Hydrogen‐Bonded Complexes of HPN⋅ and HNP⋅ Radicals with Carbon Monoxide

Abstract

Listen

Translate article

AbstractPhosphorus mononitride (PN) is a carrier of phosphorus in the interstellar medium. As the simplest derivatives of PN, the radical species HPN⋅ and HNP⋅ have remained elusive. Herein, we report the generation, characterization, and photochemistry of HPN⋅ and HNP⋅ in N2‐matrix at 3 K. Specifically, HPN⋅ was formed as a weakly bonded complex with CO in the matrix by 254 nm photolysis of the novel phosphinyl radical HPNCO⋅. The ⋅NPH−CO complex is extremely unstable, as it undergoes spontaneous isomerization to the lower‐energy isomer ⋅PNH−CO through fast quantum mechanical tunneling (QMT) with a half‐life of 6.1 min at 3 K. Upon further irradiation at 254 nm, the reverse conversion of ⋅PNH−CO to ⋅NPH−CO along with dehydrogenation to yield PN was observed. The characterization ⋅NPH−CO and ⋅PNH−CO with matrix‐isolation IR spectroscopy is supported by D, 15N, and 13C isotope labeling and quantum chemical calculations at the XYGJ‐OS/AVTZ level of theory, and the mechanism by hydrogen atom tunneling is consistent with multidimensional instanton theory calculations.