Tri- and tetra-nuclear cluster compounds of platinum(0), which contain tertiary phosphines and carbon monoxide

New trinuclear cluster compounds [Pt3(CO)3L4](L = PPh3, PPh2Me, and PPh2Et) and [Pt3(CO)3L3](L = PPh2PhCH2) are obtained by decomposition of the complexes [Pt(CO)2L2]; however their preparation is generally more convenient without the isolation of [Pt(CO)2L2], from an alkali tetrachloroplatinate, a phosphine, and carbon monoxide.Further rearrangement and absorption of carbon monoxide by the trinuclear cluster compounds give the tetranuclear species [Pt4(CO)5L4] and [Pt4(CO)5L3]. The [Pt4(CO)5L4] species have been obtained in two isomeric forms, in the first the carbonyl groups are both terminal and bridging (L = PPh2PhCH2 or AsPh3), and in the second only bridging (L = PPh3 or PPhMe2).Some unusual properties of these cluster compounds, such as lability and associated variability in the co-ordination numbers, are noted.