Boronski Josef T, Crumpton Agamemnon E, Aldridge Simon
Chemistry Research Laboratory, Department of Chemistry, Oxford OX1 3TA, U.K.
Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, 82 Wood Lane, White City, London W12 7TA, U.K.
J Am Chem Soc. 2024 Dec 25;146(51):35208-35215. doi: 10.1021/jacs.4c12125. Epub 2024 Dec 12.
High-valent nickel species are implicated as intermediates in industrially relevant chemical transformations and in the catalytic cycles of metalloenzymes. Although a small number of tetravalent NiX complexes have been crystallographically characterized, higher nickel valence states have not been identified. Here we report a stable, crystalline NiX complex, Ni(BeCp) (; cyclopentadienyl anion (Cp)), formed by the insertion of zerovalent nickel into three Be-Be bonds. This 16-electron species features an inverted ligand field, is diamagnetic, and exhibits symmetry, on account of the lifting of Ni 4-orbital degeneracy in this molecular geometry. Single-crystal X-ray diffraction and quantum chemical calculations both reveal a toroidal band of electron density perpendicular to the axis of the complex, which may be attributed to delocalized, multicenter aromatic NiBe bonding.
高价镍物种被认为是工业相关化学转化和金属酶催化循环中的中间体。尽管少数四价NiX配合物已通过晶体学表征，但更高的镍价态尚未得到确认。在此，我们报告了一种稳定的晶体NiX配合物Ni(BeCp)（环戊二烯基阴离子（Cp）），它是由零价镍插入三个Be-Be键形成的。这个16电子物种具有反转的配体场，是抗磁性的，并且由于在这种分子几何结构中Ni 4轨道简并性的解除而呈现出对称性。单晶X射线衍射和量子化学计算均揭示了一个垂直于配合物轴的环形电子密度带，这可能归因于离域的多中心芳香族NiBe键。
