摘要:
The reagent [NEt4][10-endo-{Au(PPh3)}-nido-7,8-C2B9H9Me2] has been prepared, and used to synthesise several mixed-metal complexes in which gold atoms are bonded to rhodium. Thus treatment of the gold salt with trans-[RhCl(CO)(PPh3)2] or [Rh2(mu-Cl)2(CO)4] in thf (tetrahydrofuran), in the presence of TIBF4, affords the complexes [RhAu(CO)(PPh3)L(eta5-7,8-C2B9H9Me2)] (L = PPh3 or CO), respectively. Reaction of the gold species with [RhCl(PPh3)3] gives the complex [exo-5,10-{Rh(PPh3)2}-5,10-(mu-H)2-10-endo-{Au(PPh3)}-nido-7,8-C2B9H7Me2], the structure of which has been established by X-ray diffraction. The latter complex in solution exists in equilibrium with a minor isomer [RhAu(PPh3)3(eta5-7,8-C2B9H9Me2)] containing a closo-3,1,2-RhC2B9 cage system. With the rhodium complex [Rh(cod)(PPh3)2][PF6] (cod=cycloocta-1,5-diene), and in the presence of molecular hydrogen, the gold reagent yields a chromatographically separable mixture of [exo-5,10-{Rh(PPh3)2}-5,10-(mu-H)2-10-endo-{Au(PPh3)}-nido-7,8-C2B9H7Me2] and [RhAu2(mu-H)(PPh3)3(eta5-7,8-C2B9H9Me2)]. A single-crystal X-ray diffraction study has established the structure of the rhodium-digold compound. The NMR data (H-1, C-13-{H-1}, P-31-{H-1} and B-11-{H-1}) for the new compounds are reported and discussed in relation to their structures.