Carbon–Hydrogen Activation in Zerovalent Bis(1,5-cyclooctadiene) Complexes of the First Row Transition Metals: A Theoretical Study,The Journal of Physical Chemistry A

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Carbon–Hydrogen Activation in Zerovalent Bis(1,5-cyclooctadiene) Complexes of the First Row Transition Metals: A Theoretical Study
The Journal of Physical Chemistry A ( IF 2.7 ) Pub Date : 2018-03-05 00:00:00 , DOI: 10.1021/acs.jpca.7b12435
Jia Hu ₁ , Hao Feng ₁ , Yaoming Xie ₂ , R. Bruce King _{1,

2} , Henry F. Schaefer ₂

Affiliation

Stepwise interaction of first row transition metal atoms with 1,5-cyclooctadiene to give (C₈H₁₂)₂M complexes is studied using the M06-L/DZP density functional method. The experimentally known (C₈H₁₂)₂Ni is the thermodynamically most favorable complex, with a predicted geometry consistent with its experimental structure as determined by X-ray crystallography. The other transition metal atoms from scandium to zinc also interact exothermically with 1,5-cyclooctadiene to give (C₈H₁₂)₂M derivatives, but these exhibit lower symmetry than the S₄ symmetry exhibited by (C₈H₁₂)₂Ni. Carbon–hydrogen activation of CH₂ groups in a C₈H₁₂ ligand is predicted for most systems. Thus, conversion of (η^2,2-C₈H₁₂)₂M to (η^3,2-C₈H₁₁)(η^2,1-C₈H₁₃)M, through a hydride intermediate (η^3,2-C₈H₁₁)(η^2,2-C₈H₁₂)MH, is predicted for scandium, vanadium, chromium, manganese, and cobalt. For titanium with a low-lying empty orbital, further C–H activation through a hydride intermediate (η⁶-C₈H₁₀)(η^2,1-C₈H₁₃)TiH is predicted, leading ultimately to (η⁶-C₈H₁₀)(η^1,1-C₈H₁₄)Ti, in which the hexahapto η⁶-C₈H₁₀ ligand is shown by NICS to be aromatic. These two C–H activation processes on a titanium center represent the dehydrogenation of 1,5-cyclooctadiene to 1,3,5-cyclooctatriene with the second 1,5-cyclooctadiene ligand as the hydrogen acceptor. For zinc C–H activation terminates at (η¹-C₈H₁₁)(C₈H₁₂)ZnH, which has a C–Zn–H three-center bond. No energetically favorable C–H activation processes are predicted for the iron, nickel, and copper (η^2,2-C₈H₁₂)₂M derivatives.

中文翻译：

第一排过渡金属的零价双（1,5-环辛二烯）配合物中的碳氢活化：理论研究

使用M06-L / DZP密度泛函方法研究了第一行过渡金属原子与1,5-环辛二烯的逐步相互作用以生成（C ₈ H ₁₂）₂ M配合物。实验上已知的（C ₈ H ₁₂）₂ Ni是热力学上最有利的配合物，其预测几何形状与其通过X射线晶体学测定的实验结构一致。从钪其它过渡金属原子也锌相互作用放热与1,5-环辛二烯，得到（C ₈ H ^ ₁₂）₂剂M的衍生物，但比这些对称表现出较低的小号₄由（C显示出对称₈ H ₁₂）₂ Ni。预测大多数系统中C ₈ H ₁₂配体中CH ₂基团的碳氢活化作用。因此，（η转化^2,2- -C ₈ ħ ₁₂）₂ M至（η ^3,2 -C ₈ ħ ₁₁）（η ^2,1 -C ₈ ħ ₁₃）M，通过氢化物中间体（η ^{3， 2} -C ₈ ħ ₁₁）（η ^2,2- -C ₈ ħ ₁₂MH，预计用于for，钒，铬，锰和钴。对于通过与低洼空轨道，进一步C-H活化钛的氢化物中间体（η ⁶ -C ₈ ħ ₁₀）（η ^2,1 -C ₈ ħ ₁₃）TIH预测，最终导致（η ⁶ - ç ₈ ħ ₁₀）（η ^1,1- -C ₈ ħ ₁₄）的Ti，其中hexahaptoη ⁶ -C ₈ ħ ₁₀NICS显示该配体是芳族的。这两个在钛中心的CH活化过程代表了1,5-环辛二烯以第二个1,5-环辛二烯配体作为氢受体的脱氢反应为1,3,5-环辛三烯。在锌C-H活化终止（η ¹ -C ₈ ħ ₁₁）（C ₈ H ^ ₁₂）ZNH，其具有C-ZNH三中心键。没有能量上有利的C-H活化方法被预测为铁，镍和铜（η ^2,2- -C ₈ ħ ₁₂）₂剂M的衍生物。

更新日期：2018-03-05

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