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用从头计算方法研究双核过渡金属化合物Cr_2(O_2CH)_4、MO_2(O_2CH)_4及CrMo(O_2CH)_4的金属—金属多重键性质,计算优化键长与实验值符合很好,原子布居表明Mo_2(O_2CH)_4和CrMo(O_2CH)_4中Mo—Mo、Cr—Mo键分别为σ~2π~4δ~2与σ~2δ~2π~4四重键,同时金属-d与氧和碳-p电子间的电荷重叠对分子稳定有相当贡献。对Cr_2(O_2CH)_4在优化键长下3种组态σ~2δ~2δ~(*2)σ~(*2)、π~4π~(*4)及σ~2δ~2π~4的电子结构、原子布居、总能量及电离能的计算进行比较,讨论了Cr—Cr的成键性质,指出描述Cr—Cr间金属多重键本质必须考虑电子相关效应的影响。
The ab initio calculation method is used to study the metal-metal multiple bond properties of binuclear transition metal compounds Cr_2 (O_2CH) _4, MO_2 (O_2CH) __4 and CrMo (O_2CH) __4. The calculated bond length is in good agreement with the experimental data. The Mo-Mo and Cr-Mo bonds in (O_2CH) _4 and CrMo (O_2CH) _4 are the four bonds of σ ~ 2π ~ 4δ ~ 2 and σ ~ 2δ ~ 2π ~ 4, The charge overlap between the electrons has a considerable contribution to the molecular stability. The electronic structures of Cr_2 (O_2CH) _4 with optimized configurations of σ ~ 2δ ~ 2δ * 2 * σ * 2, π ~ 4π ~ (* 4) and σ ~ 2δ ~ 2π ~ 4 Structure, atomic population, total energy and ionization energy. The bonding properties of Cr-Cr are discussed. It is pointed out that the effect of electron-related effect must be considered when describing the nature of Cr-Cr intermetallic bonds.