Why would fluorine have a positive oxidation state in #"HOF"# even though it is more electronegative?
2 Answers
It is due to the oxidation numbers of hydrogen & oxygen.
Explanation:
Hydrogen has a
Oxygen generally has a
But, fluorine is a more electronegative element than that of oxygen.
Hence, the oxidation state of oxygen must be higher than that of fluorine in positive sense.
But in order to make the charge of the entire molecule
Hope it Helps:)
DISCLAIMER: CONTROVERSIAL!
As it turns out, the coordinates of
#" "" "color(white)(...)x (Å)" "" "" "y(Å)" "" "color(white)(.)z(Å)#
#"O"" "color(white)(..)0.0529" "" "color(white)(.)0.7143" "color(white)(..)0.0000#
#"H"" "-0.8995" "color(white)(.....)0.8346" "color(white)(..)0.0000#
#"F"" "color(white)(..)0.0529" "color(white)(.)-0.7277" "color(white)(..)0.0000#
And since the dipole moment of
#vecmu = << mu_x, mu_y, mu_z >> = << 2.200, 0.370, 0 >># ,
an electron density map would then indicate that oxygen is slightly more negative than fluorine in this compound, while both oxygen and fluorine are significantly more negative than hydrogen.
So in that regard, apparently, an oxidation state of
It makes no sense on electronegativity grounds, i.e. this is one case where blindly following IUPAC rules trumps electronegativity.
The oxidation state of fluorine in
Then, treating this as an acid (as anyone should!),
#"HOF"(aq) rightleftharpoons "H"^(+)(aq) + "OF"^(-)(aq)# ,
and one would see that to practice conservation of charge AND electronegativity for
#"F"# has a#-1# oxidation state.#"O"# has a#0# oxidation state.
On the other hand, since
#"O"# has a#-2# oxidation state.#"Cl"# has a#+1# oxidation state.
However, the fluorine oxidation state of
In the end, oxidation states are just an accounting scheme. They may or may not mean anything physical. Relying on electronegativity especially falls apart for the fluorine oxoacids, and one cannot rely on oxidation state assignments, using electronegativities as a guide, as indicative of true partial charges.
[In fact, there are no partial charges according to oxidation state schemes! That falls on dipole moment analysis!]