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

Abstract

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: 5.5cm−1). The set of nine different scaling factors will be used in conformational studies of calixarene building blocks.