Synthesis of Co 2Pt, Co 2Pd and MoPd 2 mixed-metal clusters with the P–N–P assembling ligands (Ph 2P) 2NH (dppa) and (Ph 2P) 2NMe (dppaMe). Crystal structure of [Co 2Pt(μ 3-CO)(CO) 6(μ-dppa)

Abstract

Heterometallic triangular platinum–cobalt, palladium–cobalt and palladium–molybdenum clusters stabilized by one or two bridging diphosphine ligands such as Ph 2PNHPPh 2 (dppa) or (Ph 2P) 2NMe (dppaMe) or by mixed ligand sets Ph 2PCH 2PPh 2 (dppm)/dppa have been prepared with the objectives of comparing the stability and properties of the clusters as a function of the short-bite diphosphine ligand used and of the metal carbonyl fragment they contain. Ligand redistribution reactions were observed during the purification of [Co 2Pd(μ 3-CO)(CO) 4(μ-dppa)(μ-dppm)] ( 4) by column chromatography with the formation of [Co 2Pd(μ 3-CO)(CO) 4(μ-dppm) 2] and the dinuclear complex [(OC) 2 Co(μ-dppa) 2Pd Cl] ( 5). The latter was independently prepared by reaction of [Pd(dppa- P,P′) 2](BF 4) 2 with Na[Co(CO) 4]. Attempts to directly incorporate the ligand (Ph 2P) 2N(CH 2) 3Si(OMe) 3 (dppaSi) into a cluster or to generate it by N-functionalization of coordinated dppa were unsuccessful, in contrast to results obtained recently with related clusters. The crystal structure of [Co 2Pt(μ 3-CO)(CO) 6(μ-dppa)] ( 1) has been determined by X-ray diffraction.