Reactions of anions [M(CO)3(?5-C5H5)]- with [NiCl2(PPh3)2] in tetrahydrofuran afford paramagnetic, bimetallic complexes [MNi(CO)3(PPh3)2(?5-C 5H5)] [M = Mo (1) or W (2)], and a less stable chromium analogue [M = Cr (3)], as green crystalline solids. Ready cleavage of these bimetallic complexes occurs, as on reaction with CO or Ph2PCH2CH2PPh2, and related reactions of [WRh(CO)3(PPh3)2(?5-C 5H5)] (5) are also presented. An X-ray diffraction study of crystalline (2) [monoclinic, space group P21/c, a = 17.873(9), b = 10.156(6), c = 21.249(7) Å, ß = 105.05(3)°, Z = 4] establishes the structure [(?5-C5H5)(OC)W(µ-CO) 2Ni(PPh3)2] (R = 0.062, R' = 0.087) with semibridging CO groups and a relatively short W-Ni separation [2.574(3) Å]. Spectroscopic studies on complexes (1)-(3) include analyses of e.s.r. spectra both in solution, where coupling to inequivalent 31P nuclei is observed, and in the solid state. Comparative extended-Hückel molecular orbital studies on model complexes [MM'(CO)3(PH3)2(?5-C 5H5)] [M = Mo, M' = Rh; M = W, M' = Ni or Cu (two conformers)] are discussed and the bonding analysed in terms of both direct M-M' and semibridging M(µ-CO)M' interactions. Cyclic voltammetry of complexes (2), (5), and [WCu(CO)3(PPh3)2(?5-C 5H5)] is reported and simple redox processes occur for (2) and (5).
|Number of pages||9|
|Journal||Journal of the Chemical Society, Dalton Transactions|
|Publication status||Published - 1987|