Synthesis, reactivity, electrochemical behavior, and crystal structure of a family of multivalent metal carbido-carbonyl clusters based on the Rh10(C)2Au4-6framework

Six metal carbido-carbonyl clusters have been isolated and recognized as members of a multivalent family based on the dioctahedral Rh10(C)2frame, with variable numbers of CO ligands, AuPPh3moieties, and anionic charge: [Rh10(C)2(CO)x(AuPPh3)y]n-(x = 18, 20; y = 4, 5, 6; n = 0, 1, 2). Anions [Rh10(C)2(CO)18(AuPPh3)4]-([2]-) and [Rh10(C)2(CO)18(AuPPh3)4]2-([2]2-) have been obtained by the reduction of [Rh10(C)2(CO)18(AuPPh3)4] (2) under N2, while [Rh10(C)2(CO)18(AuPPh3)5]-([3]-) was obtained from [Rh10(C)2(CO)20(AuPPh3)4] (1) by reduction under a CO atmosphere. [3]-can be better obtained by the addition of AuPPh3Cl to [2]2-. [Rh10(C)2(CO)18(AuPPh3)6] (4) is obtained from [3]-and 2 as well by the reduction and subsequent addition of AuPPh3Cl. The molecular structures of [2]2-([NBu4]+salt), [3]-([NMe4]+salt), and 4 have been determined by single-crystal X-ray diffraction. The redox activities of complexes 1, 2 and [3]-have been investigated by electrochemical and electron paramagnetic resonance (EPR) techniques. The data from EPR spectroscopy have been accounted for by theoretical calculations. © 2012 American Chemical Society.