A Step beyond the Feltham鈥揈nemark Notation: Spectroscopic and Correlated ab Initio Computational Support for an Antiferromagnetically Coupled M(II)鈥?NO)鈭?/sup> Description of Tp*M(NO) (M =

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• 作者：Neil C. Tomson ; Mark R. Crimmin ; Taras Petrenko ; Lauren E. Rosebrugh ; Stephen Sproules ; W. Christopher Boyd ; Robert G. Bergman ; Serena DeBeer ; F. Dean Toste ; Karl Wieghardt
• 刊名：Journal of the American Chemical Society
• 出版年：2011
• 出版时间：November 23, 2011
• 年：2011
• 卷：133
• 期：46
• 页码：18785-18801
• 全文大小：1424K
• 年卷期：v.133,no.46(November 23, 2011)
• ISSN：1520-5126

文摘

Multiple spectroscopic and computational methods were used to characterize the ground-state electronic structure of the novel {CoNO}⁹ species Tp*Co(NO) (Tp* = hydro-tris(3,5-Me₂-pyrazolyl)borate). The metric parameters about the metal center and the pre-edge region of the Co K-edge X-ray absorption spectrum were reproduced by density functional theory (DFT), providing a qualitative description of the Co鈥揘O bonding interaction as a Co(II) (S_Co = ³/₂) metal center, antiferromagnetically coupled to a triplet NO^{鈥?/sup> anion (S_NO = 1), an interpretation of the electronic structure that was validated by ab initio multireference methods (CASSCF/MRCI). Electron paramagnetic resonance (EPR) spectroscopy revealed significant g-anisotropy in the S = 1/₂ ground state, but the linear-response DFT performed poorly at calculating the g-values. Instead, CASSCF/MRCI computational studies in conjunction with quasi-degenerate perturbation theory with respect to spin鈥搊rbit coupling were required for obtaining accurate modeling of the molecular g-tensor. The computational portion of this work was extended to the diamagnetic Ni analogue of the Co complex, Tp*Ni(NO), which was found to consist of a Ni(II) (S_Ni = 1) metal center antiferromagnetically coupled to an S_NO = 1 NO鈥?/sup>. The similarity between the Co and Ni complexes contrasts with the previously studied Cu analogues, for which a Cu(I) bound to NO0 formulation has been described. This discrepancy will be discussed along with a comparison of the DFT and ab initio computational methods for their ability to predict various spectroscopic and molecular features.}