Sciencemadness Discussion Board

Transitional Metal chemistry project - volunteers?

JustMe - 30-3-2008 at 18:05

Woelen?

So, I'm cleaning out my closet to paint it (because of some minor smoke damage from a condo fire in the next building), and I find my old science project chems - gosh, they've been sitting there for 37 years, the results of my experiments in late high school and early college (when, for a short time, a professor encouraged me because... in his words, I may be onto something "new" - as in a new bond or ligand). That is about as sexy as it got, for this otherwise mundane investigation.

Basically I was trying to find out if the Saccharin anion could act as a bidentate ligand in transitional element compounds.

http://en.wikipedia.org/wiki/Saccharin

I found my samples of Copper I and II, Cobalt II and III, Manganese II, Zinc, Silver, Ferrous, and Paladium II (yes) Saccharin compounds - with all their pretty colors and fine crystals (at the very least, they grew decent sized pretty crystals - the Paladium compound crystallized as cubes!).

If anyone is interested in investigating these, I'd strongly consider shipping these salts to you. Why do I think it is worth it? Because (like Woelen's mystery copper compound) there is some interesting stuff going on when you look deeper. I mean it is obvious that the Copper II, Cobalt II, Ferrous, Manganous and Zinc compounds are hydrated. But it was easy to substitute ammonia, ethylene diamine in the Copper and Nickel compounds. Well, big deal... if it is hydrated, it probably isn't using Saccharin as a ligand. Not necessarily - it may be both.

But to whet someone's interest - when the copper II compound is dissolved in acetone (or MEK), it forms a dark green solution from which dark green crystals come out which I suspect is anhydrous Copper II Saccharin. Same thing happens from DMSO. I often wondered if it had a structure analogous to anhydrous Copper II acetate, which it resembles, and which is a coordinate complex.

Anyway, the basic compounds are easy to make from Sodium Saccharin and a soluble metal salt... they precipitate out from mixing aqueous solutions, but are soluble in hot water, so easily recrystallized. And, if a saturated solution is allowed to evaporate slowly, you can get impressive crystals.

So, am I interesting anyone enough? Here are some of my unresolved challenges from this project. Ferric and Chromic compounds could not be made like the others because the solutions are too acidic and they precipitated free Saccharin. The real challenge was my prediction that Chromous II Saccharin would be a brick red precipitate similar to Chromous II Acetate, but I never could get any Chromium II salts (yes, I know they are exquisitely sensitive to oxygen).

So, I'm trying to decide what to do with these chemicals. Grow pretty crystals? Or find someone interested in picking up where I left off? Based on IR spectra done, it does appear that the hydrated salts only have 2 molecules of hydration, and that the Saccharin is bound to the transitional metal salt as a ligand. This makes for some interesting substitution reactions and COLOR changes.

Maybe there is a paper in this for someone - or maybe someone just likes to play with unusual compounds from common substances which make pretty crystals.

Oh, BTW there were a few, very few other miscellaneous chems in that box... I was interested in plant hormones and had acquired some 3-Indole Acetic Acid and 6-Benzylaminopurine. As I said, over 30 years old (almost 40) and I can't for the life of me figure out why I had some Germanium Tetraiodide. Oh well.

Just chumming the waters to see what happens.

microcosmicus - 30-3-2008 at 18:16

Do you still have notes from when you were doing these
experiments or a write-up from when you were studying
this as an undergraduate? If so, maybe you could post
them here? I would certainly be interested in taking a look.

woelen - 30-3-2008 at 23:24

This indeed sounds quite interesting. I do not have saccharin compounds, but what you write about them sounds interesting. I do have DMSO and other solvents like CH3CN, NH2CH2CH2NH2 which could be interesting to dissolve such compounds.

Maybe I could make a nice write-up on these complexes. If you consider shipping the saccharin compounds, keep in mind that I am in the EU. Some compounds may be troublesome, shipping them overseas. If there are no oxidizers between the compounds, nor any liquids, then the problem probably is not that big, but it is something you should keep in mind.

Swany - 31-3-2008 at 07:54

I would suggest searching literature for saccharin as a chelating agent. When you mentioned it to me a while ago, I did not follow up, however I was searching literature last fall or so and found something mentioning saccharin as a ligand. I don't have journal access at the moment, so I cannot check up on it, but that is a place to start.

