Infrared spectrum and ab initio calculations of the HNH+-Ne open-shell ionic dimer

The IR photodissociation spectrum of the HNH+-Ne open-shell ionic complex h as been recorded in the vicinity of the N-H stretch fundamentals of HNH+ (n u (1) and nu (3)). The rovibrational analysis of the spectrum is consistent with a quasilinear proton-bound HNH+-Ne geometry in the (3)Sigma (-) elect ronic ground state and an intermolecular separation R(H-Ne)similar to1.93 A ngstrom in the ground vibrational state. Ab initio calculations at the UMP2 /aug-cc-pVTZ level confirm that the diradical character and quasilinearity of HNH+ are only a little affected by the weak interaction with Ne. The dis sociation energy of the complex is calculated as D-e=530 cm(-1).