Photolysis of methylphosphine in an argon matrix: spectral characterization of methylphosphinidene (CH3P) and phosphaethene (CH2PH).

Vacuum-ultraviolet (VUV) photolysis of methylphosphine (CH3PH2) isolated in a cryogenic argon matrix yields phosphaethene (CH2PH), methylphosphinidene (CH3P), phosphaethyne (HCP), methane, and phosphorus monohydride (PH) as the primary photoproducts. Subsequent irradiation at 254 nm induces the decomposition of CH2PH, accompanied by the formation of CH3P. In contrast, irradiation at 311 nm promotes the decomposition of CH3P and the PH⋯CH4 complex, leading to the regeneration of CH2PH and CH3PH2. These wavelength-selective photochemical transformations made it possible to carry out the first IR and UV spectroscopic characterization of CH3P and to extend the assignment of infrared bands for CH2PH.