Nature of metal–bis(β-diketonate) bonds in TM(acac’)2 (acac’ = acetylacetonate, hexafluoroacetylacetonate, hexamethylacetylacetonate; TM = Ni(II), Pd(II), Pt(II)) complexes: A density functional theory investigation

Abstract

This computational study investigates the structural and bonding aspects of transition metal bis(β-diketonate) complexes, TM(acac’)2 (acac’ = acetylacetonate, hexafluoroacetylacetonate, hexamethylacetylacetonate; TM = Ni(II), Pd(II), Pt(II)), at BP86/def2-TZVP and M06/def2-TZVP levels of theory. Patterns observed in both computed interaction and stabilisation energies demonstrate an increasing in the order of hexafluoroacetylacetonate < hexamethylacetylacetonate < acetylacetonate. A comprehensive energy decomposition analysis (EDA) was performed to thoroughly examine the attributes of the bonds between the metal and ligands within complexes. According to the EDA results, it is evident that electrostatic interactions exert a greater influence on shaping the overall attractive interactions compared to orbital interactions. However, the significance of the b1g orbitals cannot be overstated, as they contribute more than 41% across all complexes. Additionally, the backdonation processes TM→Lσ and TM→Lπ exhibit notable weaknesses.