Weak C–H· · ·O and C–H· · ·p hydrogen bonds in crystal 1-indanone. An structural and spectroscopic analysis

The structure of 1-indanone has been studied by X-ray crystallography, vibrational analysis and theoretical calculations. The crystal structure (determined at 120 K) is stabilised by an extensive network of weak hydrogen bonds of the C–H· · ·O and C–H· · ·p type. The molecular structure has been optimised in the frame of the isolated molecule approximation using ab initio RHF and DFT/B3LYP and BLYP methods with an assortment of basis sets, i.e. 6-31G(d), 6-31G(d,p), 6-31þþG(2d,p), 6-311G(2d,p) and 6-311þþG(2d,p). This allows to compare the theoretical molecular structure and that obtained through X-ray diffraction in such a way that conclusions about the magnitude of the intermolecular interactions can follow. Furthermore, a proposal of assignment of the vibrational spectrum is given since the only early studies available so far are nonconclusive and incomplete. This proposal is assessed by a molecular force field which has been performed according to the SQM methodology starting from the theoretical B3LYP/6-31G(d) and BLYP/6-31G(d) force fields and using a set of experimental IR and Raman spectra. q 2004 Elsevier B.V. All rights reserved