Add to ORKGAuthor Institution: Department of Chemistry, University of Connecticut; Department of Chemistry, University of MichiganThe $^{14}N$ species has been assigned and the $^{14}N$ quadrupole coupling analyzed. The 15N species has also been assigned and its dipole moment determined. The Ar atom is located 3.56 A from the pyrrole center of mass and the Ar-center of mass line is tilted $5.8^{\circ}$ from the normal to the pyrrole plane toward the N atom. The dipole moment of the complex, $1.7074(11) D$, is smaller than that of pyrrole. $1.7675(6) D$. From a pseudodiatomic centrifugal distortion analysis, the binding energy is $261(2) cm^{-1}$