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 bromophosphine BrP(FuMe)2 and the dilithioferrocene/TMEDA adduct. The quantitative addition of this ferrocene derivative to the tetracarbonyl dimer [(CO)4Rh2{μ-(StBu)2}] leads, through decarbonylation, to the dinuclear rhodium complex [(CO)2Rh2{μ-(StBu)2}{μ-P,P-Fc[P(FuMe)2]2}] (2) in high yield. A X-ray structure [orthorhombic, space group P212121; a=11.2982(2) Å, b=13.3165(3) Å, c=27.2687(7) Å] 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)2Rh2{μ-(StBu)2}{μ-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 (δP=−10 and 27 ppm, respectively).