Enlarging the family of ferrocenylphosphine dinuclear rhodium complexes:: synthesis and X-ray structure of a novel "A-frame"-type trimetallic Rh/Fe/Rh complex

The symmetrically substituted ligand 1,1'-bis[di(5-methyl-2-furyl)phosphino]ferrocene (1) has been obtained from the bromo-phosphine BrP(Fu(Me))(2) and the dilithioferrocene/TMEDA adduct. The quantitative addition of this ferrocene derivative to the tetracarbonyl dimer [(CO)(4)Rh-2{mu-(S'Bu)(2)}] leads, through decarbonylation, to the dinuclear rhodium complex [(CO)(2)Rh-2 {mu-(S'Bu)(2)} {mu-P,P-Fc[P(Fu(Me))(2)](2)}] (2) in high yield. A X-ray structure [orthorhombic, space group P2(1)2(1)2(1); a = 11.2982(2) Angstrom, b = 13.3165(3) Angstrom, c = 27.2687(7) Angstrom] and the solution multinuclear NMR characterization are reported, which show that the rare "quasi-closed bridging" A-frame structure of the complex is rather similar to the one reported for [(CO)(2)Rh-2{mu-(S'Bu)(2)}{mu-P,P-dppf}] in solid state. However, in solution the furyl-containing ferrocenylphosphine complex presents a greater fluxionality, together with an electronic environment at phosphorus very different from the dppf analogue (delta(p) = -10 and 27 ppm, respectively). (C) 2004 Elsevier B.V. All rights reserved.