Cleavage of Carbon−Carbon Bonds in Alkyl Cyanides Using Nickel(0)

The reaction of the complex [(dippe)NiH]2 (1) with a variety of alkyl cyanides afforded
nickel(0) compounds of the type [(dippe)Ni(η2-RCN)], where R = Me, Et, Pr, iPr, tBu,
cyclopropyl, cyclobutyl, adamantyl (2−9, respectively). When compounds 2−9 were warmed
to yield oxidative addition products, the thermal reaction proceeded only in the case of 2 to
produce [(dippe)Ni(Me)(CN)] (10). Photochemical activation did produce oxidative addition
products from compounds 2−8, which rapidly evolved to the β-elimination products of the
organic moiety in most cases and to the formation of [(dippe)Ni(CN)2] (11). Reaction of 1
with acetonitrile in the presence of BPh3 gives [(dippe)Ni(η2-MeCNBPh3)] (12), which does
not undergo thermal C−CN cleavage upon heating. X-ray crystal structures are reported
for 10−12.

配合物[(dippe)NiH]₂（编号为1）与多种烷基氰发生反应，生成了通式为[(dippe)Ni(η²-RCN)]的零价镍配合物，其中R分别为甲基（Me）、乙基（Et）、正丙基（Pr）、异丙基（iPr）、叔丁基（tBu）、环丙基、环丁基以及金刚烷基，对应产物编号依次为2至9。将配合物2至9加热以制备氧化加成产物时，仅在配合物2的反应体系中发生热反应，生成[(dippe)Ni(Me)(CN)]（编号为10）。光化学活化可从配合物2至8中得到氧化加成产物，此类产物在多数情况下会快速转化为有机片段的β-消除产物，并生成[(dippe)Ni(CN)₂]（编号为11）。配合物1与乙腈在三苯基硼（BPh₃）存在下反应，得到[(dippe)Ni(η²-MeCNBPh₃)]（编号为12），该配合物在加热时不会发生C-CN键的热断裂。本文报道了配合物10至12的X射线晶体结构。