Synthetic studies on cobalt carbonyl complexes containing antimony and bismuth. Crystal structures of [SbO(OH){Co(CO)3L}2][L = PPh3 or P(C6H4Me-p)3]

Abstract

The reaction between BiCl₃ and 3 equivalents of K[Co(CO)₃(PPh₃)] affords the complex [Bi{Co(CO)₃(PPh₃)}₃](5). This complex is also formed initially in the corresponding 1:2 reaction, although after longer reaction times [BiCl{Co(CO)₃(PPh₃)}₂](6) is the major product. The reaction between complex (5) and 0.5 equivalents of BiCl₃ also affords (6) demonstrating that (5) is an intermediate in the formation of (6). In addition, (6) and K[Co(CO)₃(PPh₃)] afford (5). These data indicate that, in the reaction with a Co:Bi ratio of 2:1, initially formed (6) rapidly reacts with K[Co(CO)₃(PPh₃)] to give (5) which then slowly undergoes a redistribution reaction with BiCl₃ to give (6). The corresponding 1:1 reaction affords two products, viz.[Bi₂Co₂(CO)₄(PPh₃)₂](13), and [BiCl₂{Co(CO)₃(PPh₃)}](14). All these reactions are discussed and compared with related work in the literature. The reactions between BiCl₃ and K[Co(CO)₄] and also between bismuth metal and [Co₂(CO)₈] are also discussed and compared with relevant literature material. Both reactions afford [Bi{Co(CO)₄}₃](1), and [Bi{Co(CO)₄}₄]^–(2). The reaction between SbCl₃ and 1, 2, or 3 equivalents of K[Co(CO)₃(PPh₃)] affords the complex [Sb₂Co₂(CO)₄(PPh₃)₂](21), analogous to the dibismuth complex (13), via the intermediate [Sb{Co(CO)₃(PPh₃)}₃](20). These reactions are also compared to previous work and a discussion presented of apparent similarities and differences. Oxidation of reaction solutions containing (21) afford the stibinic acid complex [SbO(OH){Co(CO)₃(PPh₃)}₂](23), which has been characterised by X-ray crystallography. The tri-p-tolylphosphine derivatives of (21) and (23) have also been prepared and the latter, [SbO(OH){Co(CO)₃[P(C₆H₄Me-p)₃]}₂](24), also characterised by X-ray crystallography. The results described for bismuth and antimony are compared with the corresponding chemistry known for arsenic and phosphorus.