octave
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Hydrates
Hello all!
Recently I've been reading a great deal on the various theories of coordination chemistry, and have been baffled by one thing which is hydrates.
Take for example copper sulfate pentahydrate contains copper in its 2+ oxidation state and therefore can have 4 water molecules coordinately bonded to
it. However as aforementioned it is a pentahydrate.
Research on this has led me to water of crystallization on wikipedia, but I want a better explanation for how exactly this happens. Also I would like
to know why this doesn't happen with other ligands. Thanks!
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chemrox
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I haven't looked up the specific compound you're asking about but in general what you're talking about has to do with point group symmetry and
orbitals. If you're math inclined a good starting place is Cotton & Wilkenson, "Chemical Applications of Group Theory." Happy reading.
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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JohnWW
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To find links for that ebook, search on Google with this search string:
"Chemical Applications of Group Theory" PDF OR DJVU OR ZIP OR RAR rapidshare OR mihd OR megaupload OR esnips
There are several collections of (inorganic) chemistry ebooks in which it is included.
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12AX7
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As I recall, a lot of the 5- and 7-hydrate sulfates are [M.4H2O].[SO4.H2O] or likewise [M.6H2O] (omitting charges on the ions), that is, 4 or 6 waters
per metal ion and one for the sulfate.
Some are inclusion or clathrate sorts of compounds, like I might've heard Na2SO4 hydrate is -- that would make sense given the extravagant amount of
H2O's it has.
Predicting these things in general is a complex combination of coordination chemistry, some of which is not fully understood; electrostatic (ionic,
dipole and dispersion) binding, and fitting weird shapes together (we're not dealing with fat round Na+ Cl- anymore). Throw in some energy and
entropy and you've got one big melting pot (perhaps literally, depending on how you crystallize things  ) of a "very interesting" physical chemistry problem.
Tim
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