Regulation of the Rate of Dinucleation of a Monocopper(I) Complex Containing Bipyrimidine Rotary Units by Restricted Double Pyrimidine Rotation
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- 作者：Yohei Hattori ; Michihiro Nishikawa ; Tetsuro Kusamoto ; Shoko Kume ; Hiroshi Nishihara
- 刊名：Inorganic Chemistry
- 出版年：2014
- 出版时间：March 17, 2014
- 年：2014
- 卷：53
- 期：6
- 页码：2831-2840
- 全文大小：563K
- 年卷期：v.53,no.6(March 17, 2014)
- ISSN：1520-510X
文摘
New copper(I) complexes with coordinated 2-(4鈥?methyl)pyrimidinyl moieties were fabricated, and the isomerism of their pyrimidine ring linkage was investigated. The ligands bis[2-(diphenylphosphino)phenyl] ether (DPEPhos) and 4,4鈥?dimethyl-2,2鈥?bipyrimidine (dmbpm) were used to synthesize a heteroleptic copper(I) complex, [CuI(DPEPhos)(dmbpm)]路BF4 (1路BF4), and a dinuclear copper(I) complex, [(CuI)2(DPEPhos)2(渭-dmbmp)](BF4)2 [2路(BF4)2]. The X-ray crystallographic structures, UV鈥搗is absorption spectra, and luminescence properties of the complexes were analyzed. The thermodynamic and kinetic aspects of the isomerism of 1路BF4 were examined by variable-temperature NMR. Double pyrimidine ring rotation was found to be restricted sterically by the bulky DPEPhos ligands. This limited the number of the possible isomers: 1路BF4 showed only isomers with either one (io isomer) or both (oo isomer) of the two methyl groups positioned away from the copper center, while dinuclear 2路(BF4)2 was only found as a symmetric (io鈥?i>io) isomer, with each of the two methyl groups positioned toward different copper centers. The addition of [Cu(MeCN)2(DPEPhos)] (3路BF4) allowed both isomers of 1路BF4 to form 2路(BF4)2, although at different rates and via different pathways, which were analyzed using time-dependent UV鈥搗is spectroscopy. The io isomer dinucleated more quickly than the oo isomer owing to it being able to form 2路(BF4)2 (i) without bond dissociation and (ii) without a sterically congested ii configuration around the copper center. In contrast, oo-1路BF4 required (i) recombination of the bipyrimidine coordination bonds or (ii) formation of a product with higher thermodynamic energy, unsymmetric (ii鈥?i>oo) 2路(BF4)2. These findings are interpreted as demonstrating a novel kinetic property: a conversion rate determined by pyrimidine ring inversion.