Success and serendipity during studies aimed at preparing carbenerhodium(I) complexes

Article abstract of DOI:10.1016/0022-328X(95)00529-Y

The preparation of a series of new square-planar and half-sandwich type carbenerhodium(I) complexes will be described.The key to success is the use of the bis(stibane)rhodium compound trans- as starting material from which in a stepwise manner the complexes trans-, trans- (L = PiPr3, AsiPr3, SbEt3) and (L = SbiPr3, PiPr3, PMe3, CO, CNtBu) have been obtained.Displacement of the carbene ligand in either trans- (L = SbiPr3, PiPr3 or by CO or CNtBu leads to the formation of the corresponding carbonyl- or isocyanidrhodium compounds and the C-C coupling products Ph2C=C=O and Ph2C=C=NtBu, respectively.The carbene ligand is also involved in the selective formation of the isomeric olefins CH2 = CHCPh2H and Ph2C=CHCH3 on treatment of trans- and trans- with ethene.The most spectacular reaction of the bis(triisopropylstibane) complexes, however, occurs on warming of trans- in the absence of any substrate which yields the first representatives of dinuclear transition-metal compounds containing a tertiary stibane ligand in a bridging position.Some exploratory studies on the reactivity of the Rh2(μ-SbiPr3) complexes indicate that the triisopropylstibane can be replaced by SbMe3, SbEt3 or CNtBu without destroying the dimetallic core of the molecule.Keywords: Rhodium; Carbene complexes; Antimony; Stibanes