Atomic Metal Ion Chemistry in the Gas Phase

ICP/SIFT tandem mass spectrometer the universal atomic ion chemical mass spec - Periodicities in Reactivities - The Special Case of Lanthanides - Atomic Cations as Catalysts - Infl

Atomic Metal Ion Chemistry

in the Gas Phase

Diethard K Bohme

Ion Chemistry Laboratory

Department of Chemistry Centre for Research in Mass Spectrometry

Centre for Research in Earth & Space Science

York University, Toronto, Canada

Department of Chemistry Memorial University October 2, 2007

Ernest Rutherford:

“Ions are jolly little beggars, you can almost see them“

resolve m/z, (dissociate), count

Chemical Mass Spectrometry

Chemical Mass Spectrometry at York, since 2000 :

 2000: Invention of ICP/DRC/MS

(S Tanner, V Baranov, then at MDS/SCIEX)

- Dynamic Reaction Cell (DRC) for the chemical

resolution of isobaric interferences in elemental analysis

- requires chemical data base for atomic-ion reactions.

 NSERC/NRC/MDS SCIEX/York Partnership.

 2003: Suppression of chemical noise in MS, etc.

(T Covey, MDS SCIEX)

OUTLINE

1 ICP/SIFT tandem mass spectrometer

(the universal atomic ion chemical mass spec)

- Periodicities in Reactivities

- The Special Case of Lanthanides

- Atomic Cations as Catalysts

- Influence of Ligation

- Chemical Resolution of Atomic Isobars in

ICP/DRC/MS: a Case Study

2 ESI/qQ/SIFT/QqQ multipole mass spectrometer (the ultimate chemical mass spectrometer)

- Chemical Reactions of Atomic Metal Dications

- Multiply-Charged Metallated Biological Ions

1 The Universal Atomic Ion

Chemical Mass Spectrometer

The ICP/SIFT/QqQ instrument

Periodic Table of Atomic Salt Solutions

Attractive Features of the ICP Ion Source

 intense: ca.1011 ions s-1 in first quad (Ar+ with

 defined: thermal population of electronic states

at ca 5500 K which relaxes toward 295 K.

 rapid: time to change metal ions ca 30 s

 versatile: almost universal source of atomic

ions

Surfing the Periodic Table

61 atomic cations x 15 molecules = 915 reactions !!

http://www.chem.yorku.ca/profs/bohme/research/research.html

Web Data Base

Periodicities in Reactivities

G.K Koyanagi et al., J Phys Chem A 106 (2002) 4581.

Reactions of atomic cationswith CO 2

G.K Koyanagi, D.K Bohme, J Phys.Chem A 110 (2006) 1232

Reactions of atomic cationswith N 2 O

V.V Lavrov et al., J Phys Chem A 106 (2002) 4581

(3) (3) (2)

(2) (2) (2) (2) (2) (2) (2)

(2) (2) (3) (2) (4) (3) (2) (2)

M+SF5 No reaction Not measured

(2) (3) (4)

C Ping and D.K Bohme, J Phys.Chem A, in preparation

Reactions of atomic cations with SF 6

1st Row

2nd Row

3rd RowLanthanides

k c

OA (M+) /kcal mol-1

3 F Rh +

Kinetic barrier due to electron interaction during bond

redisposition (conventional activation barrier)

Slow and spin forbidden a

for formation of ground state MO +

a curve crossing is required to change the spin multiplicity so that overall spin can be conserved.

Kinetic Barriers Due to Constraints in Electronic Spin

The special Case of Lanthanides

Ln•+ + XO  [Ln••+ ]*  Ln::O+ + X

4fn5d06s1 to 4fn-15d16s1

(For La + , Ce + , and Lu + , the promotion corresponds to d 2  d 1 s 1 or s 2  d 1 s 1 )

Exothermic reactions controlled by

the availability of valence electrons for bonding

So can expect a correlation between reaction rate and electron promotion energy PE !

X O

Arrhenius would be interested!

kexp= kc e-PE/RT

Atomic Ions as Catalysts

OA(N2) < OA(M+) < OA(CO)

40 kcal mol-1 < OA(M+) < 127 kcal mol-1

No kinetic constraints

M+ + N2O  MO+ + N2

MO+ + CO  M+ + CO2

• Moderate pressure in the flow tube (0.35 Torr He)

• Nearly universal source of single charged atomic cations

Key features

M +

Reducing reagent

CO

Oxidizing reagent

N 2 O

Establishing a Catalytic Cycle in the Reaction Region

Cycle

Investigated with 59 cations (26 in the TD window)

Observed with10 atomic cations:

in range and catalytic

in range but not catalytic

59 cations were studied

26 lie in the

TD window

10 are catalytic

N2O + CO  N2 + CO2

Blagojevic et al.

