The size of the metal ion controls the structures of the coordination polymers of benzo-2,1,3-selenadiazole

The products of the combination of benzo-2,1,3-selenenadiazole with chloride salts of divalent Mn, Fe, Co, Ni, and Cd crystallize from DMSO in two distinct structural types. While the smaller ions form infinite chains of metal atoms N,N′-bridged by the heterocycle, the larger ions stabilize infinite chains of metal atoms bridged by μ2 halide ions. In the latter case, two heterocycle molecules cap each metal ion and are able to establish a link to the next chain in the lattice through the [Se–N]2 supramolecular synthon. Despite the large (>9.2 A) distance between the [M(μ-Cl)2]∞ chains, the manganese derivative is only paramagnetic.