On the structures of the methanol trimer and their cooperative effects

A previously non-described trimer with a C–H ⋯ O hydrogen bond has been characterized as minimum at several computational levels. This conformer allows a complete assignment of the experimental infrared cavity ringdown laser absorption spectrum (IR-CRLAS) in the O–H stretch region. B3LYP/6-311++G(d,p) charge densities of the methanol dimer and trimers analyzed with the atoms in molecules (AIM) theory indicate the hydrogens of the methyl group play a significant role on the stabilization of these clusters. On the contrary, their cooperative effects can be numerically reduced to those exhibited by the OH groups.