Hi all. I’m writing up the lab report for my lab on preparation of trans-Bis(ethlenediamine)dinitrocolbat(III)Nitrate, and it’s taken me a while, and I still only understand like half of what’s going on here.
The way I’m understanding it is, first, we mixed Co(NO3)2 hydrate with NaNO2. According to the diagrams in the lab packet, NO2 groups replaced the two of the waters- why they don’t replace all six I have no idea- and then we added en in acid solution. The nitric acid was used to neutralize the en, but we didn’t neutralize it entirely because unneutralized en was the reactant needed, along with NO3-, and neutralized en was just a byproduct.
Then, somehow, atmospheric oxygen oxidizes Cobalt to get [Co(en)2(NO2)2]NO3.
So I have two questions: one, why doesn’t the NO2 group in the beginning replace all six of the waters? Is it just because the two it replaces were in a slightly more unstable location than the other four? (I really don’t understand transition metal complexes so if that’s not a thing it’s because I’m dumb). And, two, what on earth is the oxygen doing to oxidize Cobalt?