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 Co II Cl 2 .6H 2 O with (NH 4 ) 6 [Mo 7 VI O 24 ].4H 2 O in the presence of (NH 4 ) 2 SO 3 .H 2 O and LiCI, at pH ≈ 5.3, leads to isolation of the octanuclear cluster (NH 4 ) 11 (Lic[Co 4 II Co 4 III (SO 3 ) 16 (NH 3 ) 8 ]·10H 2 O), 1. The structure of the anion of 1 consists of a central [Co 4 II ], 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 (SO 3 ) 16 )(NH 3 ) 8 ] 12- cluster encapsulates a lithium cation which lies at the center of the Co 4 II square.