Unprecedented Large Temperature Dependence of Silver(I)鈥揝ilver(I) Distances in Some N-Heterocyclic Carbene Silver(I) Complex Salts

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• 作者：Margit Kriechbaum ; Johanna H枚lbling ; Hans-Georg Stammler ; Manuela List ; Raphael J. F. Berger ; Uwe Monkowius
• 刊名：Organometallics
• 出版年：2013
• 出版时间：May 24, 2013
• 年：2013
• 卷：32
• 期：10
• 页码：2876-2884
• 全文大小：456K
• 年卷期：v.32,no.10(May 24, 2013)
• ISSN：1520-6041

文摘

Six examples from a series of complex salts containing bis(1,3-dialkylimidazol-2-ylidene)silver(I) cations (with dialkyl = dimethyl, diethyl, methyl, ethyl, diisopropyl) with [PF₆]^{鈭?/sup>, [SbF₆]鈭?/sup>, [ClO₄]鈭?/sup>, or [AgBr₂]鈭?/sup> anions, respectively, were prepared in high yields and characterized by elemental analysis, 1H and 13C NMR spectroscopy, and mass spectrometry. Single-crystal X-ray diffraction experiments reveal unprecedentedly large contractions of the metallophilic Ag(I)鈥揂g(I) distances in the solid-state structures upon cooling. In the salt containing diisopropyl-substituted ligands and [PF₆]鈭?/sup> anions, a contraction from 3.498(8) to 3.180(2) 脜 was observed on cooling from 293(1) to 100(1) K. Photochemical measurements show strong hypsochromic shifts of the emission maxima upon cooling, underlining the metallophilic-based nature of the emission bands. Ab initio calculations show that the strong temperature dependence of the observed Ag鈥揂g distances can be attributed to some extent to both the shallowness and the anharmonicity of the intermetallic interaction potential. The Ag鈥揂g interaction potentials are found to be attractive only when relativity is accounted for in the calculations.}