SYNTHESIS OF THE NEW TRIIRON CARBYNE COMPLEXES [FE3(MU-3-CX)(MU-CO)3(CP)3] (X=SME, SET, NMEBZ) AND MOLECULAR-STRUCTURE OF THE SME DERIVATIVE

The reaction of the in situ generated radical complex [Fe2(mu-CSR)(mu- CO)(CO)2(CP)2]. with [Fe2(CO)4(Cp)2] under ultraviolet photolysis, lea ds to the novel mu3-carbyne complexes [Fe3(mu3-CSR)(mu-CO)3(Cp)3] (R = Me, 1a; Et, 1b) in about 30% yield. The molecular structure of 1a has been determined by an X-ray diffraction study: orthorhombic, a = 11.4 51(3), b = 13.058(5), c = 12.660(5) angstrom, Z = 4, space group Pnma, R = 0.0426. The molecule consists of a regular iron triangle capped b y a CSMe carbyne ligand. The three carbonyl ligands bridge the Fe-Fe e dges and each iron atom bears a cyclopentadienyl group. The molecule h as crystallographic C(s) symmetry. A similar triiron complex [Fe3{mu3- CN(Me)Bz}(mu-CO)3(CP)3],4, is formed by the reaction of the radical [F e2{mu-[CN(Me)Bz}(mu-CO)(CO)2(CP)2]. with [Fe2(CO)4(CP)2] under the sam e experimental conditions. Compound 1a reacts with MeSO3CF3 to give S- methylation of the mu3-CSMe group affording the cationic complex [Fe3( mu3-CSMe2)(mu-CO)3(CP)3]SO3CF3.