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Novel Synthesis, X-ray Crystal Structures, and Spectroscopic Properties of Metalated Hypervalent Phosphorus Compounds, Cp(CO)LFe{P(OC6H4Y)(OC6H4Z)} (L = CO, P(OPh)3, P(OMe)3, PMe3; Y, Z = NH, NMe, O)

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journal contribution
posted on 11.07.1998, 00:00 by Kazuyuki Kubo, Hiroshi Nakazawa, Tsutomu Mizuta, Katsuhiko Miyoshi
Iron phosphorane complexes, (1a, Y = NH; 1b, Y = NMe; 3, Y = O), have been prepared from [Cp(CO)2Fe{P(OPh)3}]PF6, o-HOC6H4YH, and a Lewis base. (2a, R = H; 2b, R = Me) having two different chelates on the phosphorus has been prepared from o-HOC6H4NRH, and a Lewis base. These reactions involve nucleophilic attacks of an organic nucleophile at a trivalent phosphorus coordinated to an iron and substitution on the phosphorus. During the course of preparation of 1b, (4) was isolated, which corresponds to one of the intermediates on the reaction pathways to give 13. 4 reacts with a Lewis base to give 1b. The reaction of hydridophosphorane with n-BuLi leads to NH proton abstraction to give the amide which then reacts with Cp(CO)LFeCl to yield (5, L = P(OPh)3; 6, L = P(OMe)3; 7, L = PMe3) by an apparent 1,2-proton migration. The X-ray structures of 1b, 2b, and 4 were determined. 1b and 2b have slightly distorted trigonal-bipyramidal geometries around the phosphorus with the iron fragment in the equatorial position and have P−Oeq bonds longer than those of organophosphoranes, indicating that the Cp(CO)2Fe fragment serves as a strong π donor. The Fe−P(phosphorane) bond rotates freely in solution even at −50 °C. A Berry pseudorotation around the phosphorane phosphorus does not occur for 1a,b, 2a,b, and 57, whereas it does for 3.

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