91y 6enef1ted fr0m the app11cat10n 0f h19h1y eff1c1ent 0r9an01anthan1de precata1y5t5 [3] Due t0 the1r 1ntr1n51c e1ectr0n1c pr0pert1e5 expre55ed 1n the 1anthan1de c0ntract10n , the rare earth e1ement5 c0mpr151n9 the 9r0up 3 meta15 5c,Y, La and the 1nner tran51t10n meta15 Ce-Lu pr0v1de new 5tructura1 and react1v1ty pattern5, emer91n9 1n 5truc- ture-act1v1ty re1at10n5h1p5 unprecedented 1n ma1n 9r0up and d-tran51t10n meta1 chem15try 1t 15 a150 the1r 10w t0x1c1ty and ava11a6111ty at a m0derate pr1ce wh1ch make5 th15 17-e1ement 5er1e5 attract1ve f0r 0r9an1c 5ynthe515 7he 5pectrum 0f rare earth rea9ent5 ran9e5 fr0m 1n0r9an1c t0 0r9an0meta111c c0mp0und5 a5 5che- mat1ca11y redrawn 1n F19 1 w1th repre5entat1ve examp1e5

Wh11e h19h1y eff1c1ent 1n0r9an1c rea9ent5 5uch a5 5m12(thf) 2 and 5c(07f) 3 are a1ready c0mmerc1a11y ava11a61e, the m0re 50ph15t1cated 0r9an0meta111c rea9ent5 are a5 a ru1e prepared 0n a 1a60rat0ry 5ca1e, 0ften under r190r0u5 exc1u510n 0f m015ture u51n9 1nert 9a5 techn14ue5 [4] 1n part1cu1ar, the 1atter c1a55 0f c0m- p0und5 0ffer5 acce55 t0 ta110r-made, we11-def1ned m01ecu1ar 5pec1e5 v1a 119and f1ne-tun1n9 7he c0n51derat10n 0f the 1ntr1n51c pr0pert1e5 0f the 1anthan1de cat1-

0n5 a5 we11 a5 therm0dynam1c and k1net1c fact0r5 are cruc1a1 1n de519n1n9 and 5ynthe5121n9 n0ve1 m01ecu1ar c0mp0und5.7h15 art1c1e a150 1nc1ude5 reference t0 h19h1y react1ve meta10r9an1c c0mp0und5, p5eud0-0r9an0meta111c5, c0nta1n1n9 n0 d1rect meta1 car60n 11nka9e; c0nta1n1n9, h0wever, 0therw15e read11y hydr0- 1y2a61e Ln-X 60nd5 F0r examp1e, 1anthan1de c0mp0und5 5uch a5 am1de and a1k0x1de der1vat1ve5 n0t 0n1y d15p1ay 1mp0rtant 5ynthet1c precur50r5 6ut a150 ex- h161t exce11ent cata1yt1c 6ehav10r 1n 0r9an1c tran5f0rmat10n5 [5,6] Macr0cyc11c 119and5 exh161t1n9 Ln-N and Ln-0 60nd5 are n0t c0n51dered 1n th15 5urvey [7] 7he 1a5t 20 year5 have w1tne55ed a rap1d deve10pment 1n 0r9an01anthan1de chem15try and numer0u5 rev1ew art1c1e5 have 6een pu6115hed, empha5121n9 var- 10u5 a5pect5 1nc1ud1n9 the1r u5e 1n 0r9an1c tran5f0rmat10n5 A c0mprehen51ve 115t 0f re1evant art1c1e5 ha5 6een 91ven recent1y [8] 7he purp05e 0f th15 art1c1e 15 n0t t0 91ve a c0mprehen51ve 5urvey 0f 0r9an01anthan1de c0mp0und5 6ut rather t0 addre55 the pr1nc1p1e5 0f the1r chem15try

2

1ntr1n51c Pr0pert1e5 0f the Lanthan1de E1ement5

7he rare earth e1ement5 repre5ent the 1ar9e5t 5u69r0up 1n the per10d1c ta61e and 0ffer a un14ue, 9radua1 var1at10n 0f th05e pr0pert1e5 wh1ch pr0v1de the dr1v1n9 f0rce f0r var10u5 cata1yt1c pr0ce55e5.7he1r pecu11ar e1ectr0n1c c0nf19urat10n and the c0nc0m1tant un14ue phy51c0chem1ca1 pr0pert1e5 a150 have t0 6e c0n5u1ted f0r the purp05e 0f 5ynthet1c c0n51derat10n5.7he h19h1y e1ectr0p051t1ve character 0f the 1anthan1de meta15, wh1ch 15 c0mpara61e t0 that 0f the a1ka11 and a1ka11ne earth meta15, 1ead5 a5 a ru1e t0 the f0rmat10n 0f pred0m1nant1y 10n1c c0m- p0und5, Ln(111) 6e1n9 the m05t 5ta61e 0x1dat10n 5tate [9] 7h15 and 0ther 1ntr1n- 51c pr0pert1e5 are 0ut11ned 1n 5cheme 1 wh1ch w111 5erve a5 a p01nt 0f reference 1n th15 5ect10n [10-13]

2.1

E1ectr0n1c Feature5

7he Ln(111) cat10n5 0f the 5er1e5 Ce-Lu exh161t the extended Xe-c0re e1ectr0n1c c0nf19urat10n [Xe]4f ~ (n=1-14), a 5ym601 wh1ch perfect1y p1cture5 the 11m1ted rad1a1 exten510n 0f the f-0r61ta15: 7he 4f5he1115 em6edded 1n the 1nter10r 0f the 10n, we11-5h1e1ded 6y the 552 and 5p 6 0r61ta15 [14] A p10t 0f the rad1a1 Char9e den- 51t1e5 f0r the 4f, 55, 5p and 65 e1ectr0n5 f0r 6d + v15ua11y exp1a1n5 why Ln(111) cat- 10n5 are c0mm0n1y th0u9ht 0f a5 a tr1p1e-p051t1ve1y char9ed c105ed 5he111nert9a5 e1ectr0n c10ud " (F19 2) [ 14]

10n12at10n ener91e5 0f the e1ement5 [ 15], 0pt1ca1 pr0pert1e5 [ 16], and ma9net- 1c m0ment5 0f numer0u5 c0mp1exe5 [ 17] pr0ve that the f-0r61ta15 are perfect1y 5h1e1ded fr0m 119and effect5 C0n5e4uent1y, 0n1y m1n1ma1 pertur6at10n 0f thef- e1ectr0n1c tran51t10n5 re5u1t5 fr0m the c0mp1exat10n 0f d1p01ar m01ecu1e5 1n c0ntra5t t0 the 6r0ad d~d a650rpt10n 6and5 0f the 0uter tran51t10n e1ement5, thef ff6and5 0f the 1anthan1de5 are a1m05t a5 narr0w 1n 5011d and 1n 501ut10n a5

Pr1nc1p1e51n 0r9an01anthan1de Chem15try

6 Reiner Anwander

they are for gaseous ions These transitions are “LaPorte-forbidden” and result

in weak intensities which are responsible for the pale color of the trivalent cies General principles of d-transiton metal ligand bonding such as σ-donor/π-acceptor interaction, the “18-electron rule”, and the formation of classiccarbene, carbyne, or carbon monoxide complexes are not observed in lantha-nide chemistry, neither do they form Ln=O or Ln≡N multiple bonds However,the lack of orbital restrictions, e.g the necessity to maximize orbital overlap as

spe-in d-transition metal chemistry, allows “orbitally forbidden” reactions Because

of very small crystal-field splitting and very large spin-orbit coupling (high Z)the energy states of the 4fn electronic configurations are usually approximated

by the Russel–Saunders coupling scheme [18] The peculiar electronic ties of the f-elements have proved attractive for numerous intriguing opto- andmagneto-chemical applications (“probes in life”) [15]

proper-The inert gas-core electronic configuration also implies a conform chemical behavior of all of the Ln(III) derivatives including Sc(III), Y(III) and La(III) Thecontracted nature of the 4f-orbitals and concomitant poor overlap with the lig-and orbitals contribute to the predominantly ionic character of organolantha-nide complexes The existing electrostatic metal ligand interactions are reflected

in molecular structures of irregular geometry and varying coordination bers According to the HSAB terminology of Pearson [19], lanthanide cations areconsidered as hard acids being located between Sr(II) and Ti(IV) As a conse-quence, “hard ligands” such as alkoxides and amides, and also cyclopentadienylligands show almost constant effective ligand anion radii (alkoxide: 2.21±0.03 Å;amide: 1.46±0.02; cyclopentadienyl: 1.61±0.03) [20] and therefore fit the evalua-tion criteria of ionic compounds according to Eigenbroth and Raymond [21].The ionic bonding contributions in combination with the high Lewis aciditycause the strong oxophilicity of the lanthanide cations which can be expressed interms of the dissociation energy of LnO [12] The interaction of the oxophilicmetal center with substrate molecules is often an important factor in governingchemo-, regio- and stereoselectivities in organolanthanide-catalyzed transfor-mations [22] Complexation of the “softer” phosphorus and sulfur counterions

num-is applied to detect extended covalency in these molecular systems [23,24].Scheme 1 further indicates the tendency of the Ln(III) cations to form themore unusual oxidation states in solution [25] Hitherto, organometallic com-pounds of Ce(IV), Eu(II), Yb(II) and Sm(II) have been described in detail [4].More sophisticated synthetic approaches involving metal vapor co-condensa-tion give access to lower oxidation states of other lanthanide elements [26].Charge dependent properties such as cation radii and Lewis acidity significantlydiffer from those of the trivalent species Ln(II) and Ce(IV) ions show very in-tense and ligand-dependent colors attributable to “LaPorte-allowed” 4f→5d

transitions [16b] Complexes of Ce(IV) and Sm(II) have achieved considerableimportance in organic synthesis due to their strongly oxidizing and reducing be-havior, respectively [1,27] Catalytic amounts of compounds containing the “hotoxidation states” also initiate substrate transformations As a rule this implies aswitch to the more stable, catalytically acting Ln(III) species [28]

