Insight into the -hole•••-electrons tetrel bonds between F2ZO (Z=C, Si, Ge) and unsaturated hydrocarbons

The intermolecular -hole-electrons interactions between F(2)ZO (Z=C, Si, Ge) molecules and unsaturated hydrocarbons including acetylene, ethylene, 1,3-butadiene and benzene were constructed to reveal the differences of tetrel bonds forming by carbon and heavier tetrel atoms. The ab initio computation in association with topological analysis of electron density, natural bond orbital, and energy decomposition analysis demonstrate that the strength of Si and Ge tetrel bonds is much stronger than that of C tetrel bonds. The Si and Ge tetrel bonds exhibit covalent or partially covalent interaction nature, while the weak C tetrel bonds display the hallmarks of noncovalent interaction, the electrostatic interaction is the primary influencing factor. The Si and Ge interactions are determined by both the sigma- and -electron densities, while the C interactions are dominated mainly by the -electron densities. The -hole-electrons tetrel bonds are dominated by electrostatic interaction, and polarization has a comparable contribution in the Si and Ge tetrel bonds.