The substituent effects on the biphenyl H⋯H bonding interactions subjected to torsion

Abstract

QTAIM and the stress tensor describe a torsion φ, 0.0°≤φ<25.0°, of the C4-C7 torsional bond that affects the H⋯H bonding interactions linking the two phenyl rings of para-substituted biphenyl, C12H9X, X=N(CH3)2, NH2, CH3, CHO, CN, NO2 and C12H9-Y, Y=SiH3, ZnCl, COOCH3, SO2NH2, SO2OH, COCl, CB3. For all values of X and Y, shorter H⋯H bond-path lengths corresponded to higher values of both the stiffness and torsion φ. The onset of a phase transition-like behavior is found by the stress tensor stiffness. The atomic basins of the H⋯H interactions are affected by the para-substituent groups.