Zhang Min, Yuan Rui-Nan, Wu Yan-Bo, Chen Qiang, Wei Zhihong, Li Si-Dian
Shanxi University China
RSC Adv. 2023 Aug 10;13(34):23984-23990. doi: 10.1039/d3ra03930g. eCollection 2023 Aug 4.
Searching for the maximum coordination number (CN) in planar species with novel bonding patterns has fascinated chemists for many years. Using the experimentally observed polyynic cyclo[18]carbon C and theoretically predicted polyynic cyclo[14]carbon C as effective ligands and based on extensive first-principles theory calculations, we predict herein their perfect planar alkaline-metal-centered complexes Cs©C (1) and Na©C (4) which as the global minima of the systems possess the record coordination numbers of CN = 18 and 14 in planar polyynic species, respectively. More interestingly, detailed energy decomposition and adaptive natural density partitioning bonding analyses indicate that the hypercoordinate alkaline-metal centers in these complexes exhibit obvious transition metal behaviors, with effective in-plane (π-6s)σ, (π-7p)σ, and (π-5d)σ coordination bonds formed in Cs©C (1) and (π-3s)σ, (π-3p)σ, and (π-3d)σ coordination interactions fabricated in Na©C (4) to dominate the overall attractive interactions between the metal center and its cyclo[]carbon ligand. Similarly, alkaline-metal-centered planar Cs©CB (2), Cs©C (3), Na©CB (5), and Na©C (6) have also been obtained with CN = 18, 17, 14, and 13, respectively.
多年来，寻找具有新颖键合模式的平面物种中的最大配位数（CN）一直吸引着化学家。以实验观测到的多炔环[18]碳C和理论预测的多炔环[14]碳C作为有效配体，并基于广泛的第一性原理理论计算，我们在此预测了它们完美的平面碱金属中心配合物Cs©C（1）和Na©C（4），作为体系的全局极小值，它们在平面多炔物种中分别具有创纪录的配位数CN = 18和14。更有趣的是，详细的能量分解和自适应自然密度分区键合分析表明，这些配合物中的高配位碱金属中心表现出明显的过渡金属行为，在Cs©C（1）中形成有效的面内（π-6s）σ、（π-7p）σ和（π-5d）σ配位键，在Na©C（4）中形成（π-3s）σ、（π-3p）σ和（π-3d）σ配位相互作用，以主导金属中心与其环[]碳配体之间的整体吸引相互作用。同样，还分别得到了配位数CN = 18、17、14和13的碱金属中心平面Cs©CB（2）、Cs©C（3）、Na©CB（5）和Na©C（6）。
