Hydrogen-Bonded Complex of the Parent Phosphinidene

The diatomic molecule PH is very reactive, and it serves as the parent compound for phosphinidenes featuring a monovalent phosphorus atom. Herein, we report the characterization and reactivity of a rare hydrogen-bonded complex of PH. Specifically, the molecular complex between PH and HCl has been generated by photolysis of chlorophosphine (H2PCl) at 254 nm in a solid Ar-matrix at 10 K. The IR spectrum of the complex HP & sdot;& sdot;& sdot;HCl and quantum chemical calculations at the UCCSD(T)-F12a/haTZ level consistently prove that the phosphorus atom acts as a hydrogen bond acceptor with a binding energy (D0) of -0.6 kcal mol-1. In line with the observed absorption at 341 nm for the binary complex, the triplet phosphinidene PH undergoes prototype H-Cl bond insertion by reformation of H2PCl upon photoexcitation at 365 nm. However, this hydrogen-bonded complex is unstable in the presence of N2 and HCl, as both molecules prefers stronger interactions with HCl than PH in the observed complexes HP & sdot;& sdot;& sdot;HCl & sdot;& sdot;& sdot;N2 and HP & sdot;& sdot;& sdot;2HCl. A pre-reactive complex (HP & sdot;& sdot;& sdot;HCl) in prototype phosphinidene insertion reactions has been observed in the photoreaction between the parent phosphinidene PH and HCl in an Ar-matrix at 10 K. This hydrogen-bonded complex is highly unstable, as its structure varies in the presence of other weak hydrogen-bond acceptors such as N2 and HCl. image