Methoxyphosphinidene and Isomeric Methylphosphinidene Oxide.

A rare oxyphosphinidene (Me-OP) has been generated in the triplet ground state through either photolysis (266 nm) or flash-vacuum pyrolysis (FVP, 700 °C) of methoxydiazidophosphine MeOP(N). Upon ArF laser irradiation (193 nm), an unprecedented isomerization from Me-OP to the long-sought methylphosphinidene oxide (Me-PO) occurs in cryogenic Ne- and N-matrices. Alternatively, the latter can be efficiently generated through photolysis (193 nm) or FVP (ca. 700 °C) of methylphosphoryl diazide MeP(O)(N), in which the elusive nitrene intermediate MeP(O)(N)N in the triplet ground state has been also observed by IR (with N-labeling) and EPR (| D/ hc| = 1.545 cm and | E/ hc| = 0.003 95 cm) spectroscopy.