CRYSTAL AND MOLECULAR-STRUCTURE OF PYRYLIUM-SALTS .2. CRYSTAL AND MOLECULAR-STRUCTURE OF 2,6-DIPHENYL-4-(4-NITROPHENYL)PYRYLIUM PERCHLORATE NITROMETHANE SOLVATE, ELECTRONEGATIVITY EFFECT ON GEOMETRY OF THE CATION

The crystal and molecular structure of 2,6-diphenyl-4-(4-nitrophenyl)pyrylium perchlorate nitromethane solvate was solved with R = 0.067 for 2827 reflections and mean esd for bond lengths 0.005 angstrom and bond angles 0.4-degrees. Phenyl rings attached to positions 2, 4 and 6 of the pyrylium ring exhibit a strong deformation of angular geometry indicating enhanced electronegativity of carbon atoms 2, 4 and 6 due to the positive charge on them. Exocyclic valence angles at carbon atoms 2 and 6 of the pyrylium ring are strongly deformed from 120-degrees due to the strongly electronegative oxygen atom with partial positive charge, STO-3G, 3-21G and 6-31G* ab initio calculations support this interpretation.