ELECTRIC DIPOLE MOMENTS OF HC1 - AND HCN-HYDROCARBON COMPLEXES

Abstract

Electric dipole moments of several hydrocarbon-HCN and hydrocarbon-HC1 complexes have been measured using a pulsed-nozzle Fourier-transform microwave spectrometer. The dipole moments ($\mu$) and complexation-induced dipole moments $(\Delta \mu)$ are (in D): [FIGURE] The dipole moments for the HF complexes have been measured $previously^{1,2}$ using molecular beam electric-resonance spectroscopy. The HC1-benzene result is in good agreement with the 1.6(1) D moment determined by Gandhi $et al.^{3}$ using electric deflection techniques. The induced dipole moments show a number of interesting features. With the same acid binding partner, the acetylene and ethylene complexes give similar induced moments while the cyclopropane complexes give the largest induced moments. Except for the benzene complexes, the induced dipole moments increase as: $X-HCN < X-HC1 < X-HF$ and do not follow the dipole moments of the acid binding partners which are ordered: $HC1 < HF < HCN$.