Sciencemadness Discussion Board

Remarkable chemistry of S, Se and Te

woelen - 29-7-2007 at 11:41

I read about some really unknown chemical properties of S, Se and Te. These elements can form cations, like many metals, but these cations are not simple ions like S(n+), but polycations.

I succeeded in making Te4(2+) and Se8(2+), but not any sulphur cations. Nevertheless, the result is quite stunning and is something which I want to share.

http://woelen.homescience.net/science/chem/exps/SSeTe_H2SO4/...

For making the very special cationic species, only concentrated sulphuric acid is needed, and of course the elements. The elements Se and Te can be obtained from eBay from element sellers.

EDIT(woelen): Changed link, such that it works again.

[Edited on 28-5-13 by woelen]

Nerro - 29-7-2007 at 12:02

"Woelen, playing with Te so that you don't have to!" ;)

If you're interested in cationic homoatomic molecules you might also be interested in Wade clusters of Pb and other similar elements. (Sn also I believe).

JohnWW - 29-7-2007 at 13:37

What salts are these cluster cations of Se and Te present as? Do they exist in solution, or have you isolated crystalline salts? (And hopefully determined their molecular weights by such means as depression of the freezing point of solutions or mass spectrometry, and examined their structure by such means as X-ray diffraction). Did you find evidence of Se-Se and Te-Te stretching frequencies in their IR spectra?

You say you have made Se8(2+) (is it cyclic?) but not the cation of sulfur. Yellow sulfur consists of cyclic neutral S8 molecules, and red Se consists of cyclic neutral Se8 molecules, however. I wonder if mixed S-Se and S-Te cluster cations could be made.

[Edited on 30-7-07 by JohnWW]

JustMe - 29-7-2007 at 17:49

Ditto Nerro's comment... very interesting stuff.

I have a somewhat off topic question on the chemistry of Sulfur (I've always been fascinated with the progression of chemistry in Group VI elements - including the relatively recent discoveries of O4 and the isolation of S2 solid) but I'm not up to date on the very latest. What I mean is that I regularly search for stuff on "impossible" compounds (as of 30, 20 and 10 years ago) that have been created. The classic case being perbromate, which is now even available commercially. I'm also fascinated by fluorine chemistry... but back to where I was going.

Iodides of oxygen, selenium and tellurium exist (although the first one are Iodine Oxides), but, as of my old books, none of Sulfur. I've read that mixures of Sulfur and Iodine do not react. Okay, does anyone know if any genuine binary compounds of Sufur and Iodine exist? How they were prepared? And what are their properties? Any trinary compounds (salts)? If they still have not been synthesized, why are they said to not exist?

Sorry to "hijack" with this question... I'm just curious to fill this "hole" in Group VI/Group VII chemistry that I've known since the 1970's. A lot has happened since then! (Waiting for N60!)

woelen - 30-7-2007 at 10:23

Quote:
Originally posted by JohnWW
What salts are these cluster cations of Se and Te present as? Do they exist in solution, or have you isolated crystalline salts? (And hopefully determined their molecular weights by such means as depression of the freezing point of solutions or mass spectrometry, and examined their structure by such means as X-ray diffraction). Did you find evidence of Se-Se and Te-Te stretching frequencies in their IR spectra?

You say you have made Se8(2+) (is it cyclic?) but not the cation of sulfur. Yellow sulfur consists of cyclic neutral S8 molecules, and red Se consists of cyclic neutral Se8 molecules, however. I wonder if mixed S-Se and S-Te cluster cations could be made.

I wish I could do all the things you mention in your post. Remember, this is home chemistry, not in a fully equipped uni-lab, or company-lab. The information I have is from literature (Chemistry of the elements, Earnshaw and Greenwood). After reading those things, I decided to try this at home. Unfortunately, this kind of modern chemistry books almost never give reaction conditions, they only menion the existence of all kinds of compounds, and give lots of structural information. No recipes or procedures for making such 'strange' compounds. I also have some information from older books, which describe special phenomena, but do not give an explanation (I had the red/purple Te-reaction conditions from an old pre-1950 book). I myself decided to try this with Se and S, and indeed it succeeds with Se.

The structure of the Se8(2+) ion is not simply cyclic. In my webpage, I give the 3D structure of this ion, according to two sources (the book mentioned above, and a journal: Inorganic Chemistry, by the American Chemical Society, volume 25, number 21, october 8, 1986).

In the concentrated sulphuric acid, I only can imagine the salt [Se8]SO4 and [Te4]SO4. Or, when bisulfate is formed: [Se8][HSO4]2 and [Te8][HSO4]2. Isolating such compounds from concentrated sulphuric acid, however, is not something for a home chemist.

@Justme: No problem with your 'hijack' of this thread ;). I have looked up my chemistry book and it mentions the existence of a few pure sulphur/iodine compounds. In 1974, an Indian research group has isolated S2I2, which was made by reacting S2Cl2 with HI in freon solvent at -78 C, with some I2 added as catalyst. This compound is unstable and quickly decomposes, when stored above -30 C.
One other true sulphur/iodine compound was synthesized in 1976. This is the ion [S7I](+), with a 7-membered sulphur ring, with an iodine atom attached to one of the atoms in the ring. This ion is deep orange, and it was synthesized by direct reaction of iodine and sulphur in SbF5 solvent (which is oxidizing). With extra fluoride added, a salt can be isolated, [S7I][SbF6]. This ion, and the very unstable S2I2 are the only known S/I compounds.
There also is another compound, SCl7I, but this is not a true sulphur-iodine compound, because it is a salt [SCl3][ICl4], and the iodine is in the yellow ICl4(-) ion.

