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.