Synthesis and characterisation of novel phosphido- and selenido-substituted ruthenium carbonyl clusters

Abstract

Reaction of the cyclic organophosphorus ligand P4But41 with [Ru3(CO)12] or [Ru4H4(CO)12] under forcing conditions yields a number of novel phosphido- and phosphinidene-substituted ruthenium carbonyl clusters. Three products have been structurally characterised in reasonable yield: [Ru4(CO)8(PBut)4]2, where a square-planar arrangement of four ruthenium atoms is capped above and below the metal-atom plane by two tert-butylphosphinidene ligands, and additionally two µ-phosphinidene ligands bridge two Ru–Ru edges; [Ru5(CO)15(PBut)]3 in which the five ruthenium atoms adopt a square-pyramidal geometry with the square-basal plane capped by a tert-butylphosphinidene ligand; and [Ru6H2(CO)12(PBut)3]4, where the six ruthenium atoms define an octahedron with triply-bridging phosphinidene groups capping three triangular faces. Clusters 2 and 4 were isolated from the thermolysis of compound 1 with the tetraruthenium substrate [Ru4H4(CO)12]; cluster 3 is a product of the thermolysis of 1 with [Ru3(CO)12]. In addition, the cluster [Ru4(µ4-Se)2(CO)8(µ-CO)3]5 has been isolated by the vacuum pyrolysis of [Ru3(CO)12] with Ph2Se2 at 185 °C. Reaction of this cluster with 1,3-bis(diphenylphosphino)propane (dppp) at room temperature affords the triruthenium phosphine-substituted cluster [Ru3(µ3-Se)2(CO)7(dppp)]6. The structures of clusters 5 and 6 have also been established by single crystal X-ray analysis.