Thermally and photochemically induced vinyl-hydrogen activation of [η4-1,2:3,4-(trans-1,3,5-hexatriene)](η5-cyclopentadienyl)cobalt: Regio- and stereospecific hydrogen migrations
作者:Joseph A. King、K.Peter C. Vollhardt
DOI:10.1016/0022-328x(94)80169-x
日期:1994.5
[η4-1,2:3,4-(trans-1,3,5-hexatriene)](η5-cyclopentadienyl)cobalt (3) undergoes dimerization to form a flyover carbene, 5, with concomitant elimination of one equivalent of trans-1,3,5-hexatriene. Structure 5 thermally rearranges via a metal-mediated [1,5]-H shift to carbene 6: Ea = 29.1 ± 0.4 kcal mol−1, log A = 11.6 ± 0.6. The structures of 5 and 6 were confirmed by single crystal X-ray determination
[η 4 -1,2-:3,4-(反式-1,3,5-己三烯)](η 5 -环戊二烯基)钴(3)经历二聚化以形成天桥卡宾,5,伴随消去一个当量的的反式-1,3,5-三烯。结构5通过金属介导的[1,5] -H转变为卡宾6而热重排:E a = 29.1±0.4 kcal mol -1,log A = 11.6±0.6。通过单晶X射线测定确认5和6的结构。低温辐照6产生13其经历热诱导的回复至6:E a= 19.4±0.9kcal mol -1,log A= 10.0±1.3。氘标记研究表明,这些CH转化所涉及的机制是分子内,区域和立体特异性的。该系统的化学研究扩展到包括各种同源的CpCo(三烯)配合物。描述了形成这些天桥戊二烯基卡宾的三烯方法与直接卡宾加成之间的比较。