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“  Create ions (in an ion source).  Look at ions (with a mass spectrometer). resolve m/z, (dissociate), count  Look at ions react (in a reaction cell). 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.  ICP/SIFT tandem mass spectrometer  2003: Suppression of chemical noise in MS, etc. (T. Covey, MDS SCIEX)  NSERC/MDS SCIEX/York Partnership  ESI/qQ/SIFT/QqQ multipole ms

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 __________________________________________________________________________________________________________ An Inductively-Coupled Plasma / Selected-Ion Flow Tube Mass Spectrometer Study of the Chemical Resolution of Isobaric Interferences. G.K. Koyanagi, V.I. Baranov, S. Tanner and D.K. Bohme, J. Anal. At. Spectr. 15, (2000). Argon Plasma 5500 K P = 1 atm Aqueous solution of the atomic salt is injected via a nebulizer into the Ar plasma

Periodic Table of Atomic Salt Solutions

Attractive Features of the ICP Ion Source  intense: ca ions s -1 in first quad (Ar + with 0.1% metal ions), ca ions cm -3 in flow tube  defined: thermal population of electronic states at ca K which relaxes toward 295 K.  rapid: time to change metal ions ca. 30 s  stable: not hours but weeks  versatile: almost universal source of atomic ions

Primary Oxidation and Nitration Nb + + N 2 O  NbO + + N 2  NbN + + NO Further Oxidation NbO + + N 2 O  NbO N 2 NbN + + N 2 O  NbNO + + N 2 Clustering with N 2 O NbO N 2 O  NbO 2 (N 2 O) + NbO 2 (N 2 O) + +N 2 O  NbO 2 (N 2 O) 2 + NbO 2 (N 2 O) 2 + +N 2 O  NbO 2 (N 2 O) 3 + NbNO + + N 2 O  NbNO(N 2 O) + NbNO(N 2 O) + +N 2 O  NbNO(N 2 O) 2 + NbNO(N 2 O) 2 + +N 2 O  NbNO(N 2 O) 3 + Reactions of atomic cations: Nb + with N 2 O ________________________________________________________________ V.V. Lavrov et al., J. Phys. Chem. A 106 (2002) 4581.

59 atomic cations 15 different molecules O 2, NO, N 2 O, NO 2, CO 2, CS 2, OCS, D 2 O, NH 3, CH 4, CH 3 F, CH 3 Cl, SF 6, C 6 H 6, C 6 F 6 Some MO + oxide ions Surfing the Periodic Table

61 atomic cations x 15 molecules = 915 reactions !! Web Data Base

Periodicities in Reactivities

n up to 4 !

k/k c OA (M + ) /kcal mol -1

TS >6.4 x x x D Fe + 1 S Y +  H 0 /(kcal mol -1 ) + + B3LYP/sdd/6-311+G* 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 +. k  r H o (cm 3 s -1 ) (kcal mol -1 ) Cr + (X 6 S) + N 2 O  CrO + ( 4  - ) + N 2 <1.5x Mn + ( 7 S) + N 2 O  MnO + ( 5  ) + N 2 < Co + ( 3 F) + N 2 O  CoO + ( 5  ) + N 2 <1.1x Ni + ( 2 D) + N 2 O  NiO + ( 4  - ) + N 2 <6.3x Mo + ( 6 S) + N 2 O  MoO + ( 4  - ) + N 2 <3.4x Ru + ( 4 F) + N 2 O  RuO + ( 6  + ) + N 2 <3.3x a If overall spin is not conserved, a kinetic barrier is present because 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 Two non-f valence electrons are required for the lanthanide cation to participate in bonding with O. This can be achieved by the promotion of a 4f electron: 4f n 5d 0 6s 1 to 4f n-1 5d 1 6s 1. (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

Ln + + N 2 O  LnO + + N 2 Barriers to Electron Promotion ____________________________________________________ G.K. Koyanagi, D.K. Bohme. J. Phys. Chem. A 105, 8964 (2001)

