Blue Acid Chemistry (12): K5[Co2O2Bl10].H2O
Hmm...
To be honest, the whole series of the Co-Bl complexes are very confusing, especially about the colors.
But we have to go advance.
In this complex, the bridge is a superoxo ligand, which contains an O-O 1.5 bond and bears 1 negative charges. Structure is still very similar to (8).
Reference is still the same as (8). Those papers claimed it to be a Co(III,IV) complex with a peroxo ligand which is of course very absurd.
2[Co2O2Bl10]6- + ClO- + H2O = 2[Co2O2Bl10]5- + Cl- + 2OH-
2g(0.036mol) KOH was dissolved into 10mL water to form a strongly basic solution. Then, 1.65g(0.0025mol) K6[Co2O2Bl10].H2O was dissolved into it to form a deeply reddish-brown solution.
3mL bleach(~4% NaClO, ~0.0016mol) was added. Quickly, the solution turned into a nice red.
EtOH was added, initially very carefully with quick stirring to prevent oil formation, then large amount was added. Solution separated into a pink solution and some reddish-brown solid. Filter to collect the solid.
Solid was dried in a vacuum desiccator with CaCl2. It turned into a color that is hard to describe, but different from both K6[Co2O2Bl10].H2O and K3[CoBl6]. Yield: 1.56g(100%).
IDK if the product is contaminated with the peroxo complex, if so then the concentration of bleach is lower than what it claimed. Basic solution is orange and seems to be unaffected by NaClO, which may prove its identity.
According to the paper and Manual, this complex is more stable than the peroxo counterpart. However it might be photosensitive.
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