Heterometallic Complexes with Re−Bi Metal Bonds

The reaction of rhenocene hydride with bismuth alkoxides leads to complexes containing Re−Bi metal bonds with concomitant formation of the corresponding alcohols. Hence, compounds of the type [Cp2Re−BiR2] can be obtained from the monoalkoxide [(MeO)Bi(o-tol)2]n and also from the trialkoxide [Bi{OCH(CF3)2}3(thf)]2, for which in principle also multiple substitution reactions would have been possible, but are prohibited by the electron-withdrawing character of the hexafluoroisopropyl groups. Correspondingly, the trialkoxide [Bi(OtBu)3] containing electron-rich tert-butyl groups does lead to multiple substitution events: First of all it reacts with two equivalents of [Cp2ReH] to give the intermediate [(Cp2Re)2Bi(OtBu)], which could not be isolated, since it undergoes an intramolecular alcohol elimination via CpC−H bond cleavage. This results in the complex [CpRe(μ-η5,η1-C5H4)Bi−ReCp2], featuring a bent Bi−C bond so that one deprotonated Cp ligand bridges a Bi−Re metal bond. All compounds have been fully characterized, and their crystal structures are discussed.