Arrhenius would be interested! k exp = k c e -PE/RT

Atomic Ions as Catalysts

N 2 O + CO  N 2 + CO 2 O-atom Transport Catalysis N2ON2O N2N2 CO M+M+ MO + CO 2 Need: OA(N 2 ) < OA(M + ) < OA(CO) 40 kcal mol -1 < OA(M + ) < 127 kcal mol -1 No kinetic constraints M + + N 2 O  MO + + N 2 MO + + CO  M + + CO 2

GAUSSIAN98 B3LYP/sdd/6-311+G* V. Blagojevic, G. Orlova, D. K Bohme, J. Am. Chem. Soc. 127 (2005) 3545.

Moderate pressure in the flow tube (0.35 Torr He) Nearly universal source of single charged atomic cations Key features M+M+ Reducing reagent CO Oxidizing reagent N 2 O Establishing a Catalytic Cycle in the Reaction Region MO + Catalytic Cycle

Catalyzed Reduction of N 2 O by CO N2ON2O N2N2 CO M+M+ MO + CO 2 Investigated with 59 cations (26 in the TD window) Observed with10 atomic cations: Ca +, Fe +, Ge + Sr + Ba +, Os +, Ir +, Pt + Eu +, Yb + N 2 O + CO  N 2 + CO 2

59 cations were studied 26 lie in the TD window 10 are catalytic N 2 O + CO  N 2 + CO 2

Observed for: Fe +, Ge + Sr + Ba +, Os +, Ir + Eu +, Yb + N2ON2O N2N2 (2) NO CO M+M+ MO + M+M+ M+M+ NO 2 CO 2 CO Catalytic reduction of N x O y by CO Blagojevic et al. Angew. Chem. Int. Ed. 2003, 42,

N2ON2O N2N2 (2) NO H2H2 M+M+ MO + M+M+ M+M+ NO 2 H2OH2O H2OH2O H2OH2O H2H2 H2H2 Observed for: Ca +,Fe +, Sr +, Os +, Ir + Catalytic reduction of N x O y by H 2

Influence of Ligation

Metal-Cation Ligation on Curved Carbonaceous Surfaces

G.K. Koyanagi, D.K. Bohme. Int.J.MassSpectrom. 227 (2003) 563. Reactions of atomic cations with benzene M + + C 6 H 6  M + (C 6 H 6 )  C 6 H M  MC 6 H H 2  MC 4 H C 2 H 2

M + + C 6 H 6  MC 6 H 6 + M = Fe, Cr, Co MC 6 H O 2  M + + (C 6 H 6 O 2 ) C 6 H 6 + O 2  (C 6 H 6 O 2 ) Catalytic oxidation of benzene catechol Caraiman & Bohme J. Phys. Chem. A 2002, 106,

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 87 Rb + (s 0 ) / 87 Sr + (s 1 ) Interference in age determination of magnetic rocks. L.J. Moens et al, J. Anal. At. Spectrom. 16 (2001) needed Sr + isotope ratios in the presence of a Rb + interference, - used CH 3 F in the dynamic reaction cell, and - measured intensities of SrF + M + + CH 3 F  MF + + CH 3 found to be fast with Sr + (s 1 ) / not with Rb + (s 0 )

The 87 Rb + (s 0 ) / 87 Sr + (s 1 ) Interference Rb + (s 0 ) + CH 3 F  Rb +.CH 3 F100% k  1.3x cm 3 s -1  RbF + + CH 3 0% Sr + (s 1 ) + CH 3 F  Sr +.CH 3 F 4% k = 1.4x cm 3 s -1  SrF + + CH 3 96%

The 87 Rb + (s 0 ) / 87 Sr + (s 1 ) Interference (cont’d) Rb + (s 0 ) + SF 6  NR k  1x cm 3 s -1 Sr + (s 1 ) + SF 6  SrF + + SF 5 97%k = 5.7x cm 3 s -1  SrSF F 3%

