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

The conformational and normal coordinate analysis of vibrational spectra of the diphenylmethane molecule has been realised within the framework of den sity functional theory. The calculated force field (B3LYP/6-31G*) was trans formed to nonredundant internal coordinates. It is shown that after assignm ent of two different scaling factors for aromatic and aliphatic C-H coordin ates, the scaled quantum mechanical (SQM) method reproduces the complete ex perimental range of the IR and Raman spectra with high accuracy (mean devia tion: 5.5 cm(-1)). The set of nine different scaling factors will be used i n conformational studies of calixarene building blocks. (C) 2001 Elsevier S cience B.V. All rights reserved.