Double-bond elucidation for arsagermene with a tricoordinate germanium center: a theoretical survey

Abstract

Multiple-bonded heteronuclear combinations have recently received great attention because of the first experimental arsagermene (>GeAs–) synthesis, which is a relevant topic in organometallic chemistry. However, a systematic elucidation of the GeAs bond still remains necessary. Here, we report a computational investigation, based on second order Moller–Plesset perturbation theory and density functional theory calculations, of arsagermene with a tricoordinate germanium center, to understand the >GeAs– double bond and the influence of the substituents on the stabilization process. We considered a diversified set of R₂GeAsR compounds to understand the nature and magnitude of the arsagermene bond. Geometrically we have obtained an excellent agreement with experimental results, where the GeAs bond is confirmed to be a double bond, with a theoretical underestimation of 0.05 Å in the bond length. After a complete characterization of the substituents, we obtain that they influence the GeAs formation, mainly through a push-and-pull effect, which comes mainly from the R groups bonded to the Ge species. From the studied topological parameters, a large strength is obtained for the GeAs bond with electron density accumulation, considering electronegative R groups (e.g., halogens), as well as lone pair groups (hydroxy, methoxy, and amine groups). Finally, from the energy decomposition analysis, we obtained a type of interaction-model and the nature of the GeAs bond for all compounds, especially for (H₃Si)₂GeAsPh, which is our model of the synthesized arsagermene compound. The >GeAs– bond was characterized with 52.86% orbital contribution, 44.19% electrostatic interaction, and 2.95% dispersive contribution. The other compounds followed the same trend, helping to complete the picture for the double-bond elucidation for arsagermene.