A fluoroaryl substituent with spectator function: Reactivity and structures of cyclic and acyclic HF4C6-substituted phosphanes

The reactivity of a series of phosphanes with a fluoroaryl group (HF4C6-) carrying a spectator function in para position has been explored with respect to the formation of low coordinated and phosphorus rich phosphanes. An asymmetric diphosphene has been indentified as an intermediate in the synthesis of a linear 1,3-dihydrophosphane, while the symmetric diphosphene undergoes 2 + 2 cycloaddition under formation of the corresponding cyclotetraphosphetane for which a crystal structure could be obtained. Attempts to synthesize HF4C6-substituted iminophosphanes generally failed, which is attributed to the electronic nature of the corresponding precursors as suggested by quantum chemical calculations.