Bond Characterization on a Cr鈥揅r Quintuple Bond: A Combined Experimental and Theoretical Study

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• 作者：Lai-Chin Wu ; Chia-Wei Hsu ; Yu-Chun Chuang ; Gene-Hsiang Lee ; Yi-Chou Tsai ; Yu Wang
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：November 17, 2011
• 年：2011
• 卷：115
• 期：45
• 页码：12602-12615
• 全文大小：1437K
• 年卷期：v.115,no.45(November 17, 2011)
• ISSN：1520-5215

文摘

A combined experimental and theoretical charge density study on a quintuply bonded dichromium complex, Cr₂(dipp)₂ (dipp = (Ar)NC(H)N(Ar) and Ar = 2,6-i-Pr₂鈥揅₆H₃), is performed. Two dipp ligands are bridged between two Cr ions; each Cr atom is coordinated to two N atoms of the ligands in a linear fashion. The Cr atom is in a low oxidation state, Cr(I), and in low coordination number condition, which stabilizes a metal鈥搈etal multiple bond, in this case, a quintuple bond. Indeed, it gives an ultrashort Cr鈥揅r bond distance of 1.7492(1) 脜 in the complex. The bond characterization of such a quintuple bond is undertaken both experimentally by high-resolution single-crystal X-ray diffraction and theoretically by density functional calculation (DFT). Electron densities are depicted via deformation density and Laplacian distributions. Bond characterizations of the complex are presented in terms of topological properties, Fermi hole function, source function (SF), and natural bonding orbital (NBO) analysis. The electron density at the Cr鈥揅r bond critical point (BCP) is 1.70 e/脜³, quite a high value for metal鈥搈etal bonding and mainly contributed from the metal ion itself. The quintuple bond is confirmed with one 蟽, two 蟺, and two 未 interactions by NBO analysis and Fermi hole function. The molecular orbitals (MOs) illustrate that five bonding orbitals are predominantly contributed from the 3d orbitals of the Cr(I) ion. The effective bond order from NBO analysis is 4.60. The detail comparison between experiment and theory will be given. Additionally, three closely related complexes are calculated for systematic comparison.