Molecular and electronic structure of Tc₂(O₂CCH₃)₂Cl₄ studied by multiconfigurational quantum chemical methods

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• 作者：Tanya K. Todorova ; Frederic Poineau ; Paul M. Forster ; Laura Gagliardi ; Kenneth R. Czerwinski ; Alfred P. Sattelberger
• 关键词：SCXRD ; single crystal X-ray diffraction ; DFT ; density functional theory ; CASPT2 ; Complete Active Space Second-order Perturbation Theory ; EBO ; effective bond order
• 刊名：Polyhedron
• 出版年：9 March, 2014
• 年：2014
• 卷：70
• 期：Complete
• 页码：144-147
• 全文大小：740 K

文摘

The molecular and electronic structure, as well as the electronic absorption spectrum of Tc₂(O₂CCH₃)₂Cl₄ were studied by multiconfigurational quantum chemical methods. The computed ground state geometry is in excellent agreement with the experimental structure determined by single crystal X-ray diffraction (SCXRD). The total bond order (i.e., 3.20) is consistent with the presence of a moderately strong quadruple Tc-Tc bond and is the largest bond order reported so far for a multiple Tc-Tc bonded complex. Effective bond order analysis indicates stronger 蟺 and 未 bonds for Tc₂(O₂CCH₃)₂Cl₄ (i.e., 1.71 for 蟺 and 0.59 for 未) than for Tc₂Cl₈^{2鈭?/sup> (i.e., 1.68 for 蟺 and 0.47 for 未). The electronic absorption spectrum was recorded in dichloromethane and shows three distinct bands in the range 10 000-35 000 cm鈭?. Assignment of the bands, as well as their excitation energies and intensities were performed at the CASSCF/CASPT2 level of theory. The lowest energy band corresponds to the 未 鈫?#xA0;未鈭?/sup> transition; the next higher energy bands are attributed to 未 鈫?#xA0;蟺鈭?/sup> and 蟺 鈫?#xA0;未鈭?/sup> transitions, respectively.}