Electron impact fragmentation of some mixed cyclotetraphosphazenes

The electron impact fragmentations of some cyclotetraphosphazenes are reported and discussed. The major fragmentation path involves loss of two amine radicals and one chlorine radical in the series P₄N₄Cl_8-n(NMe₂)_n when n=2, and subsequent stages involve a ring contraction process with elimination of a P = N fragment, when n = 5 loss of amine radicals predominates on statistical grounds with little evidence of ring contraction. In the series P₄N₄F_8-n(NMe₂)_n fragmentation is dominated by loss of amino radicals when n = 4 and loss of fluorine radicals predominates on statistical grounds when n = 2. In the series P₄N₄F_8-nX_n (n = 2 or 4, X = Cl or Br), when n = 2 and X = Br the major fragmentation path is the loss of two bromine radicals, whereas when X = Cl the more favoured path is the loss of two chlorine radicals. In both, subsequent stages involve ring contraction reactions with elimination of a PN fragment. When n = 4 and X = Br or Cl on bond energy grounds the more favoured fragmentation pattern is the loss of bromine or chlorine radicals, respectively.