ICP/SIFT Results at 295 K, 0.35 Torr He Rb + (s 0 )Sr + (s 1 ) BR k/cm 3 s -1 BR k/cm 3 s -1 M + + CH 3 F  M +.CH 3 F 1 1.3x x  MF + + CH M + + CH 3 Cl  M +.CH 3 Cl 1 5.1x x  MCl + + CH  CH 2 Cl + + MH M + + N 2 O  MO + + N 2 < x M + + CO 2  M +.CO 2 <5x  6x M + + CS 2  M +.CS 2 < x M + + OCS  M +.OCS 1 4.0x x  MS + + CO 0.50 M + + SF 6  MF + + SF 5 < x  MSF F 0.03 M + + D 2 O  M +.D 2 O 1 3.0x x  MOD + + D 0.50 M + + NH 3  M +.NH x x10 -13

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, (2007).

Chemical Reactions of Atomic Metal Dications

Ca ++ + O 3  CaO + + O 2 + (k = 1.5 × cm 3 s -1 ) CaO + + O 3  CaO O 2 (k = 5 × cm 3 s -1 ) CaO O 3  CaO O 2 (k = 6 × cm 3 s -1 ) 100  M CaAcetate in H 2 O/CH 3 OH (1/1) Ozonolysis of Metal Dications Oxidation of Ca ++ is Initiated by Charge Separation.

BaO BaO O3O3 O3O3 BaO BaO Ba(H 2 O)O 3 ++ Ba(H 2 O)O 6 ++ O3O3 O3O3 H2OH2O H2OH2O Ba ++ Ba(H 2 O) ++ Ba(H 2 O) 2 ++ H2OH2O H2OH2O k 1 = 1.1 × cm 3 s -1 k 2 = 2.9 × cm 3 s -1 k 3 = 1.2 × cm 3 s -1 k 4 = 1.8 × cm 3 s  M BaCl 2 in H 2 O/CH 3 OH (1/1) Ba ++  BaO 3 ++  BaO 6 ++  BaO 9 ++  BaO

D 2 O hydrolysis of Ca 2+ Ba 2+ in He at 0.35 Torr and 295 K.

M + RE/eV Products k/ cm 3 s -1 Higher-order Products Mg Mg + + D 2 O + 1.4x10 -9 MgOD +, D 3 O + Ca Ca 2+ D 2 O 2.3x Ca 2+ D 2 O CaOD + + D 3 O + 7.9x CaOD + (D 2 O) 1-5 Sr Sr 2+ D 2 O < 1x Sr 2+ (D 2 O) 2-8 Ba Ba 2+ D 2 O 6.7x Ba 2+ (D 2 O) IE(D 2 O) = 12.6 eV D 2 O Hydrolysis of Metal Dications

Multiply-Charged Metallated Biological Ions

(AGTCTG-5H) 5- k 295 / cm 3 molecule -1 s -1 O 3 < No oxidation O 2 < N 2 O < D 2 O < No hydration C 6 H 6 < No intercalation HBr fast Protonation Hydrobromination  G o acid (HBr) = 1331 kJ mol −1 HBr will protonate H 2 PO 4 − in the gas phase DNA is intrinsically very stable (thanks to Mother Nature)!

Protonation and Hydrobromination of (AGTCTG-5H) 5- by HBr 50  M in 20/80 CH 3 OH/H 2 O

Rate coefficients (in units of cm 3 molecules -1 s -1 ) for reactions with HBr in He at (0.35  0.01) Torr and (292  2) K. Anion k obs k cap k obs /k cap %PT (AGTCTG – 5H) (AGTCTG – 4H) (AGTCTG – 3H) (AGTCTG – 2H) [Ni(AGTCTG – 5H)] 3- > 1 [Ni(AGTCTG – 4H)] 2- > 1 0 The processes observed with nickellated species with HBr were similar to those for non-metallated anions: - 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 N 2 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:

Greg Koyanagi Stefan Feil Janna Anichina Voislav Blagojevic Michael Jarvis Andrea Dasic Tuba Gozet Sara Hashemi Mike Duhig Svitlana Shcherbyna Acknowledgments