In 1962, Neil Bartlett had shown that platinum hexafluoride, PtF6, is a powerful enough oxidiser to remove an electron from molecular oxygen, forming O2+PtF6−; noting that xenon's first ionisation enthalpy (1170 kJ/mol) is very close to that of O2 (1175 kJ/mol), he reasoned that PtF6 should be able to oxidise xenon as well, and on carrying out the reaction he obtained the first noble-gas compound, Xe+PtF6−. Xenon, the most reactive noble gas because of its comparatively low ionisation enthalpy and large, polarisable electron cloud, combines directly with fluorine under different conditions of temperature, pressure and reactant ratio to give three fluorides: Xe+F2→XeF2 (excess xenon, about 673 K), Xe+2F2→XeF4 (1:5 Xe:F2 ratio, about 673 K and 7 atm), and Xe+3F2→XeF6 (1:20 ratio, high pressure, or alternatively from XeF4 reacting with O2F2). Controlled hydrolysis of these fluorides gives xenon's oxygen compounds: complete hydrolysis of XeF6 gives XeO3, XeF6+3H2O→XeO3+6HF, while partial hydrolysis gives the oxyfluorides, XeF6+H2O→XeOF4+2HF and XeF6+2H2O→XeO2F2+4HF; despite involving water, these are simple ligand-exchange (substitution) reactions rather than redox reacti …