Coordination and reduction of isocyanide ligands in hydrido-carbonyl rhenium cluster chemistry. Synthesis and characterization of the anion [Re3(μ-H)4(CO)9(CNR)]- and of the formimidoyl derivative [Re3(μ-H)3(CO)9(μ-η2-C(H)NR)(PMe2Ph)]- (R = C6H11)

The reaction of the unsaturated anion [Re3(μ-H)4(CO)9(NCMe)]- with cyclohexylisocyanide gives the novel unsaturated anion [Re3(μ-H)4(CO)9(CNC6H11)-. By reaction of this species with dimethylphenylphosphine a saturated compound is obtained, [Re3(μ-H)3(CO)9(μ-η2-C(H)NC6H11)-(PMe2Ph)]-, containing a bridging formimidoyl ligand. Two isomers of this anion have been identified and the structure of one of them has been elucidated by X-ray analysis. The anion contains an isosceles triangle of Re atoms with two longer hydrogen-bridged edges [mean 3.255 Å] and one shorter edge [3.164(1) Å], doubly bridged by the formimidoyl ligand and the third hydride. The phosphine ligand is coordinated in the axial direction with respect to the Re3 plane, with a ReP bond length of 2.454(7) Å. © 1990.