Comparison for σ-hole and π-hole tetrel-bonded complexes involving cyanoacetaldehyde

Abstract

ABSTRACTAb initio calculations have been performed for the complexes of cyanoacetaldehyde (CA) with TH3F (T = C, Si, Ge and Sn) and F2TO (T = C and Si). The σ-hole and π-hole tetrel-bonded complexes are formed for TH3F and F2TO, respectively. In general, three minima complexes (N, O–A and O–B) are obtained for each tetrel donor. Most complexes are stabilised by a primary tetrel bond and a secondary hydrogen bonding. TH3F–N/F2CO–N has greater stability than TH3F–O/F2CO–O, but a reverse result is found in the complexes of F2SiO although they have comparative interaction energies. Charge transfer from the lone pair on the N/O atom of CA into the T–F σ* antibonding orbital leads to the stabilisation of the TH3F complexes. Accordingly, the T–F bond is extended and its stretch vibration displays a redshift. A breakdown of the individual forces involved attributes the stability of the complex mainly to electrostatic energy, with relatively large dispersion term in the CH3F complexes and relatively large polarisation energy in the F2SiO complexes.