Dipole Moments of Furan-Argon and Pyrrole-Argon

Abstract

The dipole moments of furan and furan-argon were determined as 0.685 (2) D and 0.701 (6) D, respectively, from Stark shifts by use of a cavity Fourier transform microwave (FTMW) spectrometer. The larger moment in the complex is in contrast to isoelectronic pyrrole and pyrrole-argon where a decrease was observed from 1.767 (2) to 1.707 (3) D. The changes are attributable to the induced dipole moment in the argon. Ab initio calculations of the electric field at the argon site were used to estimate the induced dipole components for comparison with experiment and agree much better than estimates employing the dipole and quadrupole moments of the heterocycle. © 1990 American Chemical Society.