JustMe - 31-3-2008 at 11:39

Swany -

OMG, your suggestion brought tears to my eyes when I found:

http://www.scielo.br/scielo.php?pid=S0100-40422005000200025&...

I was more than 35 years ahead of this research, and only lack of money kept me from doing it. :( :(

This small article shows me that the Saccharinate Ion acts EXACTLY as I predicted!

Also:
Quote:

Nevertheless, probably the most interesting dimeric species of this type is the [Cr2(sac)4py2].2py complex31, in which the four saccharinate moieties act as bidentate bridges between the two Cr(II) cations and which therefore resembles the well known Cr(II)/carboxylate species


That was ALSO another prediction of mine, that with Cr (II) it would form a dimeric species, bridging the two Cr (II) cations! Just look above when I predicted that the Chromous compound would resemble Chromous Acetate!

I feel extremely gratified that someone has picked up this research... and also a bit sad that I couldn't have finished it back in 1972. This was originally a high school Science Fair Project and all I got was an honorable mention. And when the money ran out, so did my research as an undergraduate at the university. As the professor said, he could only let me use the facilities while he had extra funds - because it was the Graduate students who were the ones who were funded. So I never published. Such is life.

Anyway, if I can find my bottle of Sodium Saccharin (which may be in my storage bin), I would very interested in a "Woelen write up." If I find that, you could even see about forming possible Ruthenium or Iridium complexes. As you can see from the link, this rather common chemical generates a very interesting chemistry with Transitional elements.

JustMe - 31-3-2008 at 12:19

FOUND IT! Ah, the bottle of Sodium Saccharin (Merck) I bought back in 1969 when a kid could go to a Chemical Supply Company and buy almost anything (I'm not kidding, I bought Chloroform, Sulfuric Acid... yep, if I wanted to, I could have bought Acetic Anhydride - but those days are long gone). But they didn't carry Chromous Sulfate or Chloride. Anyway this would provide plenty of raw starting material. The 1 ounce bottle is at least half full.

Anyway Woelen - if you're serious about playing around with this interesting ligand and the colorful compounds it forms with Transitional Metals (and maybe hear some of my suggestions of things that I think would be impressive)... U2U me. I have NO IDEA how to ship this kind of stuff to Europe.

These are not oxidizers, but simple salts in jars very similar to those which you have your chems in (from your website). Perfectly safe (well, I wouldn't eat them even if they did taste sweet, LOL), no liquids.

microcosmicus:

I looked and couldn't find my notes anywhere - long since thrown away. Sigh. But now that I see someone has taken up this research it is not as important for me that someone pick it up from me. Thank you, thank you for asking!

woelen - 31-3-2008 at 13:30

See your U2U box, I'm sure we can arrange something :). Thanks for this offer, I will enjoy this kind of chemistry!

[Edited on 31-3-08 by woelen]

JohnWW - 31-3-2008 at 13:42

It is not clear whether the "sodium saccharin" in this thread is some sort of sodium salt of the artificial sweetener with the proprietary name of Saccharin, which is 3,500 times sweeter than sucrose but has no structural resemblance to carbohydrate saccharides, being instead a secondary amine, sulfone, and ketone, with hexavalent S bonded to a benzene ring and a N atom in a 5-membered ring; or whether it is the sodium salt of saccharic acid, better known as glucaric acid, a polyalcoholic dicarboxylic acid, HOOC-(CHOH)4-COOH, obtained by the partial oxidation of (+)-glucose with HNO3. Which is it? Saccharin (which has been banned as a sweetener in Canada but not the USA) could form an amine salt with an acid, but there does not seem to be any easy way that it could form an anion by ordinary reaction with a simple base like NaOH, unless the N-S bond in the 5-membered ring is cleaved to form a sulfonic acid anion.

[Edited on 1-4-08 by JohnWW]

microcosmicus - 31-3-2008 at 13:51

According to the links provided in the posts above, it is clearly the
former. In particular, the article mentioned by Swamy, to which a
link is provided in the next post, states that the anion is formed
by simply losing the H connected to the N, not forming a sulfonic anion.

JohnWW - 31-3-2008 at 14:01

Yes, come to think of it, that could happen by way of a tautomeric shift of the secondary amine H atom, to one of the two sulfone oxygen atoms to form the -OH of what would be a quite acidic azasulfonic acid group, with the N-S bond becoming a double N=S bond.