Vibrational spectrum of buspirone

Article abstract of DOI:10.1016/S0022-2860(96)09384-2

The IR and Raman spectra of buspirone and buspirone hydrochloride were recorded in KBr pellets and chloroform solutions. Most of the vibrational bands were assigned to normal modes using quantum mechanical semiempirical and ab initio restricted Hartree-Fock (RHF) calculations on model systems. The essential spectral characteristics can be obtained from the analysis of three building blocks of buspirone, i.e. pyrimidine-piperazine, butyl spacer and imide residues. The spectral regions particularly sensitive to intermolecular interactions were identified. The theoretical calculations suggest that the 'NH⁺' band in buspirone hydrochloride reflects the formation of a moderately strong hydrogen bond between the protonated piperazine nitrogen atom (bound to the butyl spacer) and the chlorine anion.