Hayashi Nobuyuki, Ujihara Tomomi, Anada Masahiro
Institute of Food Research, National Agriculture and Food Research Organization (NARO), 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
Faculty of Pharmacy, Musashino University, 1-1-20 Shinmachi, Nishitokyo, Tokyo 202-8585, Japan.
J Phys Chem A. 2024 Apr 25;128(16):3051-3061. doi: 10.1021/acs.jpca.3c07880. Epub 2024 Apr 16.
In order to elucidate the origins of the stable structures of dirhodium(II) tetrakis[-phthaloyl-()--leucinate] and the four derivatives with halogenated aromatic rings, the conformational stability and intramolecular interactions were investigated by DFT calculations. In all of these complexes, the conformation in which all ligands face in the same direction is the most stable. When adjacent ligands are in the same orientation, destabilization due to exchange repulsion is larger than that when they are in opposite orientations. However, this destabilizing effect is reversed by the sum of the stabilizing effects of the electronic and charge transfer interactions. The imide carbonyl group plays an important role in these stabilizing interactions. The negatively charged site and bond orbitals in the imide carbonyl group interact with the positively charged sites and bond orbitals in the aromatic ring, the carboxylate group, and the α-position of the carboxylate group in the adjacent ligands. In addition, the lone-pair orbitals of the halogen atoms contribute to conformational stabilization by interacting with the vacant orbitals in the adjacent ligands. However, the combinations of these charged sites or bond orbitals, which effectively contribute to the stabilization, are different for each complex.
为了阐明二铑（II）四[-邻苯二甲酰基-（）--亮氨酸酯]及其四种含卤代芳环衍生物的稳定结构的起源，通过密度泛函理论（DFT）计算研究了其构象稳定性和分子内相互作用。在所有这些配合物中，所有配体朝同一方向的构象是最稳定的。当相邻配体处于相同取向时，由于交换排斥引起的去稳定化作用大于它们处于相反取向时的情况。然而，这种去稳定化作用被电子和电荷转移相互作用的稳定化作用之和所逆转。酰亚胺羰基在这些稳定化相互作用中起重要作用。酰亚胺羰基中的带负电位点和键轨道与相邻配体中芳环、羧酸盐基团以及羧酸盐基团α位中的带正电位点和键轨道相互作用。此外，卤原子的孤对轨道通过与相邻配体中的空轨道相互作用而有助于构象稳定。然而，这些有效促进稳定化的带电位点或键轨道的组合对于每种配合物是不同的。
