Fluorine bridging in the xenon fluoride cations and their salts: The base strengths of XeF2, XeF4 and XeF6

It is a feature of the structures of all the salts of XeF+, XeF3+ and XeF5+ that have been studied, that the cation forms one or more fluorine bridges to the anion. The length, direction and number of the fluorine bridges in these salts throw new light on the relative fluoride ion donor abilities of the xenon fluorides XeF2, XeF4 and XeF6. In constrast to what has previously been supposed, it is concluded that the order of fluoride ion donor ability is XeF2 < XeF4 < XeF6.