Gas-Phase Pyrolysis of Tervalent Phosphorus-Oxy and -Thia Heterocycles: A new Approach to Short-Lived Pentavalent Phosphorus Compounds Having Co-Ordination Number 3

Generation of short-lived metaphosphonates by thermal fragmentation of cyclic phosphonites and their thia-analogues in the gas phase is described, including an elaboration of the method whereby a monomeric phosphonobenzene is detected unambiguously for the first time by an intra-molecular trapping reaction which also illustrates the considerable potential of such species in the synthesis of phosphorus heterocycles.