| Summary: | 碩士 === 國立東華大學 === 化學系 === 99 === In this thesis, we focused on the preparation and investigation of 4,5 substituted imidazolium based N-heterocyclic carbene complexes of gold(I). We divided into three parts to introduce our research: First, 1,10-phenanthro[4,5-f]imidazolium salt prepared from the methylation of Imidazo[4,5-f]-1,10-phenanthrolines by an excellent substrate for SN2 substitution reactions, methyl iodide. Most of substituent group only can substitute one side due to the competition of nitrogen form phenanthrolines. So, we cannot obtain the carbene complexes from this kind of imidazolium salts. Second, phenanthreno[9,10-d]imidazolium salt prepared from the methylation of phenanthreno[9,10-d]imidazole Although there is no other nitrogen to compete alkylation agent, but phenanthrene is a polycyclic aromatic hydrocarbon composed with strong conjugated effect. This strong electron-withdrawing group at the 4,5 position of imidazole decreased the activity of nitrogen on the imidazole. Third, 1,3-Dimethyl-4,5-dicyanoimidazolium salt prepared from the methylation of 1,3-Dimethyl-4,5-dicyanoimidazole by methyl iodide. And complexation of 1,3-Dimethyl-4,5-dicyanoimidazolium to gold(I) carbene complex via Ag2O routes and transmetallation. The structure of the Au(I) carbene complex was investigated by single-crystal X-ray diffraction. The pair of gold(I) carbene complex is associated through the Au-Au [3.408 Å] interactions and the NHC ring pointed in opposite directions. There is no Au-Au [4.532 Å] interaction between the pairs, but the Au atoms of one pair are situated across the NHC ring of the neighboring pair with an Au•••π distance of 3.540 Å. The Au-Au and Au•••π interactions make the structure assemble to form stair-shaped one dimensional structure.
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