摘要：

DALTON J. Chem. Soc., Dalton Trans., 1997, Pages 2557&ndash;2561 2557 Molecular manganese sulfide clusters formed by laser ablation &dagger; Ian G. Dance,* Keith J. Fisher * and Gary D. Willett School of Chemistry, University of New South Wales, Sydney 2052, Australia Laser ablation of solid MnS yields in the gas phase polysulfane cations [MnSn]1 (4 < n < 11), and anionic clusters [MnxSx]2 and [MnxSx11]2 (2 < x < 22), together with clusters [MnxSxO]2 (4 < x < 22) formed from adventitious water.These ions were detected and investigated further by Fourier-transform ion cyclotron resonance mass spectrometry. There are no major discontinuities in abundance or especially stable structures in the series [MnxSx]2 and [MnxSx11]2. There are some differences in the distributions of ions formed by the pink and green forms of solid MnS, with the pink form generating more sulfur vapour and polysulfane cations, and the green form more suitable for the formation of cluster anions.The cations [MnSn]1 lose S2 on collisional activation. The cluster anions [MnxSy]2 are generally unreactive and not oxidised by N2O, but on reaction with H2S (g) they undergo protonation or add one or two S atoms to form also the new products [MnxSx12]2 (4 < x < 8). The compositions [MnxSx]2 and [MnxSx11]2 represent a well defined region of stability for anions, and for the neutral clusters from which they are believed to be formed by electron attachment.As part of our research on metal chalcogenide chemistry and clusters,1&ndash;12 we have a program of investigation of the pristine metal chalcogenide clusters [MxEy] (E = S, Se or Te) free of heteroligands.1&ndash;4,6,11 This is achieved by formation and investigation of these clusters in the gas phase, where they are also devoid of the influences of solvent or crystal environments.10 The results of this work provide fundamental reference data, as well as revealing possibilities for the preparation of new metal chalcogenide clusters and materials in condensed phases.We use the technique of laser ablation (LA) coupled with Fourier-transform ion cyclotron resonance (FTICR) mass spectrometry, which allows all of the main operations of synthesis and characterisation. Synthesis is achieved by association of atoms and ions in a cooling plasma generated by the laser ablation of a solid precursor. The ionised products are collected in an ion trap, monitored mass spectrometrically as a function of time, and purified by removal of unwanted ions from the trap.Selected products thus isolated in the ion trap are further characterised by their reactions with other molecules in the gas phase, and by their dissociative processes: the temporal evolution of the distribution of ions can be monitored throughout. There is a correspondence between these experiments and the conventional investigatory sequence of synthesis &aelig;&AElig; separation/purification &aelig;&AElig; reactivity and reactions.9&ndash;11 The very large number of metal sulfide cluster anions [MxSy]2 which can be generated and investigated this way is striking: by laser ablation of CoS, 83 new anionic molecules containing only Co and S ranging in size up to [Co38S24]2 were detected.4 We have reported also the [MxEy]2 cluster ions formed by iron,4 nickel,1 copper 2 and silver,3 and in this paper we describe the formation, distribution, and reactions of [MnxSy]2 molecular clusters.In previous investigations the distribution of ions [MxEy]2 and their relative abundances were largely independent of the composition of the solid precursor used in the laser ablation, and in some cases mixtures of the relevant elements yield the same distribution of ions [MxEy]2.Thus NiS (s) and Ni3S2 (s) yielded essentially the same spectrum of [NixSy]2; Cu2S (s) and KCu4S3 (s) yielded similar collections of [CuxSy]2, and Cu2Se (s) and a mixture of Cu (s) plus Se (s) gave very similar distributions [CuxSey]2.Therefore we expected that laser ablation of two of the forms of manganese sulfide, green MnS and pink &dagger; Non-SI unit employed: 1 bar = 105 Pa. (metastable) MnS, would yield

展开