Both perfluoroalkyl sulfur pentafluorides and the tetrafluorides have demonstrated the tendency to form what appear to be fluorocarbon free radicals when they are heated up to their respective decomposition temperatures. The pentafluorides also appear to produce F* radicals. In all cases thus far examined, SF4 is the other main product. For e~ ample,~-~ RrSF4Rf and RfSF6, where Ri is CFB, CiFg and C4F9, have been shown to form R r R f ...