REACTIVITY, STRUCTURE, AND THERMOCHEMISTRY OF GROUP 8 TRANSITION METAL IONS, COMPLEXES, AND CLUSTERS IN THE GAS PHASE USING FOURIER TRANSFORM MASS SPECTROMETRY

DENLEY BRUCE JACOBSON, Purdue University

Abstract

By using Fourier transform mass spectrometry (FTMS) reactions of the group 8 transition metal ions, complexes, and clusters with hydrocarbons were investigated. Elucidation of reaction mechanisms by determination of ion structures was a major thrust of this research. Ion structures were probed by using collision-induced dissociation (CID), specific ion-molecule reactions, labeled compounds, and H/D exchanges. In many cases, ion structures were unequivocally determined by using a combination of the above techniques.^ The reactions of Fe('+), Co('+), and Ni('+) with aliphatic alkanes proceed nearly exclusively by attacking C-C bonds. FeH('+), CoH('+), NiH('+), CoCH(,3)('+), FeCH(,2)('+), and CoCH(,2)('+), however, react with aliphatic alkanes predominantly by attacking C-H bonds with FeCH(,3)('+) being unreactive. The overall order of reactivity of these metal ions toward alkanes is as follows: FeCH(,2)('+) > Fe('+) > FeH('+) > FeCH(,3)('+); CoCH(,2)('+) (TURN) CoH('+) > Co('+) > CoCH(,3)('+); and NiH('+) > Ni('+).^ A convenient method for in situ synthesis of bare homonuclear and heteronuclear cluster ions in the gas phase using FTMS was developed. This technique involves a two step process in which the first step is an ion-molecule reaction between an atomic transition metal ion and a transition metal carbonyl in which one or more carbonyls are displaced. Next, collisional activation of the resulting ions sequentially strips the remaining carbonyls from the complex producing the bare metal cluster. Dimers generated by this method include VFe('+), Fe(,2)('+), CoFe('+), NiFe('+), CuFe('+), RhFe('+), Co(,2)('+), NiCo('+), CuCo('+), and RhCo('+). The trimeric clusters Fe(,3)('+), Co(,3)('+), FeCo(,2)('+), and NiCo(,2)('+) were also synthesized. ^

Degree

Ph.D.

Subject Area

Chemistry, Inorganic

COinS