Pr1nc1p1e51n 0r9an01anthan1de Chem15try

2.2

5ter1c Feature5

5tructura1 chan9e5 1n h0m01090u5 rare earth c0mp0und5 ar15e fr0m the 1antha- n1de c0ntract10n [29], 1.e the m0n0t0n1ca11y decrea51n910n1c rad11 w1th 1ncrea5- 1n9 at0m1c num6er 7he 4f-e1ectr0n5 added a10n9 the 1anthan1de 5er1e5 fr0m 1an- thanum t01utet1um d0 n0t 5h1e1d each 0ther eff1c1ent1y fr0m the 9r0w1n9 nuc1ear char9e, re5u1t1n91n the c0ntract10n phen0men0n 1t 15 0ften th15 vary1n9 cat10n- 1c 512e wh1ch ha5 a tremend0u5 effect 0n the f0rmat10n, c00rd1nat10n 9e0metry (c00rd1nat10n num6er5) and react1v1ty 0f the1r c0mp1exe5 Rep0rt5 have accu- mu1ated where 0r9an1c 5u65trate5 5eem t0 d15cr1m1nate n0t 0n1y 6etween 119and env1r0nment5 6ut a150 6etween 51n91e 1anthan1de e1ement5 [22] 5ucce55fu1 ex- p1anat10n5 0f the5e phen0mena are 6a5ed 0n the 5y5temat1c the0ret1ca11nve5t1- 9at10n and 5tructura1 character12at10n 0f 0r9an01anthan1de c0mp0und5 [4] 5cheme 1 91ve5 the trend 0f 10n1c rad11 0f the5e 1ar9e cat10n5 wh1ch prefer f0rma1 c00rd1nat10n num6er5 1n the ran9e 0f 8-12 [30] F0r examp1e, c0n51der- 1n9 the effect1ve Ln(111) rad11 f0r 6-c00rd1nat10n, a d15crepancy 0f 0.171 ~ 6e- tween Lu(111) and La(111) a110w5 the 5ter1c f1ne-tun1n9 0f the meta1 center [11] 7he 5tructura11mp11cat10n5 0f the 1anthan1de c0ntract10n are 111u5trated 1n F19 3 w1th the we11-exam1ned h0m01ept1c cyc10pentad1eny1 der1vat1ve5 [31] 7hree 5tructure type5 are 065erved depend1n9 0n the 512e 0f the centra1 meta1 at0m: A, [(r15-Cp)2Ln(6t-r15:r1x-Cp)]00 1-<x-<2; 8, Ln(r15-Cp)3; C, [(r15-Cp)2Ln(6t-r11:r11- Cp)]00; the5e exh161t c00rd1nat10n num6er5 0f 11 (10), 9, and 8, re5pect1ve1y 1n

acc0rd w1th 10n1c 60nd1n9, 5ma11 chan9e51n 119and 5u65t1tut10n 1ead t0 chan9ed c00rd1nat10n 6ehav10r and num6er (CN=10), a5 f0und 1n the tetranuc1ear r1n9 5tructure 0f the MeCp der1vat1ve M0n0mer1c type 8 15 preferent1a11y f0rmed w1th 119and5 6ear1n9 6u1ky 5u65t1tuent5

H19h c00rd1nat10n num6er5 can u5ua11y 6e acc0mp115hed 1n 01190mer1c 5truc- ture5 0r h19h1y 501vated c0mp1exe5 H0wever, 60th f0rm5 are unde51ra61e f0r 5ynthe5121n9 h19h1y react1ve c0mp0und5.7he react1v1ty and 5ta6111ty, re5pect1ve- 1y, 0f 1anthan1de c0mp1exe5 15 c0rre1ated w1th the 5ter1c 51tuat10n at the meta1 center Eva1uat10n cr1ter1a a5 the pr1nc1p1e 0f 5ter1c 5aturat10n/un5atura- t10n/0ver5aturat10n have 6een deve10ped t0 exp1a1n the d1fference5 1n react1v1ty [32] Hence, the ma1n 5ynthet1c eff0rt5 a5 1n d-meta10r9an1c chem15try are put 1nt0 the f1ne-tun1n9 0f the 119and 5phere t0 06ta1n tracta61e (v01at11e, cata1yt1ca1- 1y react1ve, etc.) c0mp0und5.8ecau5e 0f the 1mp0rtance 0f 5ter1c fact0r5,119and env1r0nment5 have 6een numer1ca11y re915trated, e.9 6y the c0ne-pack1n9 m0de1 [33], wh1ch repre5ent5 a 3-D exten510n 0f 701man 5 c0ne-an91e m0de1 [34] 1n th15 m0de1, 5011d an91e5 are ca1cu1ated fr0m 5tructura1 data emp10y1n9 van der Waa15 rad11 [35] and c0n51der1n9 effect5 0f 5ec0nd 0rder pack1n9 7he 1n- tr0duct10n 0f 5ter1c c00rd1nat10n num6er5 f0r var10u5 type5 0f 119and5 6a5ed 0n 5011d an91e rat105 further empha512e5 the 1mp0rtance 0f 5ter1c c0n51derat10n5 1n 0r9an0-f-e1ement chem15try [36]

7he Lew15 ac1d1ty wh1ch 15 affected 6y the char9e den51ty (2/r) 15 1e55 d15t1nct 1n c0mp1exe5 der1ved fr0m the 1ar9e Ln(111) cat10n5 Hence, the5e 5y5tem5 are 0f- ten rep0rted a5 m11d Lew15 ac1d1c cata1y5t5 1n 0r9an1c 5ynthe515 [1] H0wever, 5c(111) a5 6y far the 5ma11e5t Ln(111) cat10n 1510cated 1n a p01e p051t10n n0t 0n1y w1th re5pect t0 Lew15 ac1d1ty 1t5 a1um1num/1anthan1de/ear1y tran51t10n meta1 hy6r1d character [37] ha5 revea1ed 1t5 5uper10r1ty 1n many cata1yt1c app11cat10n5 [37,38] 8a5ed 0n the1r re1at1ve preference5 f0r pyr1d1ne, Lappert 5u99e5ted a re1- at1ve Lew15 ac1d1ty 5ca1e: Cp25cMe>A1Me3>Cp2YMe-~Cp2LnMe (here: Ln=1ar9e 1anthan1de e1ement5) [39] Max1mum e1ectr05tat1c meta1/119and 1nteract10n and 10n1c 60nd 5tren9th (enhanced c0mp1ex 5ta6111ty) 15 a150 expected f0r 5cand1um, the 5ma11e5t e1ement 7he Ln(111) char9e den51ty and the c0nc0m1tant c0mp1ex- at10n tendency a150 pr0ve u5efu1 when 5tudy1n9 the nature 0f C a 2+ 61nd1n91n 61- 01091ca1 macr0m01ecu1e5 exp101t1n9 the 1anthan1de e1ement5 a5 5pectr05c0p1c and ma9net1c pr06e5 [15]

3

5ynthe515 0f 0r9an01anthan1de C0mp0und5

7he ava11a6111ty 0f pure and we11-def1ned 5tart1n9 mater1a15 15 cruc1a1 f0r 5tra19htf0rward and h19h-y1e1d 5ynthe5e5 0f 0r9an0meta111c rare earth c0m- p0und5 7he 5u1ta6111ty 0f 60th 5ynthet1c and cata1y5t precur50r5 can 6e jud9ed 6y the c0n51derat10n 0f therm0dynam1c and k1net1c fact0r5 F0r examp1e, the kn0w1ed9e 0f meta1-119and 60nd 5tren9th5 can a5515t 1n a 6etter ana1y515 0f the therm0dynam1c5 0f archetyp1ca1119and exchan9e react10n5 and t0 e1a60rate the mechan15t1c 5cenar105 0f cata1yt1c tran5f0rmat10n5 [40]

Pr1nc1p1e51n 0r9an01anthan1de Chem15try

3.1

7herm0dynam1c and K1net1c 6u1de11ne5

Mark5 and c0-w0rker5 pr0v1ded a m05t va1ua61e exam1nat10n 0f a6501ute 60nd d15rupt10n entha1p1e5 0f var10u5 re1evant meta10r9an1c 119and5 X 1n Cp*25m-X 7he data were 06ta1ned 6y an10n1c t1trat10n ca10r1metry 1n t01uene (F19 4) [41] A1th0u9h the Ln-X 60nd5 5eem t0 6e therm0dynam1ca11y very 5ta61e, they u5u- a11y d15p1ay k1net1c 1a6111ty due t0 h19h 119and exchan9e a6111ty, che1at1n9 and 501- u6111ty effect5

5cheme 2 enc0mpa55e5 1mp0rtant 5ynthet1c 6u11d1n9 610ck5 and preferred 5ynthet1c 5trate91e5 1n 0r9an01anthan1de chem15try A5 ac1d/6a5e-type exchan9e react10n5 are fundamenta1, the 119and5 are dep1cted acc0rd1n9 t0 the1r 1ncrea51n9

pK a va1ue5 (1n water) 7h15 a150 c0rre1ate5 w1th the tendency t0 hydr01y2e (0r9a- n0meta111c5) 0r w1th the c0mpet1t10n 6etween 501vat10n and c0mp1exat10n 0n the 6a515 0f the H5A8 c0ncept (1n0r9an1c5)

7he centra1 p01nt 1n th15 c0n51derat10n 15 the L n - 0 H m01ety, the preferred f0rmat10n 0f wh1ch 15 ca11ed a d11emma 1n 0r9an01anthan1de chem15try 0r9a- n01anthan1de and p5eud0-0r9an01anthan1de c0mp0und5 read11y hydr01y2e when exp05ed t0 a1r and m015ture, w1th the f0rmat10n 0f hydr0x1de and 0x0- centered 119and c1u5ter 1ntermed1ate5 Lanthan1de c0mp1exe5 w1th Ln-C 11nka9- e5 are c0n51dered a5 0ver5en51t1ve c0mp0und5 [42] Even 119and5 w1th 10wer

pK a va1ue5 than water, a5 exemp11f1ed 6y 5u65t1tuted phen01119and5, tend t0 hy- dr01y2e 1n 0r9an1c 501vent5 6ecau5e the 1n501u61e hydr0x1de5 f0rmed act a5 a dr1v1n9 f0rce H0wever, the pre5ence 0f hard d0n0r funct10na11t1e5 0r mu1t1p1y char9ed an10n5 wh1ch are capa61e 0f che1at10n, can aff0rd m015ture-5ta61e a1k0x- 1de and am1de c0mp1exe5, a5 ha5 6een 5h0wn f0r 81N0L [43], p01ypyra201y160- rate [44] and p0rphyr1n-11ke c0mp1exe5 [45] Neverthe1e55, a11 0f the 0r9an01an- than1de c0mp1exe5 5h0u1d r0ut1ne1y 6e hand1ed under an 1nert 9a5 atm05phere 6y app11cat10n 0f h19h vacuum and 910ve-60x techn14ue5 [46]

