Azofra Luis M, Scheiner Steve
Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain.
Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322-0300, USA.
J Chem Phys. 2015 Jan 21;142(3):034307. doi: 10.1063/1.4905899.
The complexes formed by H2CO, CH3CHO, and (CH3)2CO with 1, 2, and 3 molecules of CO2 are studied by ab initio calculations. Three different types of heterodimers are observed, most containing a tetrel bond to the C atom of CO2, and some supplemented by a CH⋅⋅O H-bond. One type of heterodimer is stabilized by an anti-parallel arrangement of the C=O bonds of the two molecules. The binding energies are enhanced by methyl substitution on the carbonyl, and vary between 2.4 and 3.5 kcal/mol. Natural bond orbital analysis identifies a prime source of interaction as charge transfer into the π*(CO) antibonding orbital. Heterotrimers and tetramers carry over many of the geometrical and bonding features of the binary complexes, but also introduce O⋅⋅O chalcogen bonds. These larger complexes exhibit only small amounts of cooperativity.
通过从头算研究了H2CO、CH3CHO和(CH3)2CO与1、2和3个CO2分子形成的配合物。观察到三种不同类型的异二聚体，大多数含有与CO2的C原子的四元键，有些还辅以CH⋅⋅O氢键。一种异二聚体通过两个分子的C=O键的反平行排列而稳定。羰基上的甲基取代增强了结合能，其变化范围在2.4至3.5千卡/摩尔之间。自然键轨道分析确定相互作用的主要来源是电荷转移到π*(CO)反键轨道。异三聚体和异四聚体保留了二元配合物的许多几何和键合特征，但也引入了O⋅⋅O硫族键。这些较大的配合物仅表现出少量的协同作用。
