Blue Acid Chemistry (13): K3[V(NO)Bl5].2H2O(FAILED)

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In this complex, the vanadium can be considered as +1, +3 or +5. No matter what the real oxidation state is, we can just consider it as +5 which is the same as NH4VO3, and the reaction is then non-redox.

This complex was originally formulated as K5[V(NO)Bl5].H2O which is considered as a V(-I) complex, but this was found to be due to impurity.

By the way, another complex [V(NO)Bl6]4- is said to exist, but it requires H2S to make which is obviously very impossible(and disgusting) for us.

[VO4]3- + NH2OH + 5Bl- + H2O = [VBl5NO]3- + 5OH-

Ref1 Ref2

The stoichiometry is weird in the paper, but I decided to follow it, just reduce the amount.

1.66g(0.014mol) NH4VO3, 5g KOH and 5g KBl was added to 50mL water to form a colorless solution(ammonia released). Then, 2.66g [NH3OH]Cl was added, solution immediately turn yellow and gradually turned deeper.

It was heated on a steam bath for 2h. Ammonia was released during this, and it seems to be not only dissolved ammonia as the rate is way too high and does not cease in a short time. Three reasons can be given: 1) ammonia is released from the side reaction of low-valent vanadium complexes formation 2) this is in fact a complex redox reaction and the given formula is wrong 3) it is just the disproportionation of NH2OH. Some insoluble stuff was also generated during this. Water was added if needed. It was found that overheating causes decomposition, as the dried solution on the wall becomes brown.

In the end evolution of ammonia ceased and the solution is a dark orange. Ethanol was added carefully but it becomes either sticky amorphous solid or oil no matter how slowly we added. Not a big deal as this state can be used to remove KBl and KCl, just pour the upper ethanol layer away.

After reprecipitating for 3 times, no white precipitation was observed, and the oil was dissolved in minimal water and dried in a box in a dark place. This solution is still extremely basic which may indicate that KBl or KOH is still in it.

Uh... I ran out of my patience and the decomposition seems to be too fast, so... I directly heated it on a steam bath until crystals cover the whole surface. During this the dried solution on the wall gradually became red, which indicates decomposition, probably due to the absence of KBl and KOH, or just dehydration. Since it still can't dry we added ethanol, thinking existing crystals may induce crystallization, only resulted in a sticky shit.

Then we dissolved it again and directly heated it. Strong heating caused serious decomposition but some product remained.

I collected it, all, with all my heart, and decided not to try again. Enough. Yeah, maybe, just like my life, this is deemed to be a huge failure, meaningless, painful, hard, and nobody gives a fuck, but it's all I have, and there is only one. And, it's really interesting, right?

Bonus

We tried again. We used methyl tert-butyl ether(MTBE) to deal with the oil but nothing happened and MTBE did not even diffuse into the solution or oil.

Treating oil with EtOH and stir with a plastic dropper seemed to work, but tiny red crystals generated disappeared on the next day, probably decomposed, as brown crystalline stuff was observed on the wall.

Using K3[FeBl6] to induce crystallization failed and the crystal structures must be very different despite similar stoichiometry.

Natural evaporation resulted in the decomposition of the product into white precipitation which might be KVO3. It was at first assumed to be KBl or KCl but these are way too soluble.

By the way, there is a phenomenon called "the more diluted, the more hydrolyzed" in Chinese textbooks, and this counter-intuitive conclusion can in fact be drawn from simple ideal calculations. However here it is in fact not related.

The papers said that this product is very hard to purify, and something like K4[VBl7] or KBl is very hard to remove.

By the way, MTBE is extremely environmental harmful and we had some time finding out how to dispose it. We finally found that carefully burning it is the best way. Burn a few drops every time. Addition of much ethanol can make the burning process smooth and you can burn much more at a time.

Addition of CaCl2 immediately generated off-white precipitation(A) and color of the solution did not change. Addition of ethanol to the solution immediately generated brown precipitation(B) and solution became colorless. In my opinion, A is calcium vanadate/calcium hydroxide, and B is Ca3[V(NO)Bl5]2.xH2O. This gives us some clues about future experiments. However, while A is slightly soluble in water to form a slightly basic solution, B is insoluble in water which means some unknown decomposition took place.

And this is me, a boy who was abandoned by the whole world, but I finally found my own life, that doesn't need anyone to comment, and I feel so happy. At least I have not let down my non-existent motherland, nor myself.