The Unexpected Synthesis of a New (μ2-hydroxo-μ2-peroxo) Dicobalt Complex

The compound, [cis-dichloro-(tris-2-amino(ethylamine))cobalt(III)]chloride hydrate, [cis-Cl2-(tren)Co(III)Cl]·H2O, a conglomerate crystallizing in P21 with Z = 4 (Z’ = 2), has been used as a precursor in the synthesis of a new dicobalt(III) peroxo complex: [(μ2-hydroxo)(μ2-peroxo)bis(tris-2-amino(ethylamine))di-cobalt(III)] tris(triiodide) dihydrate. This material crystallizes, without disorder, in space group P212121 with Z = 4 (Z’ = 2), thus making it, unambiguously, an example of a conglomerate. Its cell constants are 11.1416(2), 16.0553(3), 20.7699(3) A, V = 3715.36(11) A3, measured at 100K, with an R-factor of 3.69% and a Flack parameter of -0.012(7). There are no phase transitions induced by warming the crystals to 296K. It is obtained from an aqueous NH4I solution in two different ways, described below.