CONFORMATION AND STABILITY OF ADDUCTS OF CYCLIC AMMINES WITH WATER - FREE JET ABSORPTION MILLIMETER-WAVE SPECTRUM OF PYRROLIDINE-WATER

The free jet millimeter wave absorption spectra of the 1:1 complexes b etween two isotopomers of pyrrolidine (normal and N-D) and four isotop omers of water (H2O, HOD, D2O, and (H2O)-O-18) have been assigned. Alt hough only the rotational spectrum of axial-pyrrolidine has been previ ously reported, the adduct is formed with equatorial-pyrrolidine. The water molecule lies in the plane of symmetry of pyrrolidine; the water hydrogen involved in the hydrogen bond is axial with respect to the r ing, while the ''free'' hydrogen is entgegen to the ring. The three at oms involved in the hydrogen bond adopt a bent arrangement with a N-ri ng... H distance of about 1.89 Angstrom and angle(N-ring... H-O) congr uent to 163 degrees.