Mixed cobalt/gold clusters based on octahedral or prismatic Co6C skeletons

Abstract

The reaction of AuCl(PPh₃) in THF with [Co₆C(CO)₁₅]²⁻1 afforded [Co₆C(CO)₁₅{AuPPh₃}]⁻3, with a metal skeleton consisting of a Co₆C trigonal prism capped by a AuPPh₃ group. 3 incorporated a new AuPPh₃⁺ fragment giving [Co₆C(CO)₁₃{AuPPh₃}₂] 4. The crystal structure of 4 reveals that the metal skeleton consists of a cobalt octahedron with a face capped by an Au₂(PPh₃)₂ unit. The reaction of AuCl(PPh₃) with the anion [Co₆C(CO)₁₃]²⁻, 2 produced the octahedral cluster [Co₆C(CO)₁₃{AuPPh₃}]⁻ in which a face appears to be capped by a AuPPh₃⁺ group according to the crystal structure determination. This compound reacts with an excess of AuPPh₃⁺ to give 4, and produces 3 by reversible reaction with a mild stream of CO. The electrochemical behaviour of these species has been investigated by cyclic voltammetry and coulometry.