ELECTROSTATIC INTERACTION ENERGIES FROM DIPOLE-MOMENTS IN NITRILES, AMMONIA AND AMINES - CORRELATIONS WITH HYDROGEN-BOND BASICITY

Experimental molecular dipole moments and related bond and mesomeric m oments were used to calculate the energy W-A of the electrostatic: att raction between N-containing acceptor molecules and the attracted H at om, the hydrogen bond N ... H being along the symmetry axis of N, A sa tisfactory but family-dependent linear relationship is obtained betwee n W-A and the hydrogen-bond basicity scale pK(HB) in 36 nitriles, ammo nia and 11 primary and tertiary amines. The energy W-R of the electros tatic repulsion between the acceptor molecule and the moment of the cr eated N<--H bond is calculated in a similar way, W-R is strongly famil y dependent but the total energy W-A+W-R is closely correlated with pK (HB)in the 48 derivatives studied without a significant Family depende nce, This analysis clarifies and completes a previous similar study an d confirms that dipolmetry and classical electrostatic calculations ca n be a useful and practicable method for the prediction of the strengt h of hydrogen bonding. (C) 1997 by John Wiley & Sons, Ltd.