Substituent constants (σp−) of the rotated nitro group : the interplay between the substituent effect of a rotated −NO2 group and H-bonds affecting π-electron delocalization in 4-nitrophenol and 4-Nitrophenolate complexes : a B3LYP/6-311+G** study - Dobrowolski, Michal A. (Array, 2009)