MASS-SPECTROMETRY AND DENSITY-FUNCTIONAL STUDIES OF NEUTRAL AND ANIONIC TIN CLUSTERS

The anionic tin clusters Sn-x(-), x = 2-7 have been generated and stud ied using laser ablation Fourier transform ion cyclotron resonance mas s spectrometry (FTICR-MS). Gas phase ion-molecule chemistry has reveal ed that some clusters are reactive towards 2-propanol and hydrogen sul fide and all the clusters are unreactive towards methanol, ethanol, ni trous oxide and methane. Energy minimised structures, obtained from no n-relativistic local spin density functional calculations including po st-SCF non-local energy corrections, were doublets and favoured cyclic or closed structures for x greater than or equal to 3. Inspection of the highest occupied molecular orbitals for the anions revealed signif icant delocalisation of the additional electron, leading to cluster an ions which resemble a sphere, with the charge distributed evenly over all the atoms. Adiabatic electron affinities and atomisation energies determined from energy minimised neutral and anion calculations compar e well with literature values.