Polynuclear cobalt(II/III) sulfites:: Synthesis, structure, and magnetic properties of the octanuclear cluster (NH4)11(Li⊂[Co4IICo4III(SO3)16(NH3)8])•10H2O encapsulating a lithium cation

Partial oxidation of an aqueous solution of (CoCl2)-Cl-II center dot 6H(2)O with (NH4)(6)[(Mo7O24)-O-VI]center dot 4H(2)O in the presence of (NH4)(2)SO3 center dot H2O and LiCl, at pH approximate to 5.3, leads to isolation of the octanuclear cluster (NH4)(11)(Li subset of[(Co4Co4III)-Co-II(SO3)(16)(NH3)(8)]center dot 10H(2)O), 1. The structure of the anion of 1 consists of a central [CO4II], almost ideal square planar unit, and a pair of symmetry-related Co-III dimers above and below the Co-4(II) plane grafting onto the tetramer by 16 bridging sulfite groups. The [Co-8(SO3)(16)(NH3)(8)](12-) cluster encapsulates a lithium cation which lies at the center of the Co4(II) square.