thebean - 6-12-2013 at 08:13
After reading a post about metalloids as anions, I saw that there are alkali metal anions. For example sodides/natrides, potassides/kalides. I can't
find anything that goes into detail on synthesis of any of these but I've found some interesting articles. This goes into interesting detail about "inverse sodium hydride" where they have H+ ions and Na- ions. If anyone has experience with these
compounds I like to here about your synthesis route and the properties of the compound.
DraconicAcid - 6-12-2013 at 09:18
I've never worked with them, but they are extremely reactive reducing agents. You have to choose your solvents and counterions with care.
kristofvagyok - 6-12-2013 at 14:06
They are extremely unstable. I have made Na+Na-, K+K- and Li+Li-. The potasside and sodide has a really characteristic blue color, when I made the
lithide(?) I haven't observed any color change, just that the lithium granulates got shiny and the reaction what I planned happened.
I would highly recommend this really inspiring article from crown ethers written by Charles J. Pedersen. On the first page he mentions a few article where they describe the blue
coloration when potassium was boiled with polyethers. This could be a good starting point for your research.
I made these alkalides by adding alkali metals to dilute crown ether solutions in abs. tetrahydrofuran at room temperatures. Since the potasside and
the sodide is really reactive, on room temperature they only exist near to the surface of the metal, because they react with the THF forming
KOCH2CH2CH2CH2K.
They work as superbases and could be easily used for organic chemistry, I personally used them instead of BuLi and most of them worked well. If you
have any questions about these, feel free to ask.
Tetrakis - 6-12-2013 at 22:15
In my lab, a coworker is trying to synthesize an anionic chromium arene complex via progressive reduction. Coordinating ions have caused serious
problems in his chemistry, and I was wondering if there might be a way to quantify the amount of reducing reagent you talk about. I suggested he use
an electride, but their isolation (seemed, from a brief literature survey) to require low temperature precipitation from ammonia and an expensive
cryptand. Clearly the ammonia makes this route unacceptable and low temperature evaporation of ammonia is problematic as well.
What kind of success did you have working with these alkalides/electrides? Were you able to quantify the losses, and if so what kind of yields did you
get with respect to the alkali?