The effect of including polarization functions on the geometrical parameters calculated for pyridine

Geometrical parameters for pyridine have been calculated using the 6-31G, 6-31G^*(5D), 6-31G^**(6D), and 6-31G(2 × 6D) basis sets. Comparisons are made with a microwave substitution structure and with results of other ab initio calculations reported in the literature. Particular attention is paid to the influence of polarization functions on the magnitude of the ring angle, 〈C₆N₁C₂, which is analogous to the ipso angle in monosubstituted benzene derivatives.