~ 1n0r9an1c5

Ln-N03 Ln-Ha1

Ln-07f

k pKa (HL / H20)

Ln-H

5cheme 2 5ynthet1c 5trate91e5 t0ward5 0r9an01anthan1de c0mp0und5 [A: am1ne e11m1na- t10n react10n5, e.9 511y1am1de r0ute; 8: a1ky1at10n v1a a1k0x1de precur50r, e.9 ary10x1de r0ute; e: a1ky1at10n v1a am1de precur50r; D: hydr09en01y515 0f a1ky1 m01et1e5]

3.2

1n0r9an1c Rea9ent5

Lanthan1de ha11de5, n1trate5 and tr1f1ate5 are n0t 0n1y c0mm0n rea9ent5 1n 0r- 9an1c 5ynthe515 (F19 1) 6ut a150 repre5ent, 1n dehydrated f0rm, key precur50r c0mp0und5 f0r the m0re react1ve 0r9an0meta111c5 (5cheme 2) A5 a ru1e,1n c0m- p0und5 0f 5tr0n9 m0n06a51c ac1d5 0r even 5uperac1d5, cat10n 501vat10n c0mpete5 w1th an10n c0mp1exat10n, wh1ch 15 revea1ed 6y fu11y 0r part1a11y 5eparated an10n5 and 501vated cat10n5 1n the1r 5011d 5tate 5tructure5.7he tendency t0 f0rm 0uter 5phere c0mp1exat10n 1n c00rd1nat1n9 501vent5 [47] 15 u5ed a5 a cr1ter10n 0f the react1v1ty 0f 1n0r9an1c 5a1t precur50r5 1n 0r9an0meta111c tran5f0rmat10n5 Ln-Ha11de5

Anhydr0u5 1anthan1de ha11de5 are 10n1c 5u65tance5 w1th h19h me1t1n9 p01nt5 wh1ch take up water 1mmed1ate1y when exp05ed t0 a1r t0 f0rm hydrate5 (1 >8r

>C1 ) [48] 5tra19htf0rward 5ynthet1c acce55 and a fav0ra61e c0mp1exat10n/501va- t10n 6ehav10r make the 1anthan1de ha11de5 the m05t c0mm0n precur50r51n 0r9a- n01anthan1de chem15try Many 1mp0rtant Ln-X 60nd5 (X=C, 51, 6e, 5n, N, P, A5,

56, 81, 0, 5, 5e, 7e) can 6e 9enerated v1a 51mp1e 5a1t metathe515 react10n5 [4,8] 7he 50-ca11ed amm0n1um ch10r1de r0ute e1ther 5tart1n9 fr0m the 1anthan1de 0x1de5 0r

Pr1nc1p1e51n 0r9an01anthanJde Chem15try 11

5cheme 3 La60rat0ry pr0cedure5 f0r the preparat10n 0f 1anthan1de ch10r1de precur50r5

the hydrated ha11de5 15 the m05t p0pu1ar 1a60rat0ry pr0cedure (up5ca11n915 p05- 5161e) t0 anhydr0u51anthan1de(111) ch10r1de5 (5cheme 3) [49] 51mp1e therma1 de- hydrat10n wh1ch w0rk5 we11 f0r 1anthan1de tr1f1ate5 1ead5 t0 the f0rmat10n 0f un- de51red 1anthan1de 0xych10r1de5 Evan5 and c0-w0rker5 have 5h0wn that the 5tandard rec1pe f0r dehydrat1n9 CeC13(H20) 7 t0 make CeC13/RL1 w111 pr0duce [CeC13(H20)] n [50] CeC131RL1 15 a p0pu1ar 6r19nard-type rea9ent 1n 0r9an1c 5ynthe515 [51 ] wh1ch, f0r examp1e, 1ncrea51n91y t01erate5 funct10na19r0up5

A c00rd1nat1n9 501vent 5uch a5 tetrahydr0furan (7HF) 15 0ften nece55ary t0 react the 0therw15e 1n501u61e 1anthan1de ha11de5 v1a 5a1t metathe515.7he5e reac- t10n5 pr0ceed v1a 1n1t1a1 f0rmat10n 0f the m0re 501u61e c0mp0und5 LnX3(thf) x, wh1ch are 06ta1ned v1a 50xh1et extract10n and are p0pu1ar, we11-def1ned 5tart1n9 rea9ent5 [52] 7he extent 0f 7HF c00rd1nat10n depend5 0n 60th the 5tructura1 type 0f the anhydr0u5 1anthan1de ha11de and the preva111n9 cry5ta1112at10n c0n- d1t10n5, and affect5 1t5 501u6111ty and hence 1t5 react1v1ty [53] 5cC13(thf)3 15 6e5t 5ynthe512ed 6y an a1ternat1ve pr0cedure ut11121n9 50C12 a5 a dehydrat1n9 a9ent [54] Neutra1 d0n0r 119and5 5uch a5 capr01act0ne [53a], 2,6-d1methy1-4-py- r0ne [55] 0r che1at1n9 119and5 5uch a5 DME [56] and cr0wn ether5 [57,58] a150 revea1 unf0re5een and 1ntr19u1n9 c00rd1nat10n chem15try

0ther 5ma11-5ca1e 1a60rat0ry pr0cedure5 have 6een deve10ped f0r the d1rect 5ynthe515 0f the m0re react1ve 7HF adduct5, av01d1n9 1nc0nven1ent h19h tem- perature treatment [59-62] F0r examp1e, the preparat10n 0f LnC13(thf)x fr0m meta1 p0wder and hexach10r0ethane 15 fac111tated 6y 50n1cat10n [E4 (1)] [59] Add1t10na1 meta1-6a5ed 5ynthet1c r0ute5 1nc1ude the red0x tran5meta11at10n w1th mercury(11) ha11de5 [E4 (2)] [60] and the react10n w1th tr1methy1511y1 ch10- r1de and anhydr0u5 methan01 [E4 (3)] [61] Amm0n1a ha5 6een emp10yed a5 an a1ternat1ve d0nat1n9 501vent 1n the 5ynthe515 0f 1anthan1de a1k0x1de5 5tart1n9 fr0m 1anthan1de ch10r1de5 [63]

7HF

)))

+ 1CH2CH21, 7HF

- 0H20H 2 + 1.5 H912, 7HF

a 7HF 501ut10n and 1n 5011d f0rm [27] 1t5 7HF 501vate wa5 5ynthe512ed acc0rd1n9 t0 E4 (4) and wa5 5tructura11y character12ed a5 a 7-c00rd1nate 5m12(thf) 5 [70] 7he 1e55 501u61e Y612(thf) 2 can 6e 06ta1ned ana1090u51y [27] and the amm0n1a c0mp1ex 15 read11y f0rmed acc0rd1n9 t0 E4 (5) [69] 7m12(dme)3 15 the 0n1y 501- u61e 7m(11) c0mp0und 5ynthe512ed 50 far [E4 (6)] [71] A 1ar9e-5ca1e 5ynthe515 0f 5m8r 2 av01d1n9 the expen51ve meta1 precur50r ha5 6een acc0mp115hed acc0rd- 1n9 t0 the react10n 5e4uence 5h0wn 1n E4 (7) [68]

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 13

(7) L1, 7HF

5m8r3 ~ 5m8r2(thf)x

7he c0mp1ex (pyH)2(CeC16) ha5 6een d15cu55ed a5 an a1ternat1ve Ce(1V) pre- cur50r [72] P5eud0ha11de5 5uch a5 th10cyanate5 5h0u1d rece1ve 50me attent10n a5 5pec1f1c 5ynthet1c precur50r5 due t0 the1r dua1119at10n m0de [73] L1ke the ha1- 1de5 [74], the1r Ln(111) der1vat1ve5 have 6een 5ucce55fu11y emp10yed a5 cata1y5t5 1n 0r9an1c tran5f0rmat10n5 [75]

0 t h e r 1n0r9an1c 5a1t5

A1ternat1ve 1n0r9an1c precur50r5 wh1ch are referred t0 1n 5cheme 2 are a150 ava11a61e 6y treatment 0f 1anthan1de 0x1de5 Ln203 w1th the c0rre5p0nd1n9 ac1d [76,77] N1trate 119and5 c00rd1nate 5119ht1y 5tr0n9er t0 the 1anthan1de center5 c0mpared t0 ha11de5, 6ut are rep0rted t0 y1e1d c0ar5e prec1p1tate5 0f a1ka11 n1- trate5 1n 5a1t metathe515 react10n5 [78] N1trate5 are a150 preferred a5 precur50r5 1n macr0cyc11c chem15try where they preferent1a11y 0ccupy the 0uter 119at10n 5phere [7] 5tr0n9 c0mp1exat10n 0f d0u61y char9ed an10n5 (C032 >5042 ) CaU5e5

a C0n51dera61e decrea5e 1n 501U6111ty 0f the C0rre5p0nd1n9 Ln2X 3 and hence pre- c1ude5 the1r 6r0ad u5e a5 5ynthet1c precur50r5 [77] Ln-f1u0r1de5 [79] and ph05- phate5 are t0ta11y 1n501u61e 1n 501vent5 5u1ta61e f0r 0r9an0meta111c5 [4,15] P5eu- d0-1n0r9an1c 5a1t5 der1ved fr0m 5uperac1d5,1n part1cu1ar der1vat1ve5 0f tr1f1ate, c0nta1n weak1y c00rd1nat1n9 an10n5 and were 0ften f0und t0 6e 5uper10r t0 1an- than1de ha11de5 1n 5a1t metathe515 react10n5 [80] Anhydr0u5 Ln(07f) 3 can 6e ea511y 06ta1ned 6y therma1 dehydrat10n [E4 (8)] [81] Lanthan1de tr1f1ate5 have attracted c0n51dera61e attent10n a5 reu5ea61e Lew15 ac1d1c cata1y5t5 1n numer0u5 car60n-car60n 60nd-f0rm1n9 react10n5 [82]

