Unique Dispersion-Induced Tetrel Bond with Co-operative s-hole-Induced Pnicogen Bond in the POCl3-Acetone Heterodimer: Experimental Confirmation at Low Temperatures

Both tetrel and pnicogen bonds are known to be induced through sigma-/pi-holes. This work reports computational and experimental evidence of the carbonyl carbon of acetone hosting a tetrel bond by dispersion rather electrostatic forces, for the first time, while phosphorus of POCl3 sustains pnicogen bonding via the sigma-hole. Heterodimers of POCl3 with acetone (CH3COCH3) have been isolated within inert gas matrixes of Ar and N-2 at 12 K. Characteristic vibrational bands at P=O stretching of POCl3 and C=O stretching of CH3COCH3 have been obtained in support of the computations. The potential energy surface has been traced computationally using ab initio and density functional methods. CH3COCH3 harboring such a tetrel bond, in itself, is quite intriguing. The interplay of these interactions has been comprehended by the quantum theory of atoms in molecules, natural bond orbital, energy decomposition, electrostatic potential mapping, and noncovalent interaction analyses.

Automated summary

This study reports for the first time the formation of a tetrel bond in acetone through dispersion forces rather than electrostatic forces, while phosphorus in POCl3 sustains pnicogen bonding via the sigma-hole. Computational and experimental evidence supports these findings, which have been comprehended using various analysis methods.