Thread by @ConradGoodwin

So you want to do ammonia-free Birch reductions?

“Large Scale Synthesis of Dysprosium and Neodymium Diiodides” (plus Thulium 💚).

pubs.acs.org/doi/abs/10.102…

A thread #ChemTwitter #RealTimeChem (but from the past). (Table - pubs.acs.org/doi/10.1021/ja…)

https://twitter.com/stephenaboydph1/status/1291973419760627712

Divalent lanthanide chemistry is often limited to Sm(II), Eu(II) and Yb(II). Eu(II) is actually stable in degassed water, the other two are oxidized. SmI2 is a powerful reductant used lots in organic chemistry.

Eu(II) has some pretty #Fluorescence!!

Now, Sm, Eu and Yb behave nicely and you can just take the metal carefully with I2 in THF to make [LnI2(THF)5], which can be partially desolvated. In that picture above the inner blue is [EuI2(THF)5], and the outer pale blue is EuI2(THF)2.

You can also use I-C2H4-I, or I2CH2.

Moving to Tm(II), with reduction potential of -2.3V vs NHE it starts getting unhappy in organic solvents.

You *can* make [TmI2(DME)3] from Tm(0) + TmI3 in boiling DME (onlinelibrary.wiley.com/doi/10.1002/an…) but it’s also temperature and light sensitive. It’s tough to get the timing right.

If you want Dy(II) and Nd(II) iodides, the -2.5V and -2.6V vs NHE is too much for organic solvents. Ethereal solutions degrade quickly, and they can only be made in the solid-state from Ln(0) and I2 (…mistry-europe.onlinelibrary.wiley.com/doi/abs/10.100…)

Both of these Ln(II) diiodides can be carefully crystallized from THF/DME and their structures are known (onlinelibrary.wiley.com/doi/10.1002/15… / pubs.acs.org/doi/full/10.10…)

In a really cool demonstration, the Evans group showed that DyI2 can even reduce naphthalene, producing DyI3 as a byproduct I expect.

This is ammonia-free Birch reduction.

The Ln(0) + I2 reaction is powerfully exothermic, and can quite easily cause glass Schlenk vessels to violently shatter.

An alternative is to use a quartz reactor system where you conduct the synthesis in molten LnI2 that you carefully produce at first.

Under static vacuum in the Bunny Reactor, you first heat up some clean, freshly prepared Ln metal, for example Tm. We filed it manually in the glovebox.

The metal and iodide are loaded into the two bunny ears which are rotated to tip reagents down the quartz delivery tubes.

Once the metal is hot you’re ready to add the first, tiniest splash of I2. This video is a classic favorite of @millsgroupchem, featuring Hannah being super excited.

Here is where the Tm metal ignites when the I2 contacts it. We have a vast excess of Tm(0) at this point.

Once completed, we crank up the temperature > melting point of the LnI2, ensuring reaction is conducted in the melt and that you get reasonable transport of fresh metal to prevent oxidation to TmI3 which had a much higher melting point.

Making sure to “top up” the vacuum often.

Once hot enough you sequentially add Ln(0) and I2, always ensuring you have an excess of Ln(0).

Each I2 addition is pretty damn cool, heating the molten LnI2 up to a bright yellow glow.

Once everything is added, it’s cooled down under dynamic vacuum to remove excess I2.

Once at room temperature the whole kit is transferred to a glovebox antechamber and pumped in.

Open it up and can tip out the LnI2 nugget, which is manually separated from some white LnIO impurities from the quartz.

Grind it up. I think the green solution here was from NdI2.