Formation of the highly unusual cyclic clusters [MH(CO)(4)](n) (M = Mn, n=4-9; M = Re, n = 4-6) under laser desorption/ionisation conditions

The positive and negative ion ultraviolet laser desorption mass spectra of the trinuclear clusters [M3H3(CO)(12)] (M=Mn 1 or Re 2) have been recorded using laser desorption/ionisation time-of-flight mass spectrometry (LDI-TOF -MS). The spectra contain peaks corresponding to trinuclear clusters togeth er with peaks at higher masses arising from the series of condensed product s [MnHn-1(CO)(4n)](-) (where n=4-9). These products are believed to have cy clic structures and to be formed by the stepwise insertion of [MH(CO)(4)] i nto a metal-metal bond.