title: A theoretical study on the unusual square-planar structure of bis(imino)pyridine-ligated Group 13 complexes.
abstract: The unusual square-planar (SP) structure of four-coordinate AlIII-complexes with the phenyl-substituted tridentate bis(imino)pyridine (PhI2P) ligand has been studied by a combination of density functional theory (DFT) calculations, frontier molecule orbital (FMO), nucleus-independent chemical shift (NICS) and strain/interaction analyses. The calculations disclose that: (i) the aromaticity shifting from the pyridine ring to the alumina-imidazolate metallacycle, and (ii) the small strain energy imposed on the ligand backbone are two favourable factors for driving the overall SP coordination of the AlIIIion. Meanwhile, the calculations reveal that the SP coordination of the AlIIIion is also influenced by the fourth ligand that is bonded to the AlIIIion. The less steric demanding ligand could ensure the stronger aromaticity of the alumina-imidazolate metallacycle and small strain energy on the ligand backbone. Additionally, the calculations predict that GaIIIand InIIIions favour the SP geometry in the analoguePhI2P-ligated complexes, while BIIIand TlIIIions are reluctant to adopt the SP coordination with thePhI2P ligand. Overall, all of these findings would be helpful for the synthesis of more unknown low-valent main-group metal complexes bearing the bis(imino)pyridine ligand.
authors.affiliation: School of Science, Xihua University, Chengdu, 610039, Sichuan, P. R. China. weiyili@mail.xhu.edu.cn.
authors.forename: Weiyi
authors.initials: W
authors.lastname: Li
authors.affiliation: School of Science, Xihua University, Chengdu, 610039, Sichuan, P. R. China. weiyili@mail.xhu.edu.cn.
authors.forename: Yajing
authors.initials: Y
authors.lastname: Lyu
authors.affiliation: School of Science, Xihua University, Chengdu, 610039, Sichuan, P. R. China. weiyili@mail.xhu.edu.cn.
authors.forename: Huifang
authors.initials: H
authors.lastname: Zhang
authors.affiliation: School of Science, Xihua University, Chengdu, 610039, Sichuan, P. R. China. weiyili@mail.xhu.edu.cn.
authors.forename: Maoqin
authors.initials: M
authors.lastname: Zhu
authors.affiliation: School of Science, Xihua University, Chengdu, 610039, Sichuan, P. R. China. weiyili@mail.xhu.edu.cn.
authors.forename: Hanping
authors.initials: H
authors.lastname: Tang