Cleavage of homometallic and formation of heterometallic M–M bonds. Serendipitous syntheses of bimetallic MnPd(μ-PPh2)(CO)4(η2-P–P) (P–P = dppm, dppe, dppf) and polymetallic Mn2Pd2Ag(μ-Cl)(μ-PPh2)2(μ-dppm)(CO)8

Abstract

Condensation of [Mn₂(CO)₈(μ-PPh₂)]⁻ with Pd(II) assisted by Ag(I) leads to cluster disproportionation, viz. Mn₂Pd₂Ag(μ-Cl)(μ-PPh₂)₂(μ-dppm)(CO)₈ and MnPd(μ-PPh₂)(CO)₄(η²-P–P) (P–P = dppm, dppe, dppf). The former shows a distorted bow-tie structure with two heterometallic triangles {AgPdMn} sharing an Ag center. The unexpected phosphide migration across different metals holds the key to the cleavage and formation of metal–metal bonds. The bimetallic complexes are stabilized by all common diphosphines whereas the polymetallic structure is isolated only when supported by dppm. The latter shows three different types of heterometal–metal bonds Ag–Mn (2.6938(4) Å), Ag–Pd (2.7637(1) Å) and Mn–Pd (2.8183(9) Å) (average values).