Octanuclear {Co6W2} aggregate versus mixed valence {Co}3 cluster in the assembling of Co(phen)2Cl2 (phen = 1,10-phenanthroline) with octacyano metallates: A case of non-isostructurality between {W(CN)8}4− and {Nb(CN)8}4−

An unprecedented octanuclear aggregate, [{Co(phen)2}6{W(CN)8}2Cl2] · 2Cl, 2, resulted from the assembling of {Co(phen)2Cl2}, 1, and {W(CN)8}4−. Surprisingly, the reaction with the paramagnetic {Nb(CN)8}4− unit did not afford the homologous {Co–Nb} cluster. Instead the latter building unit undergoes dissociation which led to the formation of a mixed-valence [{CoII(phen)2}{CoIII(phen)(CN)4}2], 3. This observation is in contrast to the usual trend that {NbIV(CN)8}4− forms compounds isostructural to that observed for {MoIV(CN)8}4− and {WIV(CN)8}4−. The structures of the compounds 2 and 3 have been established by single crystal X-ray diffraction. Magnetic behaviors for compounds 1–3 are reported.