Synthesis and Characterization of Dimethylbis(2-pyridyl)borate Nickel(II) Complexes: Unimolecular Square-Planar to Square-Planar Rotation around Nickel(II)

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• 作者：Jeff A. Celaje ; Megan K. Pennington-Boggio ; Robinson W. Flaig ; Michael G. Richmond ; Travis J. Williams
• 刊名：Organometallics
• 出版年：2014
• 出版时间：April 28, 2014
• 年：2014
• 卷：33
• 期：8
• 页码：2019-2026
• 全文大小：398K
• 年卷期：v.33,no.8(April 28, 2014)
• ISSN：1520-6041

文摘

The syntheses of novel dimethylbis(2-pyridyl)borate nickel(II) complexes 4 and 6 are reported. These complexes were unambiguously characterized by X-ray analysis. In dichloromethane solvent, complex 4 undergoes a unique square-planar to square-planar rotation around the nickel(II) center, for which activation parameters of 螖H = 12.2(1) kcal mol^鈥? and 螖S = 0.8(5) eu were measured via NMR inversion recovery experiments. Complex 4 was also observed to isomerize via a relatively slow ring flip: 螖H = 15.0(2) kcal mol^鈥?; and 螖S = 鈭?.2(7) eu. DFT studies support the experimentally measured rotation activation energy (cf. calculated 螖H = 11.1 kcal mol^鈥?) as well as the presence of a high-energy triplet intermediate (螖H = 8.8 kcal mol^鈥?).