A New N-Heterocyclic (NHC) Biscarbene Ligand: Synthesis and Catalytic Activities of Bis-gold(I) Complex and Bis-iridium(I) Complexes

本論文探討新型飽和含氮雜環雙碳烯金屬錯合物的合成、結構解析以及其催化的應用。雙鎢錯合物之雜環氮上烷基化得到氮取代雙鎢錯合物，遂利用已開發的方法將含氮雜環碳烯骨架從鎢金屬轉移至金和銥金屬，分別得到雙金碳烯錯合物和雙銥碳烯錯合物。 將重氮化合物與三苯基膦反應形成膦亞胺中間體，遂與六羰鎢[W(CO)6]藉由兩次分子內環化而得到雙碳烯鎢金屬錯合物，藉由X光單晶繞射分析其晶體結構。雙鎢錯合物之雜環氮上烷基化得到氮取代雙鎢錯合物，將其和[ClAu(Me2S)]反應得到雙金錯合物，藉由質譜分析，其結構為一價金被兩個碳烯所鍵結，形成一穩定錯合物，卻降低其催化活性。另一方面，氮取代雙鎢錯合物與[Ir(COD)Cl]2反應，經由碳烯與羰基同時轉移至銥金屬，即合成出一雙銥錯合物，藉由HR-FAB證實其分子式。藉由三苯基膦置換銥中心的羰基和氯基，順利得到碳烯銥金屬錯合物之雙膦衍生物，藉由X-ray單晶繞射確定其結構。 雙銥錯合物可以應用於氫轉移反應的催化劑，特別是利用醇與胺化物反應的N-烷基化，均展現其優良的催化活性。雙銥錯合物催化對位和間位苯二胺的N-烷基化反應上，相較單核碳烯銥金屬錯合物或其他銥金屬錯合物具有較高的選擇性與活性。因此藉由雙銥錯合物的催化，可以成功從苯二胺與醇類分子製備對應的雙二級胺產物。相似條件下，於鄰位苯二胺的N-烷基化反應會直接由分子內環化得到2-苯基苯并咪唑(2-phenylbenzimidazole)；若於反應環境中使用氫氣，可以抑制分子內環化，而成功得到鄰苯二胺的雙二級胺產物。除了使用苯甲醇外，各類醇類也能用於此系統上。除此之外，雙銥錯合物也能催化含氮雜環之二級胺的N-烷基化反應得到三級胺產物。In this work, we have synthesized gold(I) and iridium(I) metal complexes containing a new bis-N-heterocyclic carbene donor. The desired complexes were obtained via a known carbene-transfer method. Thus, reaction of the bis-azido compound m-C6H4(CH2NHCH2CH2N3)2 (2) with triphenylphosphine followed by the treatment of W(CO)6 yielded the bis-carbene tungsten complex 4 and the structure was further confirmed by X-ray crystal structural determination. Alkylation of 4 with benzyl bromide provided the N-substituted NHC complex 5. Upon the reaction of the N-substituted NHC complex with [(Me2S)AuCl], the carbene fragment readily transferred from tungsten to the gold center and provided a bis-gold complex 6. A bis-Ir(I) carbene complex 7 was prepared via the reaction of 5 with [Ir(COD)Cl]2. Substitution of 7 with triphenylphosphine yielded the bis-phosphine iridium carbene complex 8. Complex 8 was confirmed by X-ray crystal structural analysis to illustrate a bis-iridium frame-work of the complex. Employment of these bis-iridium carbene complexes on the catalytic N-alkylation of phenylenediamines with various alcohols was examined. It appears that the iridium carbene complex 7 shows good catalytic activity on this N-alkylation reaction. Furthermore, N-alkylation of heterocyclic amine with benzyl alcohols could be achieved by the similar catalytic conditions