| Summary: | The collision-induced dissociation (CID) of transition metal carbonyl clusters have been recorded and presented using the recently developed technique of energy-dependent electrospray ionisation mass spectrometry (EDESI). EDESI has been improved to incorporate breakdown graphs, allowing complete fragmentation data to be presented. EDESI spectra facilitate the assignment of all ligands, and assist in determining the composition of the cluster core. Electron autodetachment was observed upon ligand loss from multiply charged clusters. For certain clusters, a remarkable amount of structural information was extracted. For example, the structure of [{PtRu<sub>5</sub>C(CO)<sub>15</sub>}<sub>2</sub>Pt(CO)<sub>2</sub>]<sup>2-</sup> was correctly predicted from the EDESI spectrum. Photoelectron spectroscopy was carried out on three clusters and selected CID products in the gas phase. The photoelectron spectra for each species revealed a high density of electronic states, and a reduction in electron binding energy was observed on removal of CO ligands. For the dianionic clusters, electron binding energy was approximately zero where electron autodetachment was observed in the EDESI spectra. The gas-phase reactivity of a naked metal cluster has been studied with the use of a Fourier transform ion cyclotron resonance mass spectrometer. A novel “top down” approach has been used to form [CoRu<sub>3</sub>]<sup>-</sup> in the gas phase, by synthesising [PPN][CoRu<sub>3</sub>(CO)<sub>13</sub>] in the condensed phase and using CID in the electrospray ionisation source to strip the cluster of its ligands. The top down approach to gas phase clusters removes the requirement for a custom-built cluster source, and will allow the study of otherwise difficult to produce mixed-metal systems will interstitial ligands. The reactivity of [CoRu<sub>3</sub>]<sup>-</sup> with CH<sub>4</sub> and H<sub>2</sub> has been studied, and with use of tandem mass spectrometry, [CoRuC]<sup>-</sup> (a product of the reaction between [CoRu<sub>3</sub>]<sup>-</sup> and CH<sub>4</sub>) was isolated and further reacted with CH<sub>4</sub>.
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