Rayón Víctor M, Redondo Pilar, Barrientos Carmen, Largo Antonio
Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid, Spain.
J Phys Chem A. 2007 Jul 19;111(28):6345-53. doi: 10.1021/jp0679055. Epub 2007 Jun 20.
A theoretical study of the first-row transition metal dicarbide cations MC2+ (M=Sc-Zn) has been carried out. Predictions for different molecular properties that could help in their eventual experimental detection have been made. Most MC2+ compounds prefer a C2v symmetric arrangement over the linear geometry. In particular, the C2v isomer is specially favored for early transition metals. Only for CuC2+ is the linear isomer predicted to be the global minimum, although by only 1 kcal/mol. In all cases the isomerization barrier between cyclic and linear species seems to be very small (below 2 kcal/mol). The topological analysis of the electronic density shows that most C2v isomers are T-shaped structures. In general, MC2+ compounds for early transition metals have larger dissociation energies than those formed by late transition metals. In most cases the dissociation energies for MC2+ compounds are much smaller than those obtained for their neutral analogues. An analysis of the bonding in MC2+ compounds in terms of the interactions between the valence orbitals of the fragments helps to interpret their main features.
对第一排过渡金属二碳化物阳离子MC₂⁺（M = Sc - Zn）进行了理论研究。已对有助于其最终实验检测的不同分子性质进行了预测。大多数MC₂⁺化合物相比于线性几何结构更倾向于C₂v对称排列。特别是，C₂v异构体对于早期过渡金属尤为有利。只有对于CuC₂⁺，预测线性异构体是全局最小值，尽管仅比其他异构体高1千卡/摩尔。在所有情况下，环状和线性物种之间的异构化势垒似乎非常小（低于2千卡/摩尔）。电子密度的拓扑分析表明，大多数C₂v异构体是T形结构。一般来说，早期过渡金属的MC₂⁺化合物比晚期过渡金属形成的化合物具有更大的离解能。在大多数情况下，MC₂⁺化合物的离解能比其对应的中性类似物的离解能小得多。根据碎片的价轨道之间的相互作用对MC₂⁺化合物中的键合进行分析有助于解释其主要特征。
