同碳雙碳烯及其硼錯合物之合成及探討

Abstract

本論文採用新方法合成兩側取代基相異之同碳雙碳烯，並且將兩側取代基相異之同碳雙碳烯與硼烷-四氫呋喃溶液反應，亦可獲得三配位雙陽離子硼錯合物。 三配位雙陽離子硼錯合物可藉由KC8還原產生意想不到的硼環戊烷結構，具有相當獨特的碳碳單鍵，鍵長可達1.628 #westeur006#，遠較一般碳碳單鍵的1.54 #westeur006#長，理論計算顯示其具有高度穩定的雙自由基共振結構。若將硼環戊烷與S8、三氟甲磺酸銀反應或是以汞燈照射，皆會轉變為原先的三配位雙陽離子硼錯合物，僅陰離子有所不同。 我們也以2-亞甲基苯并咪唑與硼烷-四氫呋喃溶液及三苯硼烷反應，生成含氮雜環烯烴的硼錯合物，並獲得其晶體結構。

We have described a new method to prepare unsymmetrical substituted carbodicarbenes. Reacting unsymmetrical substituted carbodicarbenes with BH3-THF affords the three-coordinate dicationic hydrido boron complexes. The reduction of three-coordinate dicationic hydrido boron complexes by KC8, produced novel boracyclopentanes. The boracyclopentanes contained unique carbon-carbon bonds, with bond length of 1.628 #westeur006#, which is longer than the normal single C(sp3)-C(sp3) bond (1.54 #westeur006#). Computational studies show boracyclopentanes have high stability of the diradical structure. Interestingly, treating boracyclopentanes with S8, silver trifluoromethanesulfonate or UV light would reversibly afford the three-coordinate dicationic hydrido boron complexes. We also treated 2-methylenebenzimidazole derivatives with BH3-THF and triphenylborane, producing N-heterocyclic olefin boron complexes, and obtained their single crystals for X-ray diffraction studies.