Multiconfiguration SCF electric field gradients in (NO)2 and its singly charged ions

Electric field gradients (EFGs) at the N and O nuclei in the complexes (NO)2+, (NO)2 and (NO)2- have been calculated by using the complete-active-space self-consistent field (CASSCF) method with correlation-consistent basis sets. The energetics obtained at given level of accuracy were found to be consistent with previous experimental and theoretical findings. Changes in the EFGs at the nuclei due to the formation of the complex from diatomic species were used to interpret the character of bonding in the triad of dimers. Direct comparison with (molecular beam electric resonance) spectroscopic data was made for NO and its dimer: 14N nuclear quadrupole coupling constants and the electric dipole moment of (NO)2 appeared to be in reasonable accord.