Editing Hypervalent molecule (section)

==Criticism==
Both the term and concept of hypervalency still fall under criticism. In 1984, in response to this general controversy, [[Paul von Ragué Schleyer]] proposed the replacement of 'hypervalency' with use of the term '''hypercoordination''' because this term does not imply any mode of chemical bonding and the question could thus be avoided altogether.<ref name=Jensen/>

The concept itself has been criticized by [[Ronald Gillespie]] who, based on an analysis of electron localization functions, wrote in 2002 that "as there is no fundamental difference between the bonds in hypervalent and non-hypervalent (Lewis octet) molecules there is no reason to continue to use the term hypervalent."<ref>{{cite journal | doi = 10.1016/S0010-8545(02)00102-9 | title = The octet rule and hypervalence: Two misunderstood concepts | year = 2002 | last1 = Gillespie | first1 = R | journal = Coordination Chemistry Reviews | volume = 233–234 | pages = 53–62 }}</ref>

For hypercoordinated molecules with [[electronegative]] ligands such as PF<sub>5</sub>, it has been demonstrated that the ligands can pull away enough electron density from the central atom so that its net content is again 8 electrons or fewer. Consistent with this alternative view is the finding that hypercoordinated molecules based on fluorine ligands, for example PF<sub>5</sub> do not have [[hydride]] counterparts, e.g. [[phosphorane]] (PH<sub>5</sub>) which is unknown.

The ionic model holds up well in [[thermochemistry|thermochemical]] calculations. It predicts favorable [[exothermic]] formation of {{chem|PF|4|+|F|−}} from [[phosphorus trifluoride]] PF<sub>3</sub> and [[fluorine]] F<sub>2</sub> whereas a similar reaction forming {{chem|PH|4|+|H|−}} is not favorable.<ref>''Predicting the Stability of Hypervalent Molecules '' Mitchell, Tracy A.; Finocchio, Debbie; Kua, Jeremy. J. Chem. Educ. '''2007''', 84, 629. [http://jchemed.chem.wisc.edu/Journal/Issues/2007/Apr/abs629.html Link]</ref>