7HF, - 3 NaC1 NdC13 + 3.3Na8H4 60 °C, 48 h > Nd(8H4)3(thf)2 (9)

CH3CN

Eu + 3 N08F4 ~ [Eu(0H30N)3(8F4)3]x + 3 N0 (10)

rt, 1d Cer1um amm0n1um n1trate [(NH4)2Ce(N03)6, CAN], a key 0x1d121n9 a9ent,15 the m05t c0mm0n Ce(1V) precur50r [86] 7he u5e 0f acety1acet0nate5 0f cer1ttm(1V) ha5 6een d15cu55ed [87] and Ce(07f) 4 5h0u1d a150 pr0ve t0 6e a va1ua61e precur50r [88]

Meta15

Lanthan1de meta15 wh1ch are c0nven1ent1y prepared fr0m the meta1 ha11de5 are c0mmerc1a11y ava11a61e 1n the f0rm 0f 1n90t5, ch1p5 (f111n95), f0115 and p0wder5 and are a150 hand1ed a5 pr0m1nent 5ynthet1c precur50r5 F0r examp1e, a1k0x1de c0m- p1exe5 der1ved fr0m cheap and 10w 60111n9 a1c0h015 are a1ternat1ve1y 5ynthe512ed fr0m meta15 under H9C12 cata1y515 [89] Repre5entat1ve examp1e5 f0r tran5meta1- 1at10n and tran5meta11at10n/119and exchan9e react10n5 are 91ven 1n E45 (11 )-(13) [90] Amm0n1a 501ut10n5 0f ytter61um and eur0p1um react w1th a var1ety 0f 8r0n- 5ted ac1d1c rea9ent5 acc0rd1n9 t0 E4 (14) [91] Meta10x1dat10n/119and tran5fer 0c- cur5 1n 7HF 1n the pre5ence 0f cata1yt1c [E4 (15)] and 5t01ch10metr1c am0unt5 0f 10d1ne [E4 (16)] [92]."Lanthan1de 6r19nard rea9ent5, f0rmu1ated a5 "RLn1 are prepared 1n 51tu fr0m the meta1 and the a1ky1(ary1)ha11de 1n 7HF [E4 (17)] [93] Ut1112at10n 0f an extreme1y 6u1ky a1ky1 119and a110wed the 1501at10n 0f {Y6[C(51Me3)3]1(0Et2)} 2 acc0rd1n9 t0 a 5a1t metathe515 react10n [94]

80 °C, 20h

7HF 5m + H9(C6F5) 2 + 2HNR 2 12h ~ 5m(NR2)2(thf)4 +

7HF Y6 + 5n[N(51Me3)212 ~ Y6[N(51Me3)212(thf)2 + 8n (13)

80 °C, 8h

- H2, -NH 3 12(0, 7HF, Py

50 °C, 48 h

L.a12(thf)2 7HF

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 15

1.7HF, -3 KC1, 20 °C LnC13 + 3 K[N(51Me3)2] J, Ln[N(51Me3)213 (18)

2 5u611mat10n pure 1.7HF, -3 KC1, 70 °C

pure

0Ar = 006H318u2-2,6; 006H2t8u2-2,6-Me-4

7he 511y1am1de R0ute

Rare earth 511y1am1de c0mp1exe5 have n0t 0n1y attracted en0rm0u5 attent10n f0r the 5ynthe515 0f precata1y5t 5y5tem5 6ut a150 f0r the 1501at10n 0f we11-def1ned

ed 1n numer0u5119and exchan9e react10n5 w1th 5u65trate m01ecu1e5 0f 1ncrea5ed 8r0n5ted ac1d1ty 5uch a5 a1c0h015, phen015, cyc10pentad1eny15, acety1ene5, ph05- phane5, and th1015 a5 115ted 1n 5cheme 5 [ 103-113]

Fact0r5 wh1ch 0ften make the 511y1am1de r0ute 5uper10r t0 trad1t10na15a1t me- tathe515 react10n5 are (1) the react10n 1n n0n-c00rd1nat1n9 501vent5 due t0 the h19h 501u6111ty 0f the m0n0mer1c meta1 am1de5, (11) m11d react10n c0nd1t10n5 0f- ten at am61ent temperature, (111) av01dance 0f ha11de c0ntam1nat10n, (1v) ea5e 0f pr0duct pur1f1cat10n [rem0va1 0f the re1ea5ed am1ne a10n9 w1th the 501vent un- der vacuum (6p HN(51Me3)2:125 C)], (v) 6a5e-free pr0duct5 (c00rd1nat10n 0f the 5ter1ca11y demand1n9, re1ea5ed am1ne 15 d15fav0red), (v1) 4uant1tat1ve y1e1d , and (v11) the fac11e ava11a6111ty 0f m0n0- and heter061meta111c am1de precur50r5

A 11m1t1n9 fact0r 0f th15 5pec1f1c am1ne e11m1nat10n r0ute 15 the 5ter1c 6u1k 0f the [N(51Me3)2] 119and, 06v10u51n 1nc0mp1ete exchan9e react10n5 w1th 51m11ar1y 6u1ky 119and5 5uch a5 Cp*H [104], H0Ct8u 3 [114] 0r h19h1y 5u65t1tuted ph05- phane5 [108] 1n 0rder t0 6etter c0pe w1th 5uch 5ter1ca11y 5uppre55ed 119and ex- chan9e react10n5 the a1ternat1ve 511y1am1de precur50r Ln[N(51HMe2)213(thf) 2, wh1ch can 6e prepared 1n h19h y1e1d f0r a11 0f the 1anthan1de e1ement5 [yttr1um: E4 (20)] [115], ha5 6een 1ntr0duced

n-hexane, - L1C1 YC13(thf)3.5 + 2.9 L1N(51HMe2)2 ~ Y[N(51HMe2)213(thf)2 (20)

1t, 16h

7he 615(d1methy1511y1am1de) 119and [N(51HMe2)2] n0t 0n1y fav0r5 the attack 0f pr0t1c rea9ent5 6y decrea5ed 5ter1c 6u1k,6ut am1ne e11m1nat10n 15 a150 affected 6y a decrea5ed 511y1am1de 6a51c1ty, ea51er w0rkup pr0cedure5 (6p HN(51HMe2)2: 93-99 C) and the pre5ence 0f an exce11ent 5pectr05c0p1c pr06e (51-H) Ac- c0rd1n9 t0 th15 extended 511y1am1de r0ute , cata1yt1ca11y re1evant c0mp1exe5 w1th 5a1en [ 116], (5u65t1tuted) 11nked-1ndeny1 [ 117], and 5u1f0nam1de 119and5 [ 118] have 6een 5ynthe512ed (F19 6) 5uch c0ntr011ed 119and a550c1at10n5, wh1ch are

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 17

t8u 1Pr • ~0

1p r/L ~/ ~1Pr F19 6 C2-5ymmetr1c rare earth c0mp1exe5 acc0rd1n9 t0 the extended 511y1am1de r0ute

5c013(thf)3 + 3 L1CH251Me3, n-hexane,-3 L1C1 0°C, 1h 8c(CH281Me3)3(thf)2 ]- 251Me4 ~ + H2L, Me251• 5C NMe2

J rt, 30m1n ~ •N / ~0H28JM03

1

t8u

5cheme 6.1n 51tu 9enerat10n 0f a react1ve a1ky1 precur50r

pr0p05ed a5 pr0ceed1n9 v1a 7HF d1550c1at10n, are n0t 06ta1ned w1th the Ln[N(51Me3)2] 3 5y5tem

7he app11cat10n 0f the m0re 6a51c Ln(N1Pr2)3(thf ) a5 a meta10r9an1c precur- 50r c0mp0und 15 c0ntr0ver51a1 [119] 6ecau5e 1t5 ava11a6111ty 15 hampered 6y ate c0mp1exat10n [5ect 5.1, L1Ln(N1Pr2)4] and enhanced therma1 1n5ta6111ty (de- c0mp051t10n at 100 C/10 4 70rr) [120] An eff1c1ent a1kane e11m1nat10n react10n ut11121n9 the 1n 51tu f0rmed a1ky1 5pec1e5 Ln(CH251Me3)(thf)2 pr0duced c0m- p1exe5 w1th 11nked am1d0 cyc10pentad1eny1 119and5 (5cheme 6) [121] H0wever, the therma11n5ta6111ty 0f Ln(CH251Me3)(thf)2 and ate c0mp1ex f0rmat10n 5eem t0 6e 11m1t1n9 fact0r5 [122]

7he 511y1am1de r0ute can a150 6e app11ed t0 1anthan1de(11) chem15try

(5cheme 7) A1th0u9h the we11-character12ed c0mp1exe5 Ln[N(51Me3)212(thf)2 exh161t enhanced 5ter1c f1ex16111ty [123], the 5c0pe 0f exchan9e react10n5 15 n0w 11m1ted 6y the reduct1ve pr0pert1e5 0f 5m(11) F0r examp1e, 5m(11) am1de5 tend t0 9et 0x1d12ed 6y en0112a61e a1c0h015 [124] H0wever, ary10x1de5 0f type 5m(0Ar)2(thf)x have 6een 1501ated and ate c0mp1exat10n a5 ev1denced 1n [K5m(0C6H3-2,6-t8u2)3(thf)] n pr0ve5 t0 6e a 5ta611121n9 fact0r [125].Acc0rd1n9 t0 th15 1atter appr0ach, m1xed meta111c c0mp1exe5 can 6e 06ta1ned 6y retent10n 0f the 0r191na1 meta1119and c0mp051t10n Part1a11y exchan9ed heter01ept1c c0m- p1exe5 5uch a5 {K5mCp*2[N(51Me3)2] (thf)2}n are ava11a61e due t0 5ter1c re5tr1c- t10n5 [126] Eu(11) and Y6(11) 511y1am1de5 are acce55161e t0 a11 0f the exchan9e re- act10n5 115ted 1n 5cheme 5 [127]

