This paper deals with quantum chemical explanation of high ionization potential and low electron affinity of WF6 as compared other species of this family. Calculated structure and vibrational frequencies of WF6 by B3LYP, B3PW91 and MP2 schemes are compared with experimental values which establish superiority of B3PW91 over B3LYP and MP2 in the present case. Anionic and cationic forms of WF6 are optimized and analysed at B3PW91 level. It is revealed that low electron affinity of WF6 is due to extra electron localization on W which goes to antibonding molecular orbital. It is also shown that highest occupied molecular orbital is delocalized over F atoms and it is not easy to extract electron from electronegative F which results in very high ionization potential of WF6.
