Can metal halides be electron donors in σ-hole and π-hole tetrel bonds? Cooperativity with an alkaline-earth bond

The tetrel bond in the complexes of TH3F-MX2 (T = C-Sn, M = Be and Mg; X = F, Cl, and Br) and F2CO-MX2 has been explored and it is also called carbon bond for T = C. The results show that the halogen atom of metal halide can engage in a sigma-hole interaction with TH3F and a pi-hole interaction with F2CO. A linear carbon-bonded complex is formed between CH3F and MX2, while a cyclic structure is obtained in other complexes, where a tetrel bond coexists with an alkaline-earth bond. The carbon bond between CH3F and MX2 is weak with interaction energy less than 9 kJ/mol, depending on the nature of M and X atoms. The alkaline-earth bond is stronger than the tetrel bond in the cyclic complexes and both interactions display positive cooperativity. The F2CO-MX2 complex is more stable than TH3F-MX2, mainly due to the stronger alkaline-earth bond in the former. The pi-hole carbon bond is also stronger than the sigma-hole carbon bond when a metal halide acts as an electron donor. Such tetrel-bonded structures involving metal halides have been found in the Cambridge Structural Database.

Automated summary

The carbon bond interactions in complexes involving metal halides have been explored, showing that the halogen atom of metal halide can engage in either σ-hole interaction with TH3F or π-hole interaction with F2CO, resulting in different carbon bond structures.