{K8m[N(81Me3)213}n

+ 3n H0Ar, n-5exane

- 3n HN(51Me3)2 [K5 m(0C6H2t8U2-2,6- Me-4)3]n

F / • (thf)2 / • (thf)24

1•

t01uene/7HF 2n H N (51Me3)2~-

- H0p*

5cheme 7 Heter061meta111c 8m(11) c0mp1exe5 acc0rd1n9 t0 the 511y1am1de r0ute

0r9an0meta111c der1vat1ve5 0f eur0p1um and ytter61um are a150 read11y f0rmed v1a react10n51n 114u1d amm0n1a 7he act1ve 5pec1e51n the5e react10n5 are the hexaamm1ne c0mp1exe5 and the 0n1y 6ypr0duct5 are hydr09en and amm0- n1a [E4 (21a-c)] Acc0rd1n9 t0 th15 pr0cedure, the c0mp0und5 EuCp2 [128],Y6- Cp*2(NH3) x [91], Ln(C07) (Ln=Eu,Y6) [129, 130], Eu(C -CMe)2 [131], Eu(Ph2) 2 [132], Y6(0C6H2t8u2-2,6-Me-4)2(thf) 3 [90c], LnX 2 (Ln=Eu, Y6; X=C1, 8r, 1) [133] and deca60rate5, e.9 (NH3)xY6(810H14) [134] have 6een 5ynthe512ed

6enerat10n 0f Lanthan1de A1ky1 80nd5

Lanthan1de a1ky1 c0mp0und5 are 1mp0rtant a1ky1 tran5fer rea9ent5 and 1n1t1ate

a var1ety 0f cata1yt1c react10n5.7he tran5f0rmat10n 0f 1anthan1de a1k0x1de 60nd5 t0 1anthan1de a1ky160nd5 5eem5 t0 6e an attract1ve a1ternat1ve t0 the a1ky1at10n 0f 1anthan1de ha11de5 w1th a1ka11 meta1 a1ky1 c0mp0und5 F0r examp1e, the ary- 10x1de r0ute aff0rd5 h0m01ept1c 1anthan1de a1ky15 1n 900d y1e1d [E4 (22)] [135]

n-hexane, - 3 L10Ar Ln(0C6H2t8u2-2,6)3 + 3 L1CH(51Me3)2 rt, 30m1n ~" Ln[CH(51Me3)213 (22)

Due t0 the h19h 501u6111ty 0f the 5tart1n9 and the re5u1t1n9 rare earth c0mp1ex- e5, the react10n can 6e c0nducted 1n n0np01ar 501vent5 fr0m wh1ch the 1n501u61e a1ka11 ary10x1de5 can ea511y 6e 5eparated H0wever, th15 type 0f k1net1ca11y c0n- tr011ed metathe515 react10n 15 very 5en51t1ve t0ward5 the react10n c0nd1t10n5 1n- c1ud1n9 the type 0f a1k0x1de (ary10x1de) 119and, type 0f meta1, num6er and type 0f c0-119and5, 5ta6111ty and 501u6111ty 0f the e11m1nated a1ka11 meta1 a1k0x1de (ary10x1de), 501vent, temperature, etc A5 a re5u1t, 1nc0mp1ete 119and exchan9e, exchan9e 0f the c0-119and, ate c0mp1exat10n, exchan9e e4u1116r1a and 119and re-

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 19

d15tr16ut10n can 0ccur 5cheme 8 91ve5 an 1dea 0f the c0mp1ex1ty 0f the5e a1k0x- 1de-der1ved a1ky1at10n react10n5 [136-139] Acety1acet0nate c0mp1exe5 have 6een d15cu55ed a5 a1ternat1ve a1ky1 precur50r5 [87]

A1um1num a1ky15,1n part1cu1ar tr1methy1a1um1num, pr0duce che1at1n9 a1ky1 a1k0x1de m01et1e5, [(9-0t8u)A1Me2(9-Me)], v1a Lew15 ac1d/6a5e-pa1r f0rmat10n [ 140,141 ] 1n the react10n w1th Y3(0t8u)7C12(thf)2, A1Me 3 51mu1tane0u51y act5 a5

a p0werfu1 denuc1eat10n rea9ent t01erat1n9 etherea1501vent5 5uch a5 7HF at the 1anthan1de center (5cheme 9) React10n pr0duct5 5uch a5 LnC13(dme) 2 ar15e fr0m 119and red15tr16ut10n5 (5ect 5.3) 7he h0m01ept1c c0mp1ex Ln[(9-0t8u)A1Me 2

hexane Cp*Ce(0Ar)2 + eXC KCH(51Me3)2 ~

- K(0Ar) Cp*Ce(0Ar)[CH(51Me3)2] +

appr0x 10 % Cp*Ce(0Ar)2 hexane

Cp*Y(0Ar)2 + 2 MCH(51Me3)2 ~ Cp*Y(0Ar)[CH(51Me3)2] + M(0Ar)

Lt C)~u 0 ~ = 0C2H40Me 5t Me2 5tructura11y character12ed pr0duct5

5cheme 8 React10n 6ehav10r 0f 1anthan1de ary10x1de and a1k0x1de c0mp1exe5 t0ward5 a1ka11 meta1 a1ky1 rea9ent5 (0Ar=C6H3t8u2-2,6)

5cheme 10 A1ky1at10n 0f 1anthan1de am1de c0mp1exe5 w1th 9r0up 13 meta1 a1ky15 (M=A1, 6a)

(p-Me)] 3 can 6e 06ta1ned a5 the 501e pr0duct fr0m the react10n 0f A1Me 3 w1th Ln3(0t8u) 9 [142]

Extended a1ky1at10n 15 065erved when 1anthan1de am1de c0mp1exe5 are u5ed a5 5ynthet1c precur50r5 [107,143] 7he f0rmat10n 0f a 5tr0n9 9r0up 13 meta1- N(am1de) 60nd pr0m0te5 th15 type 0f a1ky1at10n react10n Depend1n9 0n the 5t0- 1ch10metry, the react10n 0f MMe 3 (M=A1, 6a) w1th Ln(NMe2)3(L1C1) 3 y1e1d5 part1a11y 0r pera1ky1ated 5pec1e5 (5cheme 10) A9a1n, the react1v1ty 15 determ1ned 6y 5ter1c fact0r5 F0r examp1e, the 5ter1ca11y encum6ered La[N(51Me3)2] 3 d0e5 n0t 5h0w any tendency t0 f0rm a Lew15 ac1d/6a5e adduct w1th 9r0up 13 meta1 a1ky15, a prere4u151te f0r 5u65e4uent a1ky1at10n under the5e

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 21

c0nd1t10n5 [115] H0wever, pera1ky1ated pr0duct5 are 06ta1ned fr0m Ln[N(51HMe2)2] 3(thf) 2, 5m[N(51Me3)2] 2(thf) 2, and K5m[N(51Me3)2] 3 [8,115] 6enerat10n 0f Lanthan1de Hydr1de 8 0nd5

0r9an01anthan1de hydr1de c0mp1exe5 are a150 key rea9ent5 1n rare earth cata1y- 515.7he h19h1y react1ve 1anthan1de hydr1de 60nd5 n0t 0n1y 5erve a5 cata1yt1c 1n- 1t1at0r5 6ut are a150 0ften a55umed key 1ntermed1ate5 1n cata1yt1c react10n5 5uch a5 the hydr0511y1at10n [144] and 01ef1n p01ymer12at10n react10n (~-H e11m1na- t10n) [145] 7he hydr09en01y515 0f a1ky1 c0mp1exe5 15 a fav0ra61e r0ute f0r 5yn- the5121n9 1anthan1de hydr1de 60nd5 [E4 (23)] [146] H0wever, 5ma11 chan9e5 1n the 512e 0f the meta1, the 512e 0f the a1ky19r0up, 501vent, de9ree 0f a550c1at10n 0f the c0mp1ex, 0r type 0f c0-119and cau5e 5u65tant1a1 chan9e5 1n react1v1ty [137,146]

n-hexane 0p2Ln0H(51Me3) 2 + H 2 (1 atm) 0 °0, 3h = [0p2Ln(1~-H)] 2 + H20(51Me3) 2 (23)

A1th0u9h 5011d 5tate 5tructure5 0f the5e c0mp1exe5 exc1u51ve1y d15p1ay 6r1d9- 1n9 ~Ln(9-H)nLn~ m01et1e5 [4], a f1ux10na1 6ehav10r 1n 501ut10n w1th term1na1 Ln-H 60nd5 a5 the react1ve 5pec1e5 ha5 6een 5u99e5ted [147] L1A1H 4 act5 a5 an e1e9ant hydr1de tran5fer rea9ent and depend1n9 0n the nature 0f the meta1 and d0n0r 119and, a5 we11 a5 the cyc10pentad1eny15u65t1tut10n, d1nuc1ear 5pec1e5 are f0rmed (5cheme 11) [148] 51m11ar un501vated d1nuc1ear 5pec1e5 were 06ta1ned fr0m the reduct10n 0f a1ane 6y 5m(11) 0r9an0meta111c5 [E4 (24)] [149] Lantha- n1de hydr1de 5pec1e5 can a150 6e 9enerated 6y therma1 treatment 0f 1anthan1de a1ky1 c0mp1exe5 5uch a5 Cp2Lnt8u [150] 0r 6y 5a1t metathe515 react10n5 emp10y- 1n9 NaH [151] 7he therma1 dec0mp051t10n 0f the 5ter1ca11y cr0wded 1anthan1de a1k0x1de c0mp1ex Ln(0Ct8u3) 3 pr0duced a 6r1d9ed hydr1de 5pec1e5 a5 a 51de pr0duct (5cheme 12) [109]

[(C5H4t8u2-1,3)25mC112 + 2 L1A1H4 ~[(C5H4t8u2-1,3)25mA1H412(tmeda)

+ 7MEDA, - A1H3(tmeda ) [(C5H4t8U2-1,3)25m]2H[A1H4(tmeda)] > [(C5H4t8U2-1,3)25m(F-H)] 2

