Synthesis, structure and possible formation pathway of a novel cobalt carbonyl compound with new type BO bond, Co(CO)3(PPh3)2BEt3, and mixed metal CoFeS cluster with possible nonlinear optical property, [Et4N][CoFe2(CO)8S(PPh3)]

Reaction of Co(CNS)2 with Fe2S2(CO)6, LiBEt3H and PPh3 in THFMeCN resulting in a novel cobalt carbonyl complex, Co(CO)3(PPh3)2BEt3 (1) and mixed-metal CoFeS cluster compound, [Et4N][Fe2Co(CO)8S(PPh3)] (2). The structures of 1 and 2 were determined from X-ray three dimension data. Structure studies reveal that 1 is a new cobalt carbonyl complex containing a novel BO bond of 1.601(5) Å in which the oxygen atom is from metal carbonyl and the B atom is from BEt3 and 2 contained a triangular pyramid mixed-metal CoFeS core [CoFe2S]− with CoS of 2.189, FeS of 2.208, CoFe of 2.56 and FeFe of 2.58 Å. Theoretical calculation on 1 and 2 shows that BO bonding energy of complex 1 is lower than that of normal covalent bonding and 2 possesses a calculated nonlinear optical first molecular hyperpolarizability component of 28.5×10−30 esu. The possible formation pathway of 1 and 2 was discussed.