Organo (dipyridyl) nickel complexes. I. Stability and activation of the alkyl-nickel bonds of dialkyl (dipyridyl) nickel by coordination with various substituted olefins
Organo (dipyridyl) nickel complexes. I. Stability and activation of the alkyl-nickel bonds of dialkyl (dipyridyl) nickel by coordination with various substituted olefins
复制标题
有机（联吡啶）镍络合物。
DOI：
10.1021/ja00743a009
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发表时间：
1971
影响因子：
15
通讯作者：
S. Ikeda
中科院分区：
文献类型：
--
作者：
Takakazu Yamamoto;A. Yamamoto;S. Ikeda
合成了一系列二烷基（联吡啶）镍配合物R_2Ni（dipy）（1，R= CH_3，C_2 H_5，h-C_3 H_5，或z ′-C_4 Ho）。1的热稳定性按CH 3> C2 H5> C3 H7> C4 H9的顺序降低。1的热分解对1为一级反应，（C_2H_5）_2Ni（dipy）的热分解活化能为68 kcal/mol。1与烯烃的反应（四氰基乙烯，马来酸酐，丙烯酰胺，丙烯腈，甲基丙烯腈，丙烯醛，甲基乙烯基酮，丙烯酸甲酯，甲基丙烯酸甲酯，氯乙烯，乙酸乙烯酯，2-乙烯基吡啶，苯乙烯，异丁基乙烯基醚，乙烯，异丙烯，和环辛烯）在室温下导致在大多数情况下的R-Ni键的断裂和形成烯烃配位的络合物的类型Ni（dipy）（烯烃）n（3，= 1或2）。R-Ni键通过烯烃与1的配位而活化，与丙烯腈和丙烯醛的配合物R2 Ni（dipy）（olefin）（2）作为不稳定的中间体分离出来。从红外光谱和电子光谱来看，2和3中的配位烯烃似乎是x键。基于室温下1与烯烃反应的动力学研究，提出了一种涉及2作为中间体形成的机理。具有电负性取代基的烯烃与1形成更强的x络合物，并且比具有较少电负性取代基的烯烃更强烈地活化Ni-R键。在配合物中的电荷转移带的观察允许估计的最高占据的d轨道的能级和溶剂和烯烃配位的金属的效果的研究。提出了1与烯烃相互作用活化Ni-R键的机理。
A series of dialkyl (dipyridyl) nickel complexes R2Ni (dipy)(1, R= CH3, C2H5, h-C3H5, or z'-C4Ho) was prepared. The thermal stability of 1 decreases in the order CH3> C2H5> C3H7> C4H9. Thermal decomposition of 1 is first order with respect to 1, and the activation energy for pyrolysis of (C2H5) 2Ni (dipy) is68 kcal/mol. Reactions of 1 with olefins (tetracyanoethylene, maleic anhydride, acrylamide, acrylonitrile, methacrylonitrile, acrolein, methyl vinyl ketone, methyl acrylate, methyl methacrylate, vinyl chloride, vinyl acetate, 2-vinylpyridine, styrene, isobutyl vinyl ether, ethylene, norbornene, and cyclooctadiene) at room temperature led in most cases to cleavage of the R-Ni bond and to formation of olefin-coordinated complexes of the type Ni (dipy)(olefin)„(3,= 1 or 2). The R-Ni bonds are activated through coordination of the olefins to 1; with acrylonitrile and acrolein the com-plexes R2Ni (dipy)(olefin)(2) were isolated as unstable intermediates. From infrared and electronic spectroscopy, the coordinated olefins in 2 and 3 appear to be x bonded. Based on a kinetic study of the reactions of 1 with olefins at room temperature a mechanism involving the formation of 2 as an intermediate is proposed. Olefins with electro-negative substituents form stronger x complexes with 1 and activate the Ni-R bonds more strongly than those with less electronegative substituents. The observation of charge-transfer bands in the complexes allows estimation of the energy levels of the highest occupied d orbitals and a study of the effect of solvent and olefin coordination to the metal. A mechanism for the activation of Ni-R bonds by interaction of 1 with olefins is proposed.