5cheme 11.6enerat10n 0f 1anthan1de hydr1de 60nd5 v1a a 5a1t metathe515 react10n

90%

0.5 [Ce(0CHt8u2)312 + 3 1-C4H8 Ce(0Ct8u3)3

150 °C, vacuum 10%

(1/n) [Ce(0CHt8u2)2H]n + 31-C4H8 + t8u2C0

5cheme 12.6enerat10n 0f 1anthan1de hydr1de 60nd5 v1a therma1 de9radat10n

Generation of Cationic Organolanthanide Species

Several routes are currently applied to synthesize cationic organolanthanidespecies, including the halide abstraction from heteroleptic Ln(III) compounds[Eq (25)] [152], the oxidation of divalent metallocenes [Eqs (26) and (27)][153], the protolysis of lanthanide alkyl and amide moieties [Eqs (28) and (29)][154,155], and anion exchange [Eqs (30) and (31)] [84,156] In the absence of acoordinating solvent such extremely electrophilic species attain stabilization viaarene interactions with the BPh4– anion (Sect 5.1) [153b] Cationic rare earthspecies have been considered as promising candidates for Lewis acid catalysis[157]

Pr1nc1p1e51n 0r9an01anthanJde Chem15try 23

3.4

7herma15ta6111ty

De5p1te the k1net1c 1a6111ty 0f the Ln-X c~-60nd5 (even the therm0dynam1ca11y very 5ta61e Ln-0R 60nd under90e5 rap1d 119and exchan9e react10n5 [158]), 0r- 9an01anthan1de c0mp0und5 are therma11y r06u5t 0ver a w1de ran9e 0f tempera- ture [99,100,102,104,159-165] 7herma1 5ta6111ty 15 1mp0rtant f0r c0nduct1n9 119and exchan9e react10n5 and cata1yt1c tran5f0rmat10n5 at e1evated tempera- ture5 [1,22] 7he 5u611mat10n 6ehav10r 15 a cr1ter10n 0f therma1 5ta6111ty, and 15 fre4uent1y c0n5u1ted t0 jud9e the 5u1ta6111ty 0f v01at11e m01ecu1ar precur50r5 f0r chem1ca1 vap0r dep051t10n techn14ue5 (F19 7)

8u1ky 119and5 affect the 10n1c nature 0f the p01ar12ed Ln-X 60nd 6y m1n1m12- 1n9 p01ar 1nteract10n5 (1ntra- and 1nterm01ecu1ar) and 0pt1m121n9 v01at111ty 6y the c0ncept 0f 5ter1c 5h1e1d1n9 7he detect10n 0f 1501ated m01ecu1e5 1n5tead 0f 5a1t-11ke arran9ement5 1n the 5011d 5tate c0nf1rm5 th15 trend 7he p01ar121n9 ef- fect can a150 6e reduced 6y 1ntr0duct10n 0f d0n0r-funct10n112ed 119and5 wh1ch can 6r1n9 a60ut char9e tran5fer t0 the meta1 cat10n Dec0mp051t10n pathway5 can 6e 5ter1ca11y 610cked 6y f1111n9 the c00rd1nat10n 5phere 0f the meta1 w1th 1ar9e 119and5 H0wever, 5ter1ca11y 0vercr0wded 119and5 may de9radate at e1evat-

ed temperature a5 111u5trated f0r the Ln(0Ct8u3) 3 5y5tem [109]

4

LJ9and C0ncept5

L19and de519n 0ccup1e5 a p1v0ta1 r01e 1n 0r9an01anthan1de chem15try 7he nature 0f the 119and, 1nc1ud1n91t5 512e, 6a51c1ty, and funct10na112at10n, pr0mpt1y affect5 c0mp1ex feature5 5uch a5 (m0n0)nuc1ear1ty, cat10n 512e and e1ectr0ph111c1ty Pr0- 11f1c meta1 cat10n/119and 5yner915m5 1mpart n0ve1 react1v1ty pattern5 wh1ch can

F19 7.5u611mat10n 6ehav10r 0f var10u5 1anthan1de c0mp1exe5 at 10 5 m6ar (0EP 2,3,7,8,12,

13,17,18-0cta(ethy1)p0rphyr1n; acac acety1acet0nate)

e-h0m01ept1c d-h0m01ept1c ate-e-h0m01ept1c ate-d-h0m01ept1c

F19.8 M0de5 0f h0m01ept1c Ln(111) c00rd1nat10n (D0 d0n0r funct10na11ty)

6e 0f 1ntere5t 1n, f0r examp1e, 119and-enhanced 5tere05e1ect1ve cata1y515 [166] 7heref0re, 119and c1a551f1cat10n and adaptat10n de5erve part1cu1ar attent10n A55um1n9 the 119and 1nteract10n t0 6e 0f e1ectr05tat1c 0r191n, 0pt1ma1 char9e 6a1ance 0f the 1anthan1de(111) cat10n5 5h0u1d 6e ach1eved 6y three 5ta61e an10n1c 119and5.1dent1ca1 an10n5 acc0mp115h 50-ca11ed h0m01ept1c 5y5tem5 wh1ch can 6e 0f neutra1 type (MRn) x 0r ate type [MRn] 2 [Xm] 2+ [ 167] H0m01ept1c c0mp0und5 can 6e further c1a551f1ed a5 t0 whether the 119and5 are c00rd1nat1ve1y e4ua11y (e-

h0m01ept1c) 0r d1fferent1y (d-h0m01ept1c) attached t0 the meta1 center (F19 8) 7he d-h0m01ept1c m0de 15 f0und 1n 01190mer1c 5y5tem5 where 60th term1na1 and 6r1d91n9 119and5 are pre5ent; h0wever, they are a150 f0und 1n m0n0mer1c c0m- p1exe5 wh1ch c0nta1n funct10na112ed 119and5 Here, 5ter1c 0ver5aturat10n can pre- vent the f0rmat10n 0f e-h0m01ept1c c00rd1nat10n [31,168]

Heter01ept1c 0r9an01anthan1de c0mp1exe5 c0nta1n1n9 react1ve Ln-X 60nd5 and 5ta611121n9 anc111ary 119and5 are key precur50r c0mp0und51n cata1yt1c tran5- f0rmat10n5 M0n0nuc1ear1ty 15 u5ua11y a prere4u151te f0r 60th 900d 501u6111ty and react1v1ty Ut1112at10n 0f 6u1ky 119and5, ate c0mp1exat10n, and d0n0r func- t10na112at10n are app11ca61e pr0cedure5 f0r 9enerat1n9 m0n0nuc1ear c0mp1exe5

4.1

5ter1c 8u1k and D0n0r Funct10na112at10n

5cheme 13 empha512e5 the effect 0f 5ter1ca11y demand1n9 9r0up5 0n the 9enera- t10n 0f h0m01ept1c m0n0nuc1ear c0mp1exe5.7h15 m0d1f1cat10n 0ften 91ve5 ac- ce55 t0 c1a55e5 0f c0mp0und5 wh1ch are n0t 1501a61e/def1ned 1n the pre5ence 0f c0rre5p0nd1n91y 5ma11 119and5 Var10u5 examp1e5 feature 60th d1fferent Ln-X 60nd5 and d1fferent 0x1dat10n 5tate5 [169] 5tructura11y character12ed Ln-C 60nded h0m01ept1c 5y5tem5 1nc1ude a1ky1 [94,135], cyc10pentad1eny1 [31,170], pentad1eny1 [ 171], pentamethy1cyc10pentad1eny1 [ 172], 1ndeny1 [ 173], cyc100cta- tetraeny1 [80e], (a2a)a11y1 [ 174] and arene der1vat1ve5 [26] Repre5entat1ve exam- p1e5 0f p5eud0-0r9an0meta111c5 c0nta1n1n9 Ln-N 60nd5 c0mpr15e 511y1am1de, a2a6utad1ene,6en2am1d1nate and p0rphyr1n c0mp1exe5 [114,175-178].Ary10x1de, a1k0x1de, ~-d1ket0nate and 5ch1ff 6a5e 119and5 can 5ta61112e h0m01ept1c m0n0- nuc1ear Ln-0 der1ved c0mp1exe5 [101,179-182] Der1vat1ve5 featur1n9 ph05ph0- ru5 and 5u1fur 60nd5 1nc1ude a1ky1 ph05ph1de5 [183] and ary1 and a1ky15u1f1de5 [90c,184]

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 25 [015-05H5)25m (1~-~15:~12-0p)]~ , ~>

5cheme 13.7racta61e, m0n0nudear 5pec1e5 v1a

kn0wn/n0t 5ta61e; 6de9ree 0f a9910mer12at10n

5m[~15-05(0H3)513 Ln{CH[51(CH3)312}3 Y6{C[51(CH3)313}2 Ln{N[51(CH3)312}3 Ln{006H210(0 H3)312-2,6-0 H3-4}3 Ln{506H210(0 H3)312-2,4,6}3

5ter1c ca11y 6u1ky 119and5 (ac0mp0und n0t n0t determ1ned)

7he attachment 0f p0tent1a11y c00rd1nat1n9 9r0up5 pr0duce5 d0n0r-funct10n- a112ed 119and5 and 15 a p0pu1ar appr0ach t0 f1ne-tuned anc111ary 119and5.7h15 15 part1cu1ar1y appea11n9 1n 0r9an01anthan1de chem15try [185], c0n51der1n9 the 1ar9e 512e 0f the 1anthan1de cat10n5 and the1r preference f0r h19h c00rd1nat10n num6er5 1ntram01ecu1ar r1n9 f0rmat10n v1a dat1ve 60nd5 [186] acc0rd1n9 t0 the H5A8 c0ncept 5ta61112e5 m0n0nuc1ear c0mp1exe5 v1a the effect 0f che1at10n and entr0py L19and-60nded d0n0r 9r0up5 5ucce55fu11y c0mpete w1th d0nat1n9 501vent m01ecu1e5 f0r c00rd1nat10n 51te5, 1mp1y1n9 1mpr0ved therma1 6ehav10r 6y 5uppre551n9 01190mer12at10n dur1n9 heat1n9 and 5u611mat10n 7he pre5ence 0f 1ntram01ecu1ar1y act1ve d0n0r funct10na11t1e5 affect5 the p01ar1ty 0f the 1an- than1de-c0unter10n 60nd 6y m0re 0r 1e55 pu5h1n9 e1ectr0n den51ty 1nt0 the met- a1 A5 a re5u1t 5tr0n9 d0n0r 9r0up5 w111519n1f1cant1y decrea5e the react1v1ty 0f an adjacent, k1net1ca11y 1a611e Ln-X 60nd, 6ut 0n the 0ther hand enhance 1t5 5ta611- 1ty a9a1n5t hydr01y515 Hence, the 6a1ance 0f d0n0r 5tren9th 15 1mp0rtant f0r the pr0duct10n 0f a f1ex161e c00rd1nat10n m0de, revea1ed 6y arm 0n - arm 0ff pr0ce55e5.5uch hem11a611e 119and5 are pr0p05ed a5 d1rect1n9 the appr0ach 0f 0r- 9an1c 5u65trate5 1n cata1yt1c tran5f0rmat10n5 [187] 1n the a65ence 0f r1n9 5tra1n the 60nd 5tren9th 0f 5uch an 1ntram01ecu1ar c00rd1nat10n re5em61e5 that 0f the c0rre5p0nd1n9 1nterm01ecu1ar 0ne [188] F0r examp1e, the 5tren9th 0f an 1n- tram01ecu1ar hard * 0R2 c00rd1nat10n w1116e 1n the ran9e 0f 5-7 kca1/m01 a5 determ1ned f0r 1nterm01ecu1ar 7HF c00rd1nat10n [41]

