Competition between σ-hole pnicogen bond and π-hole tetrel bond in complexes of CF<sub>2</sub>=CFZH<sub>2</sub> (Z = P, As, and Sb)

<p>A computational study of the complexes formed by F<sub>2</sub>C=CFZH<sub>2</sub> (Z = P, As, and Sb) and F<sub>2</sub>C=CFPF<sub>2</sub> with two Lewis bases (NH<sub>3</sub> and NMe<sub>3</sub>) has been carried out. In general, two minima complexes are found, one with a σ-hole pnicogen bond and the other one with a π-hole tetrel bond in most complexes but two σ-hole pnicogen bonded complexes are obtained for F<sub>2</sub>C=CFZH<sub>2</sub> and NH<sub>3</sub>. They have similar stability though F<sub>2</sub>C=CFSbH<sub>2</sub> engages in a much stronger σ-hole pnicogen bond with NMe<sub>3</sub>. The –PF<sub>2</sub> substitution makes the π-hole on the terminal carbon form a tetrel bond with NH<sub>3</sub>. A heavier –ZH<sub>2</sub> group engages in a stronger σ-hole pnicogen bond but results in a weaker π-hole tetrel bond. Other than electrostatic interaction, the stability of both complexes is attributed to the charge transfer from the N lone pair into the C–Z/H–Z anti-bonding orbital in the pnicogen bond and the C=C anti-bonding orbital in the tetrel bond.</p> <p>The σ-hole pnicogen bonded and π-hole tetrel bonded complexes between F<sub>2</sub>C=CFZH<sub>2</sub> (Z = P, As, and Sb) and two Lewis bases (NH<sub>3</sub> and NMe<sub>3</sub>) have been compared. The results indicate that both interactions can compete, dependent on the nature of the N base.</p>