Metal–Ligand Bonds in Rare Earth Metal–Biphenyl Complexes

Abstract

A series of theoretical methods, including density functional theory, multiconfiguration molecular orbital theory, and ab initio valence bond theory, are devoted to understanding the metal–ligand bonds in M–BP (BP = biphenyl; M = Sc, Y, or La) complexes. Different from most transition metal–BP complexes, the most stable metal–biphenyl conformers are not half-sandwich but clamshell. Energy decomposition analysis results reveal that the M–BP bonds in the clamshell conformers possess extra-large orbital relaxation. According to the wave function analysis, 2-fold donations and 2-fold back-donations exist in the clamshell M–BP bonds. The back-donations from M to BP are quite strong, while donations from BP to M are quite weak. Our work improves our understanding of the metal–ligand bonds, which can be considered as the “reversed” Dewar–Chatt–Duncanson model.

Synergistic Charge Transfer Effect in Ferrous Heme–CO Bonding within Cytochrome P450

“…Beyond its indisputable role in advancing our comprehension of chemistry after the establishment of quantum mechanics [14], VB theory has undergone significant development in recent decades, becoming a quantitatively competitive ab initio tool [15][16][17]. As it has evolved, ab initio VB theory has extended its application beyond organic molecules, providing invaluable insights into donor-acceptor and metal-ligand interactions [18][19][20][21][22][23][24][25]. Furthermore, VB calculations have brought to light a novel phenomenon termed charge-shift bonding, significantly enriching our comprehension of chemical bonds [26,27].…”

Inverse Bonding – Backbonding: Metal to Ligand σ and Ligand to Metal π Dative Interactions between Bismuth and Boron

“…Since shared covalent bonds are usually stronger compared to dative ones, πX bonding will probably appear exclusively in σX ligands. Usually, (but not always [4] ) σ bonds are stronger than π bonds, and therefore if πX would occur on σZ or σL ligands, they would rotate to form a σX bond and a dative bond to the π system. σZ BH 3 See the above discussion about ammines and phosphines, and compare with AlH 3 below.…”

“…There are several types of bonding styles in metal complexes, some of them even novel and quite stimulating, [1][2][3][4][5][6][7][8] but probably the most studied one is the traditional bondingbackbonding pattern (BBB, also known as donation-backdonation, or the Dewar-Chatt-Duncanson model when dealing with alkenes). In this, the ligand donates an electron pair to an empty d orbital on the metal forming a σ bond, while in parallel a π bond is formed by donation from an occupied d AO on M to an empty MO on L (usually a π*).…”