CAN THE NONLINEARITY OF HYDROGEN-BONDS B...HX BE MEASURED PRECISELY - A METHOD FROM ROTATIONAL SPECTROSCOPY AND ITS APPLICATION TO 2,5-DIHYDROFURAN...HCL

Rotational constants, centrifugal distortion constants and the complete Cl-nuclear quadrupole coupling tensor referring to the principal inertial axis system have been determined for the ground state of 2,5-dihydrofuran...HCl from its rotational spectrum. The complex has C(s) symmetry, with the hydrogen bond completing a pyramidal arrangement at the oxygen atom of 2,5-dihydrofuran. The coupling tensor allows a good approximation to the equilibrium angle alpha(az) between the HCl(z) axis and the a axis, and thence the nonlinearity theta = 9.5-degrees of the hydrogen bond, to be determined. The results are rationalised in terms of a refinement of a simple model of the hydrogen bond.