Relevance of Dispersion Interactions in the Germylidyne and Stannylidyne Complexes of Manganese: Structure and Bonding‐Energy Analysis

Abstract

AbstractDensity functional theory (DFT) and dispersion‐corrected DFT calculations were used to study the nature of Mn≡E bonds in the cationic manganese‐ylidyne complexes trans‐[H(dmpe)2Mn≡E(Mes)]+ (E = Ge, Sn) and [H(dmpe)2Mn≡Sn(C6H3‐2,6‐Mes2)]+ by using BP86, PBE, and PW91 functionals. The calculated geometrical parameters of the stannylidyne complexes are in good agreement with the available experimental values. Significant non‐covalent interactions appear between the metal fragment and the ligands in the studied complexes, which were determined by the QTAIM‐defined topological analysis. The electronic structure of the Mn≡E bonds was examined by Voronoi deformation density (VDD) charges and Nalewazskii–Mrozek bond orders. The overall electronic charge transfers from [E(Mes)] or [E(C6H3‐2,6‐Mes2)] to [H(dmpe)2Mn] fragment. The energy decomposition analysis shows that the Mn≡Ge bond has more covalent character than ionic, and the percentage of ionic character increases from Ge to Sn. The bond dissociation energy at the DFT/BP86 level for the Mn≡Ge bond (67.6 kcal/mol) is larger than that of the Mn≡Sn bond (55.8 kcal/mol). The D3(BJ) dispersion interactions between metal fragment and EMes ligands add nearly 17.0 kcal/mol to the Mn≡E bond dissociation energies. The dispersion energy contribution increases with the bulkiness of the ligand substituent. The distortion of the Mn–E–C bond angle has been discussed in terms of a Jahn–Teller distortion.