Reaction of the neutral diniobium benzene complex {[Nb(BDI)NtBu]2(μ-C6H6)} (BDI = N,N′-diisopropylbenzene-β-diketiminate) with Ag[B(C6F5)4] results in a single electron oxidation to produce a cationic diniobium arene complex, {[Nb(BDI)NtBu]2(μ-C6H6)}{B(C6F5)4}. Investigation of the solid state and solution phase structure using single-crystal X-ray diffraction, cyclic voltammetry, magnetic susceptibility, and multinuclear NMR spectroscopy indicates that the oxidation results in an asymmetric molecule with two chemically inequivalent Nb atoms. Further characterization using density functional theory (DFT) calculations, UV-visible, Nb L3,2-edge X-ray absorption near-edge structure (XANES), and EPR spectroscopies supports assignment of a diniobium complex, in which one Nb atom carries a single unpaired electron that is not largely delocalized on the second Nb atom. During the oxidative transformation, one electron is removed from the δ-bonding HOMO, which causes a destabilization of the molecule and formation of an asymmetric product. Subsequent reactivity studies indicate that the oxidized product allows access to metal-based chemistry with substrates that did not exhibit reactivity with the starting neutral complex.
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机译:中性二铌苯络合物{[Nb(BDI)N t sup> Bu] 2(μ-C6H6)}(BDI = N,N'-二异丙基苯-β-二酮)与Ag [B( C6F5)4]导致单电子氧化,生成阳离子二铌芳烃配合物{[Nb(BDI)N t sup> Bu] 2(μ-C6H6)} {B(C6F5)4}。使用单晶X射线衍射,循环伏安法,磁化率和多核NMR光谱对固态和溶液相结构进行的研究表明,氧化会生成具有两个化学上不等价的Nb原子的不对称分子。使用密度泛函理论(DFT)计算,紫外线可见,Nb L3,2-边缘X射线吸收近边缘结构(XANES)和EPR光谱学进一步表征可支持二铌配合物的分配,其中一个Nb原子携带一个一个未成对的电子,不会在第二Nb原子上大量离域。在氧化转化过程中,一个电子从δ键的HOMO中移出,这导致分子不稳定并形成不对称产物。随后的反应性研究表明,氧化产物允许与不显示与起始中性络合物的反应性的底物接触金属基化学物质。
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