Isolated Magnetic Clusters of Co(II) and Ni(II) within 3-Dimensional Organic Frameworks of 6-Mercaptonicotinic Acid:  Unique Structural Topologies Based on Selectivity for Hard and Soft Coordination Environments

Hydrothermal reaction of the mixed thiolate−carboxylate−aromatic amine ligand, 6-mercaptonicotinic acid (6-mnaH<sub>2</sub>) with Co(II) and Ni(II) leads to two network coordination solids [M<sub>9</sub>(6-mna)<sub>8</sub>(μ<sub>3</sub>-O)<sub>2</sub>(OH<sub>3</sub>)<sub>2</sub>(OH<sub>2</sub>)<sub>6</sub>] (M = Co, Ni), <b>1</b>, and [M<sub>2</sub>Ni<sub>12</sub>(6-mna)<sub>12</sub>(μ<sub>3</sub>-OH)<sub>2</sub>(OH<sub>2</sub>)<sub>6</sub>]·8H<sub>2</sub>O (M = K, Rb, Cs), <b>2</b>. These compounds are unusual for two reasons:  they are thiolate-bridged networks and they are three-dimensional lattices which contain isolated metal clusters and chains. The magnetic behavior of these compounds has been studied, showing that <b>2</b> contains ferromagnetically coupled Ni<sub>6</sub> wheels.