F19ure 9 0ut11ne5 9enera15trate91e5 0f d0n0r funct10na112at10n app11ed 1n 1an- than1de a1ky1 [189-193], am1de [194-196] and a1k0x1de chem15try [180,197,198] Hard d0n0r funct10na11t1e5 5uch a5 NMe 2 and 0Me d0m1nate th15 5cenar10 and 1t 15 0ften the c0m61nat10n 0f 5ter1c 6u1k and d0n0r 119at10n wh1ch 1ead5 t0 the env15a9ed m0n0nuc1ear 5pec1e5 D0n0r funct10na112at10n 0f a1ky1119and5 pr0ved t0 6e 5ucce55fu1 even 1n 5ta611121n91anthan1de a1ky160nd51n a 10w-va1ent 5m(11) 5pec1e5 [ 191 ] A11y11c m01et1e5 are a150 very effect1ve 1n 5ta611121n910w a99re9ated 0r9an01anthan1de 5pec1e5 a5 ev1denced 1n m0n0nuc1ear h0m01ept1c ph05ph1-

F19.10 Funct10na112at10n 0f cyc10pentad1eny1119and5

n0methan1de [199],6en2am1d1nate [200] and a2aa11y1 c0mp1exe5 [177] Mu1t1p1e funct10na112at10n d15p1ay5 an0ther 0pt10n.A5 revea1ed 1n ary1 [193] and 511y1am1de der1vat1ve5 [195], d0n0r m01et1e5 f1ank the centra160nd1n9 un1t 1n a p0tent1a11y tr1dentate che1at1n9 array

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 27

N0t 5urpr151n91y, d0n0r funct10na112at10n ha5 6een exten51ve1y app11ed t0 ta1- 10r cyc10pentad1eny1119and5 (F19 10) 1n add1t10n t0 the attachment 0f 0ne pen- dant d0n0r arm [ 160,201], funct10na112at10n v1a d0n0r-11nked 615(cyc10pentad1- eny1) 119and5 [202], 1nc1ud1n9 d0n0r-tethered 5111c0n 6r1d9e5 [203], and d0n0r funct10na112ed ch1ra1 51de cha1n5 are f0und [204] 0n1y a few examp1e5 feature 50ft d0n0r funct10na11t1e5 5uch a5 ph05ph1ne5 [205] and arene5 [206]

4.2

Anc111ary L19and5

Var10u5 term51nc1ud1n9 5pectat0r 119and , aux111ary 119and 0r anc111ary 119and are u5ed t0 character12e the p0rt10n 0f the 119and 5phere wh1ch 15 n0t d1rect1y 1n- v01ved 1n 6a51c react1v1ty 5tep5 5uch a5 1n5ert10n 0r 119and exchan9e react10n5 Pr1mar11y, anc111ary 119and5 5erve t0 prevent 01190mer12at10n 0r p01ymer12at10n 0f e1ectr0n1ca11y and c00rd1nat1ve1y un5aturated der1vat1ve5, and t0 1mpart k1- net1c 5ta6111ty f0r 0therw15e h19h1y react1ve 5pec1e5.7he m0n0nuc1ear1ty, chem- 1ca1 r06u5tne55 and r191d1ty ant1c1pated are c0mm0n attr16ute5 0f a we11-def1ned precata1y5t 5y5tem Furtherm0re, anc111ary 119and5 can d1rect cata1yt1c pr0ce55e5 1f the1r 6u1k1ne55 cau5e5 meta15h1e1d1n9 and 5ter1c c0n5tra1nt5,1f d1fferent1y p0- 1ar12ed Ln-X 60nd5 affect the e1ectr0ph111c1ty 0f the meta1 center, 0r 1f they ex- h161t a re5erv01r f0r ch1ra11ty and add1t10na1 f1ex161e c00rd1nat10n 51te5

Hence, 5ynthet1c 0r9an01anthan1de chem15try put5 the ma1n empha515 0n the adapt10n 0f preva111n9 precata1y5t type5 t0 the re4u1rement5 0f h19h1y enant105e- 1ect1ve cata1y515.7h15 15 1mpre551ve1y dem0n5trated 6y t1ed-6ack cyc10pentad1- eny1 c0mp1exe5 [207], even water-5ta61e 81N0L 5y5tem5 [43], and f1u0r1nated ~- d1ket0nate c0mp1exe5 (F19 11) [208]

[Me251(C5Me4)(C5H3R*)]LnN (5JMe3)2 Na3La[(5)-81N0L)]3(thf)6(H20) Eu(hfc)3

F19.11 Deve10pment 0f 50ph15t1cated 119and env1r0nment5 f0r enant105e1ect1ve cata1y515

[ thd 2,2,6,6-tetramethy1- 3,5-heptaned10ne, hfc 3-(heptaf1u0r0pr0py1hydr0xymethy1ene)-d-

camph0rat0]

R R

/

N

R /

0

A ~

F19.12 Am1de and a1k0x1de m01et1e5 a5 cyd0pentad1eny1-ana1090u5119and5

Cyc10pentad1eny1 der1vat1ve5 and re1ated 5y5tem5 5uch a5 1ndeny1 and f1u0re- ny1 5t111 p1ay a d0m1nant r01e 1n 119and f1ne-tun1n9 H0wever, 119and de519n ha5 9radua11y reached a h19h 1eve1 0f var1ety and 50ph15t1cat10n, e.9 a5 pre5ented 6y the new 9enerat10n 0f 9r0up 4 meta1 n0n-meta110cene cata1y5t5 (f0r 01ef1n p0- 1ymer12at10n) [209,210] 1n part1cu1ar, che1at1n9 n1tr09en-c0nta1n1n9 c0unter 119and5 have 6ec0me the f0cu5 0f much attent10n [209] 51m11ar t0 the re1ated a1k0x1de 119and5 [210], they 0ffer a 10wer f0rma1 e1ectr0n c0unt, thu5 render1n9

a m0re e1ectr0ph111c and theref0re p0tent1a11y m0re act1ve cata1y5t fra9ment (F19 12) [37] Anc111ary 119and5, rep0rted f0r Ln(111) 5pec1e5, can 6e c1a551f1ed ac- c0rd1n9 t0 the1r char9e (va1ency) and c00rd1nat10n m0de (F19ure5 13-15)

M0n0va1ent L19and5

Numer0u5 m0n0-char9ed cyc10pentad1eny15u65t1tute5 have 6een d15cu55ed 1n re1- evance t0 the cata1y515 t0p1c 7he attachment 0f 0ne 0r tw0 0f 5uch 119and515 ea511y perf0med and may render tw0 0r 0ne react1ve 51te5, re5pect1ve1y 7he re5u1t1n9119- and 5phere 0ffer5 enhanced 5ter1c f1ex16111ty, and k1net1c 1nertne55 0f the m0n0va- 1ent anc111ary 119and 15 0ften ach1eved v1a che1at10n thr0u9h char9e de10ca112at10n 0r d0n0r funct10na112at10n 7he 5ta6111ty 0f the re5u1t1n9 c0mp1exe5, h0wever, can 6e affected 6y 119and red15tr16ut10n (d15pr0p0rt10nat10n) and f0rmat10n 0f the h0- m01ept1c 5y5tem (5ect 5.3) A repre5entat1ve 5e1ect10n 0f th15119and type 15 5h0wn (F19 13), c0mpr151n9 N,N -615(tert-6uty1)91y0xa1d11m1ne [(dad)L1] [211], N-150- pr0py1-2-(150pr0py1am1n0)tr0p0n1m1ne [(1Pr)2at1] [212], 5u65t1tuted 6en2am1d1- nate5 [213], 5u65t1tuted tr15(pyra201y1)60rate5 7p-R x [214], (N,0-615(tert-6uty1)

(a1k0xyd1methy1511y1)am1de [215], tr1(tert-6uty1)meth0x1de (tr1t0x) [ 102], 5u65t1- tuted ary10x1de5 [ 137], tr1(tert-6uty1)5110x1de (5110x) [ 102,216] and funct10na112ed 5110x1de 119and5 [217]

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 29

/

4u1re a1ternat1ve r0ute5 t0 av01d 01190mer12at10n 6y 119and 6r1d91n9 [ 116-118] 7he rema1n1n9 Ln(111)-R 60nd, typ1ca11y an a1ky1, hydr1de 0r am1de m01ety, d15- p1ay5 a react1ve 51te wh05e k1net1c pr0f11e can 6e 5ta61112ed up0n var1at10n 0f the 61te an91e and che1ate r1n9 512e 0f the anc111ary 119and, re5pect1ve1y [37] 709ether w1th d1am1de [221,222], 61phen01 0r 81N0L 119and5 [223,224], 5a1en [116] and 5u1f0nam1de 119and5 [118] have 6een d15cu55ed a5 a1ternat1ve 5pectat0r env1r0n- ment5 7he 1atter can ea511y 6e 06ta1ned 1n enant10mer1ca11y pure f0rm 7em- p1ate-type 119and5 5uch a5 cyc100ctatetraeny1 [225] and p0rphyr1n [226] have 6een 5h0wn t0 6e very effect1ve 1n 5ta611121n9 m0n0nuc1ear c0mp1exe5.1n par- t1cu1ar, p0rphyr1n-meta1 m01et1e5 are rather r06u5t and 1e55 m015ture-5en51t1ve Car60rane der1vat1ve5 have 6een emp10yed 60th 1n the f0rm 0f 11th1um -11nked [227] and temp1ate-type 119and5 [228]

