Mixed-metal carbido carbonyl clusters. Part 1. Synthesis and structural characterization of Di-µ3-acetonitrilecuprio-carbido-ennea-µ-carbonyl-hexacarbonyl-polyhedro-hexarhodium, [Cu2Rh6(CO)15(NCMe)2]·0.5MeOH

Abstract

The title complex has been prepared by direct reaction of the [Cu(NCMe)₄]⁺cation with the [Rh₆C(CO)₁₅]^2– anion in methanolic solution, and characterized by chemical and crystallographic methods. The species [Cu₂Rh₆(CO)₁₅(NCMe)₂].0.5MeOH crystallizes in the monoclinic space group C2/c with cell constants a= 18.21(1), b= 10.509(1), c= 20.69(1)Å, β= 126.00(5)°, and Z= 4. 2 175 reflection intensities, collected by counter methods, have been used to solve and refine the structure down to R 0.041. The molecule contains a prism of rhodium atoms capped on the triangular faces by two Cu(NCMe) linear fragments, and the geometry of the CO ligands is the same as in the parent dianion. The idealized molecular symmetry is D_3h. The Cu–Rh, Rh–Rh, and Rh–C(carbide) mean distances are 2.660, 2.78, and 2.127 Å, respectively. The Cu–Rh bonds have been described in terms of σ and π dative interactions from the rhodium prism to the copper atoms.