Qin Lei, Liu Ruiqin, Sagan Filip, Zhang Zhaoyin, Zhao Lili, Mitoraj Mariusz, Frenking Gernot
State Key Laboratory of Materials-Oriented Chemical Engineering, School of Chemistry and Molecular Engineering, Nanjing Tech University, Nanjing 211816, China.
Department of Theoretical Chemistry, Faculty of Chemistry, Jagiellonian University, R. Gronostajowa 2, 30-387 Cracow, Poland.
Phys Chem Chem Phys. 2024 Sep 25;26(37):24294-24313. doi: 10.1039/d4cp01909a.
Quantum chemical calculations of the anions OAeF (Ae = Be-Ba) have been carried out using methods at the CCSD(T)/def2-TZVPP level and density functional theory employing BP86 with various basis sets. The equilibrium structures have linear geometries for Ae = Be and Mg but they are strongly bent for Ae = Sr and Ba while the calcium species has a quasi-linear structure with a very low bending potential. The calculated bond dissociation energies suggest a record-high BDE of = 144.08 kcal mol for OBeF at the CCSD(T)/def2-TZVPP level, which is the strongest BDE for a dative bond that has been found so far. The BDE of the heavier homologues have a continuously decreasing order for Ae with Be > Mg (113.01 kcal mol) > Ca (84.06 kcal mol) > Sr (72.06 kcal mol) > Ba (60.00 kcal mol). The calculation of the charge distribution reveals a significant charge donation OAe ← F with a declining sequence for the heavier atoms Ae. The oxygen atom in OAeF carries always a higher partial charge than the fluorine atom, which contradicts the standard electronegativities of the atoms. The surprising partial charges are explained with the bonding situation of the atoms in the actual electronic structure. The bonding analysis of the OAe-F bonds using the EDA-NOCV method shows that the bonds have much more electrostatic character than the Ae-F bonds in the diatomic anions. This finding is supported by the results of the LED partitioning approach. The dative interactions have three major and one minor component. The assignment of a quadruple bond for the heavier species with Ae = Ca, Sr, Ba is not reasonable. The driving force for the bent geometries is the accumulation of electronic charge in the lone-pair region at the Ae atoms, which enhances the electrostatic attraction with the other atoms. An adequate description of the bonding situation is given by the formula O-Ae ← F.
已使用CCSD(T)/def2-TZVPP水平的方法以及采用各种基组的BP86密度泛函理论对阴离子OAeF（Ae = Be - Ba）进行了量子化学计算。对于Ae = Be和Mg，平衡结构具有线性几何形状，但对于Ae = Sr和Ba，它们则强烈弯曲，而钙物种具有准线性结构且弯曲势非常低。计算得到的键解离能表明，在CCSD(T)/def2-TZVPP水平下，OBeF的键解离能创纪录地高达144.08 kcal/mol，这是迄今为止发现的配位键中最强的键解离能。较重同系物的键解离能随Ae的顺序持续降低，即Be > Mg（113.01 kcal/mol）> Ca（84.06 kcal/mol）> Sr（72.06 kcal/mol）> Ba（60.00 kcal/mol）。电荷分布的计算揭示了显著的电荷转移OAe ← F，且随着较重原子Ae顺序递减。OAeF中的氧原子总是比氟原子带有更高的部分电荷，这与原子的标准电负性相矛盾。这些令人惊讶的部分电荷可以通过实际电子结构中原子的键合情况来解释。使用EDA-NOCV方法对OAe - F键进行的键合分析表明，这些键比双原子阴离子中的Ae - F键具有更多的静电特征。这一发现得到了LED分区方法结果的支持。配位相互作用有三个主要成分和一个次要成分。将Ae = Ca、Sr、Ba的较重物种指定为四重键是不合理的。弯曲几何形状的驱动力是Ae原子孤对区域电子电荷的积累，这增强了与其他原子的静电吸引力。通过公式O - Ae ← F可以对键合情况进行适当描述。
