Infrared studies of matrix-isolated and neat solid nitrosyl chloride

Abstract

The infrared spectra of nitrosyl chloride (ONCl) isolated in rare gas solids have been studied in an attempt to verify the existence of a dimer. The results indicate that with increased concentration and with high-temperature annealing one or more types of dimers or possibly trimers form in argon and krypton matrices. In a xenon matrix the authors see the presence of dimers at concentrations of 0.2%, and eventually multimers and aggregates form with high-temperature annealing. In liquid solutions of ONCl in krypton, xenon, and carbon disulfide no evidence of dimer formation is seen. In the solid state at 150-160 K they see absorption peaks at 1,925 and 520 cm{sup {minus}1}, which are attributable to the molecular solid showing Raman peaks at 1,900 and 475 cm{sup {minus}1}. For the ionic phase they observe an infrared NO{sup +} stretching frequency of about 2,090 cm{sup {minus}1}, close to that observed in Raman spectra. The frequency of the NO stretch for the molecular solid is strongly influenced in an upward direction by the presence of intimately dispersed ionic solid, leading them to believe that the molecular solid consists of long chains with strong intermolecular coupling rather than discrete dimers.