The Aniline-Water Complex.

The rotational spectra of aniline-water and its 18O isotopomer have been studied in the microwave region between 3 and 26.5 GHz using a pulsed molecular beam FT microwave spectrometer. The spectra were described in terms of a centrifugally distorted asymmetric rotor. Assuming a linear hydrogen NellipsisH-O bond and that the water molecule was located in the symmetry plane of aniline, two structures turned out to be possible. In structure (I) the free water proton is directed toward the aniline ring. In structure (II) the proton is bent away from it. Ab initio calculations indicate that only structure (I) is supported by the experimental results. Copyright 1998 Academic Press.