Applications of fast atom bombardment mass spectrometry (FAB MS) to organometallic and coordination chemistry

Handling considerations for the mass spectrometry of reactive organometallic compounds

Mass spectrometry is a powerful tool in disparate areas of chemistry, but its characteristic strength of sensitivity can be an Achilles heel when studying highly reactive organometallic compounds. A quantity of material suitable for mass spectrometric analysis often represents a tiny grain or a very dilute solution, and both are highly susceptible to decomposition due to ambient oxygen or moisture. This complexity can be frustrating to chemists and analysts alike: the former being unable to get spectra free of decomposition products and the latter often being poorly equipped to handle reactive samples. Fortunately, many creative solutions to such problems have been developed. This review summarizes some key methods for handling reactive samples in conjunction with the various ionization methods most frequently employed for their analysis.

Ionization methods for the mass spectrometry of organometallic compounds

The rapid development of new ionization methods has greatly expanded the ability of mass spectrometry to target diverse areas of chemistry. Synthetic organometallic and inorganic chemists often find themselves with interesting characterization problems that mass spectrometry could potentially find the answer for, but without a guide for choosing the appropriate method of analysis. This tutorial review seeks to provide that guidance via a simple flow chart followed by a brief description of how each common ionization method works. It covers all of the commonly used ionization techniques as well as promising variants and aims to be a resource of first resort for organometallic chemists and analysts tackling a new problem.

Benzo annulated cycloheptatriene PCP pincer iridium complexes

Chemical conversions of a cycloheptatriene iridium pincer complex were studied by NMR and MS techniques as well as DFT calculations.

Electrospray ionization studies of transition-metal complexes of 2-acetylbenzimidazolethiosemicarbazone using collision-induced dissociation and ion-molecule reactions

The complexes of transition-metal ions (M2+, where M = Fe, Co, Ni, Cu, Zn, Cd, and Hg) with 2-acetylbenzimidazolethiosemicarbazone (L) are studied under electrospray ionization (ESI) conditions. The ESI mass spectra of Fe and Co complexes showed the complex ions corresponding to [M+2L-2H]+, and those of Ni and Zn complexes showed [M+2L-H]+ ions, wherein the metal/ligand ratio is 1:2 and the oxidation state of the central metal ion is +3 in the case of Fe and Co and +2 in the case of Ni and Zn. The Cd and Cu complexes showed preferentially 1:1 complex ions, i.e., [M+L-H]+ or [M+L+Cl]+, whereas Hg formed both 1:1 and 1:2 complex ions. During formation of the above complex ions one or two ligands are deprotonated after keto-enol tautomerism, depending on the nature and oxidation state of central metal ion. The structures and coordination numbers of the metal ions in the complex ions were studied by their collision-induced dissociation spectra and ion-molecule reactions with acetonitrile or propylamine in the collision cell. Based on these results it is concluded that Fe, Co, Ni and Zn form stable octahedral complexes, whereas tetrahedral or square planar complexes are formed preferentially for other metals. In addition, the Cu complex showed a [2L+2Cu-3H]+ ion with a Cu-Cu bond.

Analysis of Low Oxidation State Transition Metal Clusters by Laser Desorption/Ionization Time-of-Flight Mass Spectrometry

A variety of homonuclear and heteronuclear transition metal carbonyl clusters have been analyzed by ultraviolet laser desorption/ionization time-of-flight mass spectrometry. The spectra were recorded in negative and positive ion modes, using both linear and reflective techniques. A range of different clusters based on different nuclearities, geometries, and ligand types, which include hydrides, phosphines, nitriles, and cyclopentadienyl ligands and naked main group atoms, were studied. These experiments have allowed us to construct a detailed picture of the technique for the analysis of transition metal carbonyl clusters and their derivatives. In general, extensive reactions are observed, cluster aggregation reactions in particular, and from a comparison of the spectra obtained, some mechanistic inferences concerning the aggregation processes have been drawn.