Heterotetrametallic Re-Zn-Zn-Re Complex Generated by an Anionic Rhenium(I) β-Diketiminate.

We report the synthesis of an anionic rhenium(I) compound, Na[Re(η5-Cp)(BDI)] (1; Cp = cyclopentadienide, BDI = N, N'-bis(2,6-diisopropylphenyl)-3,5-dimethyl-β-diketiminate) and initial investigations of its use as a strong chemical reductant and metalloligand. Chemical oxidation of 1 gives a rare example of a rhenium(II) compound Re(η5-Cp)(BDI) (2), while protonation of 1 yields the rhenium(III) hydride complex Re(H)(η5-Cp)(BDI) (3). The reaction of 1 with ZnCl2 generated both 2 and the zinc(I) compound [ZnRe(η5-Cp)(BDI)]2 (4), which features a linear, tetrametallic Re(I)-Zn(I)-Zn(I)-Re(I) core. Computational studies of 4 were performed to characterize the metal-metal bonding interactions; the results indicate a dative interaction from rhenium to zinc and covalent bonding between the two zinc centers. One-electron oxidation of 4 yielded both 2 and the triflate-bridged zinc(II) complex [(μ-OTf)ZnRe(η5-Cp)(BDI)]2 (5, OTf = trifluoromethanesulfonate).