Reaction of [Rh2{µ-1,8-(NH)2C10H6}(CO)2(PPh3)2] with [M(PPh3)]+(M = Au, Ag, or Cu): formation of unusual 44-electron Rh2M clusters. Crystal structure of [Rh2{µ-Au(PPh3)}{µ-1,8-(NH)2C10H6}(CO)2(PPh3)2]ClO4·2CH2Cl2

Abstract

The complex trans-[Rh₂{µ-1,8-(NH)₂C₁₀H₆}(CO)₂(PPh₃)₂](1) reacts with [M(PPh₃)]⁺(M = Au, Ag, or Cu) to give [Rh₂{µ-M(PPh₃)}{µ-1,8-(NH)₂C₁₀H₆}(CO)₂(PPh₃)₂]ClO₄(2)–(4). Compound (2) was analysed by single-crystal X-ray diffraction: triclinic, space group Pa= 14.358(4), b= 20.775(6), c= 13.184(3)Å, α= 105.65(3), β= 115.66(2), γ= 69.96(3)°, Z= 2, and R= 0.071. The basic skeleton consists of a Rh₂Au triangle, the two Rh–Au distances [2.797(2) and 2.690(2)Å] being consistent with Rh–Au bonds. The co-ordination geometry around the rhodium atoms is square pyramidal. The Rh–Rh separation [2.815(2)Å] is at the upper part of the range of distances for a single Rh–Rh bond. Phosphorus-31 n.m.r. and i.r. data for compounds (2)–(4) are described, and are consistent with a bridging disposition of the M (PPh₃) group in all the complexes.