Polynuclear Cobalt(II/III) Sulfites: Synthesis, Structure, and Magnetic Properties of the Octanuclear Cluster (NH₄)₁₁(Li⊂[Co₄^IICo₄^III(SO₃)₁₆(NH₃)₈])·10H₂O Encapsulating a Lithium

Partial oxidation of an aqueous solution of CoIICl2·6H2O with (NH4)6[Mo7VIO24]·4H2O in the presence of (NH4)2SO3·H2O and LiCl, at pH ≈ 5.3, leads to isolation of the octanuclear cluster (NH4)11(Li⊂[Co4IICo4III(SO3)16(NH3)8]·10H2O), 1. The structure of the anion of 1 consists of a central [Co4II], almost ideal square planar unit, and a pair of symmetry-related CoIII dimers above and below the Co4II plane grafting onto the tetramer by 16 bridging sulfite groups. The [Co8(SO3)16(NH3)8]12− cluster encapsulates a lithium cation which lies at the center of the Co4II square.