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• 作者：Jens Niklas ; Mark Westwood ; Kristy L. Mardis ; Tiara L. Brown ; Anthony M. Pitts-McCoy ; Michael D. Hopkins ; Oleg G. Poluektov
• 刊名：Inorganic Chemistry
• 出版年：2015
• 出版时间：July 6, 2015
• 年：2015
• 卷：54
• 期：13
• 页码：6226-6234
• 全文大小：410K
• ISSN：1520-510X

文摘

The Ni(I) hydrogen oxidation catalyst [Ni(P^Cy₂N^tBu₂)₂]⁺ (1⁺; P^Cy₂N^tBu₂ = 1,5-di(tert-butyl)-3,7-dicyclohexyl-1,5-diaza-3,7-diphosphacyclooctane) has been studied using a combination of electron paramagnetic resonance (EPR) techniques (X-, Q-, and D-band, electron鈥搉uclear double resonance, hyperfine sublevel correlation spectroscopy), X-ray crystallography, and density functional theory (DFT) calculations. Crystallographic and DFT studies indicate that the molecular structure of 1⁺ is highly symmetrical. EPR spectroscopy has allowed determination of the electronic g tensor and the spin density distribution on the ligands, and revealed that the Ni(I) center does not interact strongly with the potentially coordinating solvents acetonitrile and butyronitrile. The EPR spectra and magnetic parameters of 1⁺ are found to be distinctly different from those for the related compound [Ni(P^Ph₂N^Ph₂)₂]⁺ (4⁺). One significant contributor to these differences is that the molecular structure of 4⁺ is unsymmetrical, unlike that of 1⁺. DFT calculations on derivatives in which the R and R鈥?groups are systematically varied have allowed elucidation of structure/substituent relationships and their corresponding influence on the magnetic resonance parameters.