In-Depth Investigation of a Donor–Acceptor Interaction on the Heavy-Group-14@Group-13-Diyls in Transition-Metal Tetrylone Complexes: Structure, Bonding, and Property

Stabilization for tetrylone complexes, which carry ylidone(0) ligands [(CO)5W-X (YCp*)2] (X = Ge, Sn, Pb; Y = B–Tl), has become an active theoretical research because of their promising application. Structure, bonding, and quantum properties of the transition-metal donor–acceptor complexes were theoretically investigated at the level of theory BP86 with several types of basis sets including SVP, TZVPP, and TZ2P+. The optimized structures reveal that all ligands X (YCp*)2 are strongly bonded in tilted modes to the metal fragment W­(CO)5, and Cp* rings are mainly η5-bonded to atom X. DFT-based bonding analysis results in an implication that the stability of W–X bond strength primarily stems from the donation (CO)5W ← X­(YCp*)2 formed by both σ- and π-bondings and the electrostatic interaction ΔE elstat. The W–X bond possesses a considerable polarizability toward atom X, and analysis on its hybridization is either sp2-characteristic or mainly p-characteristic. EDA-NOCV-based results further imply that the ligands XY perform as significant σ-donors but minor π-donors. The visual simulations of NOCV pairs and the deformation densities assemble a comprehensive summary on different components of the chemical bond via σ- and π-types in the complexes. This work contributes to the literature as an in-depth overview on predicted molecular structures and quantum parameters of the complexes [(CO)5W-X­(YCp*)2] (X = Ge, Sn, Pb; Y = B–Tl), conducive to either further theoretical reference or extending experimental research.