Fourier transform infrared spectra and normal mode analysis of 1-[(3-methylphenyl)piperazin-1-yl]-3[thio(4-acetamido-phenyl]propane: a potent 5-HT2 and D-2 receptor ligand

1-[(3-methylphenyl)piperazin-1-yl]-3-[thio(4-acetamidophenyl]propane and it s analogs have shown good hypotensive activity and the title compound has s hown a profile of centrally acting anti-hypertensive agent. It also binds w ith the 5-HT2 receptors. The conformation of the title compound was determi ned by X-ray diffraction but this is not possible for its analogs because o f the difficulty in preparing their single crystals. A novel and easy appro ach is envisaged to determine the conformation in such cases by the applica tion of semi-empirical molecular orbital calculations, Fourier transform in fra red (FTIR) spectroscopy and normal mode analysis. As a first step in th is direction the FTIR spectrum of the title compound has been recorded and its normal mode analysis carried out. The assignments of the frequencies ar e based on the concept of group frequencies and band intensities. The spect rally observed frequencies have been tabulated along with the theoretically calculated ones and their assignments. Good agreement has been obtained be tween them and a set of 101 force field constants is established. (C) 2000 Elsevier Science B.V. All rights reserved.