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kmno4
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Registered: 1-6-2005
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| Quote: | Originally posted by 12AX7
(...)
I don't think steric hinderance would matter much; although O(2-) ions are quite large, even the quite small Si(4+) and S(6+) are extremely
comfortable surrounded by them. But your point was that O(6+) should be even smaller, in fact quite a bit smaller than the isoelectronic helium due
to the extra charge. In that case, (O)O3 or even just (O)O2 might be the most that can fit. The latter does exist, i.e. ozone, but not with a 4+
charged center.
Tim |
Firstly - there are no any ions in such covalent bounded particles as H2SO4, HNO3, SiO2, HClO4.... etc. You must not compare O(-2) ion with covalent
oxygen.
I used to count distances between oxygens in orthonitrate anion NO4(-3), from crystallographic data (articles from Wiley).
It turn out that this distance is "critical", almost equal to Van der Waals's radius for oxygen. So, similar structures: OO4(2-) and FO4(-) should be
far less stable than NO4(3-), because of smaller radius of central atom. This steric hinderance can be very important reason of nonexistence of
H2OO4.
Of course, not the only one.
[Edited on 19-7-2008 by kmno4]
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