Angew Chem Int Ed

2003, 42, 4923-4927

Influence of Ligation

H H

H H

H H

H H

Fe

Fe

H H H

H H

H H

H

H H

H

H H H

H H

H H

Fe

FeFe

H

H

+ +

+

+ +

Metal-Cation Ligation

on Curved Carbonaceous Surfaces

2 Adduct 3 Adducts 4 Adducts

G.K Koyanagi, D.K Bohme Int.J.MassSpectrom 227 (2003) 563

Reactions of atomic cations with benzene

0.0 0.2 0.4 0.6 0.8 1.0

0.0 0.2 0.4 0.6 0.8 1.0

Ta

O2 addition O-transfer

ICP/SIFT results for MC6H6 + + O2

D Caraiman, D.K Bohme J Phys Chem A 106 (2002) 97057.

M++ O2

M+

+ O2

0.0 0.2 0.6 0.8

TiBz VBz CrBz +

benzene abstraction ligand switching

NR NA

+ O2

OH

C O + H2O

O O + H2

OH HO

+ O H = 16.8±0.3 kcal mol-1

H = 62.5±2.5 kcal mol-1

H = -44.8±1.1 kcal mol-1

O + O O

O H = 29.5±0.1kcal mol-1

OO

H = 14.4±0.1 kcal mol-1

CHO CHO H = -52.4±0.1 kcal mol

ICP/SIFT/QQQ mass spectrum

Proposed tetrahedral structure for Sr(C 60 ) 4 +

Chemical Resolution

of Atomic Isobars

in ICP/DRC/MS:

a Case Study

A CASE STUDY

The 87Rb+ (s0) / 87Sr+ (s1) Interference

in age determination of magnetic rocks.

L.J Moens et al,

J Anal At Spectrom 16 (2001) 991-994

- needed Sr+ isotope ratios in the presence

The 87Rb+ (s0) / 87Sr+ (s1) Interference (cont’d)

Rb + (s 0 ) + SF 6  NR k  1x10 -13 cm 3 s -1

Sr + (s 1 ) + SF 6  SrF + + SF 5 97% k = 5.7x10 -10 cm 3 s -1

 SrSF 5 + + F 3%

ICP/SIFT Results at 295 K, 0.35 Torr He

C Ping and D.K Bohme, J Phys.Chem A, in preparation.

Discontinuities in reactivity provide an

opportunity for chemical resolution

M + + SF 6

 MF n + + SF 6-n

 M + (SF 6 )

 SF n + + MF 6-n

2 The Ultimate

Chemical Mass Spectrometer

The ESI/qQ/SIFT/QqQ instrument

A – skimmer, B – q0 reaction cell, C extended stubbies, D – extended q0 rod set

_

A novel chemical reactor suited for studies of biophysical chemistry: construction and

evaluation of a selected ion flow tube utilizing an electrospray ion source and a triple

quadrupole detection system G.K Koyanagi et al Int J Mass Spectrom 265, 295-301 (2007)

Chemical Reactions

of Atomic Metal Dications

Ca ++ + O 3  CaO + + O 2 +

(k = 1.5 × 10 -9 cm 3 s -1 )  

CaO + + O 3  CaO 2 + + O 2

(k = 5 × 10 -10 cm 3 s -1 )

CaO 2 + + O 3  CaO 3 + + O 2 (k = 6 × 10 -10 cm 3 s -1 )

Ozonolysis of Metal DicationsOxidation of Ca ++ is Initiated by Charge Separation.

10 M BaCl2 in H2O/CH3OH (1/1)

Ba++  BaO3 ++  BaO6 ++  BaO9 ++  BaO12 ++

1 2 3 4

Ca(D2O)2+

CaOD(D2O)5+CaOD(D2O)4+CaOD(D2O)3+

CaOD(D2O)2+

CaOD(D2O)+CaOD+

M + RE/eV Products k/ cm 3 s -1 Higher-order

Multiply-Charged

Metallated Biological Ions

N

N N N

O

H O

H H

H H

O

H

H H

H H

HN N

H H

N N

O

NH

N N O

H H

OH

NH N N O

H H

- O

O P O

- O

O P O

- O

O P O

acid (HBr) = 1331 kJ mol−1

HBr will protonate H2PO4− in the gas phase

DNA is intrinsically very stable (thanks to Mother Nature)!

Protonation and Hydrobromination of (AGTCTG-5H) 5- by HBr

Rate coefficients (in units of 10-9 cm3 molecules-1 s-1)

for reactions with HBr in He at (0.350.01) Torr and (2922)

- trianion underwent protonation and hydrobromination

- dianion underwent only hydrobromination

We have learned that:

 Periodic trends in the reactivities of atomic metal cations

now can be measured routinely in the absence or presence

of ligands

 These trends are governed by thermodynamics, by

intrinsic barriers, by spin, or by electronic structure

effects

● Atomic cations can catalyze the transport of an O atom

from one molecule to another.

 Atomic metal cations can activate benzene and catalyze its

oxidation

 Atomic metal cations can attach to C 60 and perhaps

catalyze the reduction of N2 O while attached.

 The periodic surveys of atomic-cation reactivity provide

useful data for the application of ICP/DRC/MS

 ESI provides a means to study the reactivities of free and solvated atomic metal dications

 ESI provides a means to measure the reactivities of metallated biological anions.

 DNA-like anions appear to be intrinsically very stable.

 Even the chemistry of metallated DNA-like anions now can be invetigated in the gas phase

and that: