Rhodium(I) and Silver(I) Complexes of 4, 5‐Dicyano‐1, 3‐dimesityl‐ and 4, 5‐Dicyano‐1, 3‐dineopentylimidazol‐2‐ylidene |
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| Authors: | Heiko Baier Alexandra Kelling Ralf Jackstell Hans‐Jürgen Holdt |
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| Institution: | 1. Chair of Inorganic Chemistry, Universit?t Potsdam, Karl‐Liebknecht‐Stra?e 24–25, 14476 Golm, Germany;2. Leibniz‐Institut für Katalyse e.V. an der Universitaet Rostock, Albert‐Einstein‐Strasse 29a, 18059 Rostock;3. Germany |
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| Abstract: | The new N‐heterocyclic carbene (NHC) precursors 4, ‐dicyano‐1, ‐dimesityl‐ ( 9 ) and 4, 5‐dicyano‐1, 3‐dineopentyl‐2‐(pentafluorophenyl)imidazoline ( 14 ) were synthesized. The structure of 9 could be determined by X‐ray crystallography. With the 2‐pentafluorophenyl‐substituted imidazolines 9 and 14 , the AgCl(NHC)], RhCl(COD)(NHC)], and RhCl(CO)2(NHC)] complexes NHC = 4, 5‐dicyano‐1, 3‐dimesitylimidazol‐2‐ylidene ( 3 ) and 4, 5‐dicyano‐1, 3‐dineopentylimidazol‐2‐ylidene ( 4 )] were obtained. Crystal structures of AgCl( 3 )] ( 15 ), RhCl(COD)( 3 )] ( 17 ), RhCl(COD)( 4 )] ( 18 ), and RhCl(CO)2( 3 )] ( 19 ) were solved and with the crystal data of 19 , the percent buried volume ( %Vbur) of 31.8(±0.1) % was determined for NHC 3 . Infrared spectra of the imidazolines 9 and 14 and of the complexes 15 – 20 were recorded and the CO stretching frequencies of complexes 19 and 20 were used to determine the Tolman electronic parameters of the newly obtained NHCs 3 (TEP: 2060 cm–1) and 4 (TEP: 2061 cm–1), thus proving that 1, 3‐substitution of maleonitrile‐NHCs does not have a significant effect for the high π‐acceptor strength of these carbenes. |
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| Keywords: | Carbenes Rhodium Silver Tolman electronic parameters Crystal structure Diaminomaleonitrile |
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