7r1va1ent L19and5

C0mp1exe5 der1ved fr0m tr1p1y char9ed 119and5 f0rma11y c0rre5p0nd t0 the h0- m01ept1c tr15(cyc10pentad1eny1) c0mp1exe5 LnCp3.7he5e c0mp0und5 can 6e 0f re1evance 1n Lew15 ac1d cata1y515 where the1r act1v1ty 15 d1rected 6y the f0rmat10n 0f Lew15 ac1d (cata1y5t)/6a5e (5u65trate) pa1r5 [229] Hence, meta1-119and 60nd d15rupt10n and f0rmat10n pr0ce55e5 are pu5hed 1nt0 the 6ack9r0und L1nked cy- c10pentad1eny1-car60rane 119and5 f0rm m0n0nuc1ear c0mm0 (5andw1ched) meta11acar60rane c0mp1exe5 [230] H19h1y funct10na112ed p0date 119and5 5uch a5 tr1am1d0am1ne ( a2atrane ) [231] and tr16en2y1tr1f1u0r0acet0acetate [232] pr0duce f0rma11y 4- and 6-c00rd1nated c0mp1exe5, re5pect1ve1y (F19 15) A d1- nuc1ear c0mp051t10n ha5 6een pr0ven f0r Ln(111) c0mp1exe5 0f the tr1va1ent 011- 905115e54u10xane 119and, 77(0H)3 [233] 7he5e 1nc0mp1ete1y c0nden5ed 119and5

d510

/ • 0 1~ -~ 0

•••••- N -••" 00 , ~, / 81~ 81 / 0 /~1~51 -0-~-51~

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 31

appear t0 6e h19h1y e1ectr0n w1thdraw1n9 and are current1y 6e1n9 5tud1ed a5 m0de15 f0r 5111ca 5urface5 [234]

4.3

1mm061112at10n - ••5upp0rted L19and5••

7he 119and 5phere can a150 6e man1pu1ated 6y 1mm061112at10n (9raft1n9) tech- n14ue5.7he 5urface 0f an 1n0r9an1c 0x1de 0r an 0r9an1c p01ymer then act5 a5 an a1ternat1ve 119and env1r0nment 1mp051n9 5ter1c and e1ectr0n1c c0n5tra1nt5.7he 50-ca11ed heter09en12at10n 0f h0m09ene0u5 cata1y5t5 15 a p0pu1ar meth0d f0r the 9enerat10n 0f hy6r1d cata1y5t5, featur1n9 60th the advanta9e5 0f h0m09ene- 0u5 and heter09ene0u5 cata1y515 [235] F19ure 16 5h0w5 var10u5 type5 0f 5uch 5u- pram01ecu1ar ent1t1e5 wh1ch have 6een 5ucce55fu11y emp10yed 1n cata1yt1c tran5- f0rmat10n5 Ne0dym1um center5 60nded t0 a car60xy1ated d1v1ny16en2ene cr05511nked p01y5tyrene matr1x med1ate the p01ymer12at10n 0f 6utad1ene t0 c15-

1,4-p01y6utad1ene 1n the pre5ence 0f 0r9an0a1um1num rea9ent5 [236] P01ymer- 5upp0rted 5cand1um tr1f1ate ha5 6een emp10yed a5 a reu5a61e cata1y5t 1n 5evera1 fundamenta1 Lew15 ac1d cata1y2ed car60n-car60n 60nd-f0rm1n9 react10n5 5uch a5 a1d01, M1chae1, and Fr1ede1-Craft5 acy1at10n react10n5 [237] and the prepara- t10n 0f d1ver5e 4u1n011ne der1vat1ve5 acc0rd1n9 t0 a three-c0mp0nent c0up11n9 react10n [238] 1mm061112at10n techn14ue5 5uch a5 chem150r6ed p01yacry10n1- tr11e der1vat1ve5 [PA-5c-7AD, p01ya11y1 5cand1um tr1fy1am1de d1tr1f1ate] and m1- cr0encap5u1ated 5cand1um tr1f1ate [MC-5c(07f)3] have 6een u5ed 1n the 1atter hy6r1d 5y5tem the 5c(111) 15 pr06a61y 5ta61112ed 6y n-1nteract10n5 w1th the p01y-

5tyrene 6ack60ne Ch1ra1 p01y5110xane-f1xed eur0p1um ~-d1ket0nate5 were f0und t0 6e reu5a61e cata1y5t5 1n the Dan15hef5ky heter0-D1e15-A1der react10n [239]

Me50p0r0u5 5111cate5 0f type MCM-41 d15p1ay ver5at11e, r191d and therma11y and chem1ca11y r06u5t h05t mater1a15 f0r the 9raft1n9 0f p5eud0-0r9an0meta111c c0mp0und5 5uch a5 511y1am1de5 and a1k0x1de5 (F19 16) [115,240] 7he5e mater1- a15 effect1ve1y cata1y2e car60n-car60n 60nd-f0rm1n9 react10n5 and funct10na1 9r0up tran5f0rmat10n5, a5 5h0wn f0r the Meerwe1n-P0nnd0rf-Ver1ey reduct10n [241] Heter09ene0u5 react10n5 0f 1anthan1de meta15 d15501ved 1n 114u1d amm0- n1a w1th free hydr0xy 9r0up5 0f 5111ca and a1um1na [242] 0r 2e011te5 [243] y1e1ded 5upp0rted 1anthan1de 5pec1e5 wh1ch exh161t cata1yt1c act1v1ty 1n (de-)hydr09en- at10n, 150mer12at10n and M1chae1 react10n5 Lanthan1de am1de and 1m1de m01e- t1e5 have 6een d15cu55ed a5 cata1yt1ca11y act1ve 5urface 5pec1e5

5

React1v1ty Pattern 0f 0r9an01anthan1de C0mp1exe5

7he 1ntr1n51c pr0pert1e5 0f the rare earth cat10n5 a5 revea1ed 6y the1r 0x0ph111c1-

ty, hardne55 , and 1ar9e 512e 90vern the react1v1ty 0f 0r9an01anthan1de c0m- p1exe5 Hence, para11e15 t0 the chem15try 0f a1um1num, the 9r0up 2 and 9r0up 4 e1ement5, and the act1n1de5 are 0ften detected 1n th15 5ect10n the m05t 1mp0r- tant react10n pathway5 0f the5e h19h1y react1ve c0mp1exe5 are 5urveyed w1th rep- re5entat1ve examp1e5 7he 5t01ch10metr1c react10n5 0ut11ned a150 repre5ent the e1ementary 5tep5 1n cata1yt1c react10n 5e4uence5

5.1

D0n0r-Accept0r 1nteract10n5

7he 1nteract10n 0f the hard, Lew15 ac1d1c Ln(111) center5 w1th neutra1 e1ectr0n- d0nat1n9 m01et1e515 a u614u1t0u5 feature 0f 0r9an01anthan1de c0mp1exe5.1n ad- d1t10n t0 the e1ectr0n def1c1ency 0f the 1anthan1de center, 5ter1c un5aturat10n d1- rect5 th15 5ta61112at10n 0f the c0mp1exe5 v1a adduct f0rmat10n

51mp1e Lew15 Ac1d/8a5e-7ype 1nteract10n5

501vent c0mp1exat10n u5ua11y re5u1t5 fr0m 5a1t metathe515 react10n5 wh1ch have 6een carr1ed 0ut 1n etherea1501vent5 5uch a5 7HF 0r DME 501vent c00rd1nat10n a5 a ru1e decrea5e5 the react1v1ty 0f Ln-R 60nd5 6y dep01ar12at10n, 5ter1c 5atura- t10n, and c0mpet1t10n react10n5.0n the 0ther hand, d0n0r c00rd1nat10n 1ead5 t0

an enhanced reduc1n9 a6111ty 0f Ln(11) c0mp0und5 (e.9 HMPA c00rd1nat10n [244] ) Lew15 6a5e c00rd1nat10n 0ften f0rce5 cry5ta1112at10n (e.9 0CPh 2, 0PPh 3, 7MEDA) [E4 (32)] [245,246] and 5tr0n91y d0nat1n9119and5 5uch a5 acet0n1tr11e 0r pyr1d1ne were 5h0wn t0 act a5 denuc1eat1n9 a9ent5 1n cyc10pentad1eny1 and a1k0x1de chem15try [E4.(33)] [20,247] 5u65t1tuted 1m1da201-2-y11dene5, car6ene-type 119and5, f0rm 5tr0n9 adduct c0mp1exe5 w1th Ln(11) and Ln(111) meta1 center5 a5 1nd1cated 6y 7HF d15p1acement [E4 (34)] [248] H0wever, c00r-

Pr1nc1p1e51n 0r9an01anthan1de Chem15try 33

d1nat10n 0f 50ft Lew15 6a5e5 wa5 065erved 1n the ca5e 0f term1na11y 60nded PMe 3 1n a h19h1y e1ectr0ph111c 5cand1um c0mp1ex [E4 (35)] [249] Even water c0m- p1exe5 c0u1d 6e trapped a5 the 1n1t1a1 5tep 0f the hydr01y515 react10n [250] 7he va5t maj0r1ty 0f 0r9an1c tran5f0rmat10n5 med1ated 6y 1anthan1de center5 de- pend 0n pre-c00rd1nat10n 0f a neutra1, funct10na112ed 5u65trate and 5u65e4uent f0rmat10n 0f an act1vated 5pec1e5

Ln[N(51Me3)213 + 0=CPh2 hexane Ln[N(51Me3)213(0=CPh2) (32)

[Dy(0CHt8u)312 + 4CH3CN hexane ~- 2 Dy(0CHt8u)3(CH3CN)2 (33)

Ce[C5H3(51Me3)2-1,313(thf) t01uene, - 7HF A, vacuum ,~ 0e[05H3(51Me3)2-1,313 (36)

n-hexane Ln[N(51HMe2)213(thf)2 + A1Me3 ~ Ln[N(51HMe2)213(thf) + A1Me3(thf) (37)

t01uene Cp*La[CH(51Me3)212(thf) + [Merr1f1e1d p01ymer]-CH251Me21

Cp*La[CH(51Me3)212 + [Merr1f1e1d p01ymer]-CH251Me20(CH2)41

(38)