Dinuclear complexes with bridging functionalized alkylidene ligands:synthesis of the phosphonium [Fe 2Cp 2(CO) 2(μ-CO){μ-C(CN)PR 3}]SO 3CF 3 and of the phosphinoalkylidene [Fe 2Cp 2(CO) 2(μ-CO){μ-C(CN)PH 2}

Abstract

Replacement of SMe 2 by phosphines PR 3 (PR 3 = PPh 3, PMePh 2, PMe 2Ph, PMe 3, P(CH 2Ph) 3, PPh 2CH 2PPh 2, P(NEt 2) 3) in the sulfonium [Fe 2Cp 2(CO) 2(μ-CO){μ-C(CN)SMe 2}]SO 3CF 3 ( 1) results in the formation of the novel phosphonium salts [Fe 2Cp 2(CO) 2(μ-CO){μ-C(CN)PR 3}]SO 3CF 3. The corresponding reaction of 1 with PH 3 affords a mixture of [Fe 2Cp 2(CO) 2(μ-CO){μ-C(CN)PH 3}]SO 3CF 3 ( 3) and the μ-phosphinoalkylidene [Fe 2Cp 2(CO) 2(μ-CO){μ-C(CN)PH 2}] ( 4). Conversion of 3 to 4 is achieved by deprotonating with NEt 3 and completely reversed upon treatment with HSO 3CF 3. The phosphonium and μ-phosphinoalkylidene complexes have been characterized on the basis of their IR, 31P, 1H and 13C NMR spectra.