measured in the temperature range employed (RT to −105°C). The barrier in the benzannelated complex 12 is greater than in 11. This is consistent with Hoffmann's [2] prediction that an electronic component should contribute to conformational preferences and rotational barriers in carbene complexes of unsymmetrically substituted transition metals.
使用与温度相关的NMR研究,已经研究了
铁的
环庚三烯和三个环庚亚
三烯基络合物的碳
金属键周围的旋转。既不η 1 -cycloheptatrienylidene-η 5 -cyclopentadienyldicarbonyliron
六氟磷酸盐(3),也不1,2-苯并-5-(η 5 -cyclopentadienylcarbonyltri正butylphosphineiron)
环庚三烯(10)显示出任何温度的依赖关系到-105℃。由此得出的结论是,前者可能更喜欢电子上较不受欢迎的(但在空间上更受欢迎)的构象3b,而后者的旋转势垒太小而无法在此温度范围内观察到。两个η 1 -cycloheptatrienylidene-η5 -cyclopentadienylcarbonyltri正butylphosphineiron
六氟磷酸盐(11)和η 1 -4,5- benzocycloheptatrienylidene-η