CLEAVAGE OF AN ACYCLIC P-5 LIGAND INTO P-4-VERTICAL-BAR-P-1 AND P-3-VERTICAL-BAR-P-2 MOLECULAR BUILDING-BLOCKS

The cothermolysis of [CpFeP5] (1) and [Cp '' Ta(CO)(4)] (2), Cp '' = (C5H3Bu2)-Bu-t - 1,3, affords the trinuclear cubane-like compounds 3 i n the form of the equilibrium mixture [(CpFe)(Cp '' Ta)(2)P-5] (3a) r eversible arrow [(CpFe)(Cp '' Ta)(2)(P-4)(P-1)] (3b) and small amount s of the P-n complexes [(CpFe)(Cp '' Ta)(P-5)] (4), [(Cp '' Ta)(3)(P- 4)(P-2)] (5), and [(Cp '' Ta)(4)(P-3)(2)] (6). Further reaction of 3a, b with [Mo(CO)(5)(thf)] gives exclusively [(CpFe)(Cp '' Ta)(2)(P-5)(M o(CO)(5)}] (7). The skeleton of 7 consists of an FeP5, six-membered ri ng capped by two {Cp '' Ta} fragments. The formal insertion of a {Cp ' ' Ta(CO)(2)} unit into the intact P-5 chain of 1 provides [(CpFe)(Cp '' Ta)(Cp ''(OC)(2)Ta)(P-3)(P-2)] (9), a trinuclear species where the intact P-5 chain of the educt 3 has been cleaved into a P-3 and a P-2 ligand. 7 and 9 have been further characterized by X-ray crystal struc ture analyses.