Spectroscopic and Computational Studies of a Series of High-Spin Ni(II) Thiolate Complexes

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• 作者：Katherine M. Van Heuvelen ; Jaeheung Cho ; Timothy Dingee ; Charles G. Riordan ; Thomas C. Brunold
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：July 19, 2010
• 年：2010
• 卷：49
• 期：14
• 页码：6535-6544
• 全文大小：1024K
• 年卷期：v.49,no.14(July 19, 2010)
• ISSN：1520-510X

文摘

The electronic structures of a series of high-spin Ni(II)-thiolate complexes of the form [PhTt^tBu]Ni(SR) (R = CPh₃, 2; C₆F₅, 3; C₆H₅, 4; PhTt^tBu = phenyltris((tert-butylthio)methyl)borate) have been characterized using a combined spectroscopic and computational approach. Resonance Raman (rR) spectroscopic data reveal that the ν_Ni−SR vibrational feature occurs between 404 and 436 cm⁻¹ in these species. The corresponding rR excitation profiles display a striking de-enhancement behavior because of interference effects involving energetically proximate electronic excited states. These data were analyzed in the framework of time-dependent Heller theory to obtain quantitative insight into excited state nuclear distortions. The electronic absorption and magnetic circular dichroism spectra of 2−4 are characterized by numerous charge transfer (CT) transitions. The dominant absorption feature, which occurs at 18,000 cm⁻¹ in all three complexes, is assigned as a thiolate-to-Ni CT transition involving molecular orbitals that are of π-symmetry with respect to the Ni−S bond, reminiscent of the characteristic absorption feature of blue copper proteins. Density functional theory computational data provide molecular orbital descriptions for 2−4 and allow for detailed assignments of the key spectral features. A comparison of the results obtained in this study to those reported for similar Ni-thiolate species reveals that the supporting ligand plays a secondary role in determining the spectroscopic properties, as the electronic structure is primarily determined by the metal−thiolate bonding interaction.