Microwave spectra of the 129Xe and 131Xe isotopes of Xe-NO2 have been recorded using a Fourier transform microwave spectrometer. Intermolecular superhyperfine interactions were observed between the Xe nuclear magnetic moment and the unpaired electron on the NO2 radical. These were analysed in terms of a Fermi contact contribution (due to a non-zero electron spin density at the xenon nucleus), a dipole-dipole contribution and an electric quadrupole term (for the 131Xe isotope only). All these terms are a sensitive probe of distortions to electronic wavefunctions due to intermolecular forces.
