hodges - 16-8-2009 at 17:07
When I first saw this on E-Bay
25g Iodine Pentoxide (Crystal) High Purity
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=25043...
I thought it was some kind of joke. But apparently the compound does exist, at least according to Wikipedia.
I wonder if chlorine pentoxide exists as well? It might not be stable because electronegativity difference not as large between chlorine and oxygen
as between iodine and oxygen?
Anyway, this just struck me as a really weird and esoteric compound, so I thought I would post it here. My apologies if it is really nothing out of
the ordinary.
Hodges
JohnWW - 16-8-2009 at 18:08
I(VII) oxo and fluoro-compounds are more stable than those of I(V), which tend to disproportionate; IF7 is the preferred product of direct combination
of the elements with an excess of F2. Also, the (VII) oxidation state of Cl, as Cl2O7, ClO4- and ClF6+ (ClO3+, ClO3F, and ClOF5 may also exist), is
the most stable of the positive oxidation states of Cl.
[Edited on 17-8-09 by JohnWW]
garage chemist - 16-8-2009 at 19:41
Iodine Pentoxide is the anhydride of iodic acid and is made by heating anhydrous HIO3 (also a crystalline substance!) to 250°C, where it gives off
water. Decomposition into iodine and oxygen starts at 300°C. It gives iodic acid again when contacting water.
HIO3 can be made by oxidising iodine with fuming HNO3. There is a procedure for this in Brauer (see library), and for I2O5 too.
Iodine heptoxide (I2O7) is also obtainable (orange polymeric solid, decomposes at 100°C into I2O5) from HIO4 (again crystalline) and conc. H2SO4.
Again, refer to Brauer.
Chlorine heptoxide exists (explosive liquid, made from anhydrous HClO4 and P2O5), but not chlorine pentoxide.
Formatik - 16-8-2009 at 20:16
There is also ClO4 (colorless compd.), Cl2O4 (pale greenish liq.), and Cl2O6 (deep-red, nearly black liquid), and some lower chlorine oxides, but
never seen a Cl2O5. It may exist as an intermediate, but it hasn't been isolated or characterized.
[Edited on 17-8-2009 by Formatik]