Converting a perimidine derivative to a cationic N-heterocyclic carbene

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• 作者：Kathrin Verlinden ; Christian Ganter
• 关键词：Perimidine ; N-heterocyclic carbenes ; Rhodium complexes ; Iridium complexes
• 刊名：Journal of Organometallic Chemistry
• 出版年：15 January, 2014
• 年：2014
• 卷：750
• 期：Complete
• 页码：23-29
• 全文大小：577 K

文摘

The synthesis and reactivity of the new cationic N-heterocyclic carbene 6 comprising a Cp*Ru⁺ fragment attached to the aromatic backbone of 1,3-dimethylperimidin-2-ylidene is reported. Carbene 6 forms Rh and Ir complexes of the type [(cod)ClM(6)]⁺ and [(CO)₂ClM(6)]⁺. The analogous complexes of the neutral perimidin-2-ylidene 9 were prepared for comparison purposes. TEP values for both NHCs were calculated from the IR spectra of the carbonyl complexes. The TEP of the cationic carbene 6 (2062聽cm^鈭?) is shifted to higher wavenumbers compared to the neutral derivative 9 (2057聽cm^鈭?) indicating that the former ligand is a poorer overall donor. In addition, DFT calculations revealed a reduced HOMO-LUMO gap for the cationic system suggesting an increased 蟺-acceptor character. Crystal structures of the related complexes [IrCl(cod)NHC(L)] with L聽=聽6 and 9 were determined by X-ray diffraction and show only marginal differences in the geometrical parameters.