Vibrational spectra and conformational isomerism of calixarene building blocks.: Part I.: Diphenylmethane, (C6H5)2CH2

The conformational and normal coordinate analysis of vibrational spectra of the diphenylmethane molecule has been realised within the framework of density functional theory. The calculated force field (B3LYP/6-31G*) was transformed to nonredundant internal coordinates. It is shown that after assignment of two different scaling factors for aromatic and aliphatic C-H coordinates, the scaled quantum mechanical (SQM) method reproduces the complete experimental range of the IR and Raman spectra with high accuracy (mean deviation: 5.5 cm(-1)). The set of nine different scaling factors will be used in conformational studies of calixarene building blocks. (C) 2001 Elsevier Science B.V. All rights reserved.