DerAlte - 5-8-2007 at 12:40

Wonderful stuff, Woelen! Has anyone else any good and easily obtained references on these ionic exotics?

Regards,

Der Alte

JustMe - 6-8-2007 at 09:31

Wow, thanks. I've always suspected that S2I2 could exist, and expected it to be like SCl4, very unstable to temperature and that is how it turned out. Appreciate you updating me in this area. I've never lost my love for chemistry even though my life went in an entirely different direction.

S7I+? Extreme and very cool chemistry.

turd - 6-8-2007 at 11:08

Nice. One minor comment:
Quote:
The white solid SO3ยท2TeO2 is immediately hydrolyzed by water.

Of course you can see it like that but I wouldn't write it this way. The SO4-tetrahedra do not share oxygens like in SO3. What you really have is (Te2O3)SO4.

The structures of the Te[IV] salts with acids are basically the same as the ones with bases. They mostly are Te/O-networks consisting of the classic [TeO3], [TeO4] and [TeO3+1]-polyhedra with a huge lone-pair sticking out at one end and anions resp. cations in between. The salts with bases are less condensed than TeO2, the salts with acids on the other hand are more condensed.

The sulfate is quite interesting. Two of the SO4-oxygens are around 2.2A away from the Te, giving TeO3+1-polyhedra. Apparently the nitrate is not known.

What makes me wonder though is why the sulfate is so easily hydrolysed. The chloride Te6O11Cl2 is easy to make and is very stable in acidic solution, even at high temperatures.

More structural information:

Te2O3(SO4)
Monatshefte fuer Chemie (1976), 107, 721-730
Acta Crystallographica B (1976), 32, 2720-2722
Acta Crystallographica B (1976), 32, 3115-3116
J.Chem.Soc. Dalton Transactions (2000), 2000, 4542-4549

Te6 O11 Cl2
Zeitschrift fuer Naturforschung B (1981), 36, 405-409
Acta Crystallographica C (1994), 50, 3-4

Te6 O11 Br2
Bulletin de la Societe Chimique de France (1977), 1977, 251-253

nitroglycol - 6-8-2007 at 12:30

Anyone want to try dibutyl telluride?
Quote:
From the point of view of the hetero-atom itself, there are two more known below selenium in the Periodic Table. Each deserves some special comment. The next atom, directly below selenium, is tellurium. It is more metallic, and its com-pounds have a worse smell yet. I heard a story about a German chemist, many years ago, who was carrying a vial of dibutyl telluride in his pocket in a passenger coach from here to there in Germany, back at about the turn of the century. It fell to the floor and broke. No one could remain in the car, and no amount of decontamination could effectively make the smell tolerable. Scratch one railway coach. But the compound, 2C-TE, would be readily makeable. Dimethyl ditelluride is a known thing.

Source.

woelen - 14-8-2007 at 14:04

Quote:
Originally posted by turd
Of course you can see it like that but I wouldn't write it this way. The SO4-tetrahedra do not share oxygens like in SO3. What you really have is (Te2O3)SO4.

[...]

More structural information:

Te2O3(SO4)
Monatshefte fuer Chemie (1976), 107, 721-730
Acta Crystallographica B (1976), 32, 2720-2722
Acta Crystallographica B (1976), 32, 3115-3116
J.Chem.Soc. Dalton Transactions (2000), 2000, 4542-4549

I updated my webpage. It now contains a link to your (this!) post I quote, credits go to you for this information ;)

woelen - 29-4-2008 at 11:48

I now have some 20% oleum and did the experiment with sulphur again. Now I could make the beautiful deep blue species S8(2+). I modified the webpage with this set of experiments:

http://woelen.homescience.net/science/chem/exps/SSeTe_H2SO4/...


I also did the experiment with iodine and I could also make iodine cationic species, such as the nice blue I2(+) cation and probably some higher species as well. A write-up about that follows in a separate page and more reading is necessary for me to understand all the things I see.

This chemistry of cationic species in oleum is really remarkable. The selenium and tellurium experiments also are different, but before I can make a write-up on these, I need a much better understanding of what happens here. With tellurium I get an amazingly deep red liquid, it really looks like blood. When kept in contact with air it is dark red/brown and it gives off strong fumes and eats through thick paper and fabric in seconds. Nice stuff for a cheap class B horror movie :P

EDIT(woelen): Changed link so that it works again.


[Edited on 28-5-13 by woelen]

Jor - 29-4-2008 at 12:33

AWESOME!
Great stuff Wilco!!!
Quite dangerous stuff is oleum as far as I know :O

DJF90 - 29-4-2008 at 14:22

Woelen, quick note. Under "selenium in hot sulphuric acid" you have written "The piece of tellurium has a thickness of..." Just thought I would let you know :)

woelen - 2-5-2008 at 10:49

DJF90, thanks for telling me about the error. I changed it :).