Structural variability of cobalt(II) coordination polymers:: Three polymorphs of Co3(TMA)2 [TAU = trimesate, C6H3(COO)33-]

The aqueous reaction of cobalt(II) sulfate with trimesic acid (H(3)TMA = 1,3,5-benzenetricarboxylic acid) in the presence of a base yields complexes with the general formula Of Co-3(TMA)(2). The identity of the base determines the specific structural characteristics of the complexes formed. When sodium hydroxide is used, a novel cobalt(II) coordination polymer, {[NaCo3(TMA)(2)(mu(3)-OH)](mu(2)-H2O)(4)(H2O)(7).1.5H(2)O}(n) (1), is produced. Compound I contains NaCo3(OH) clusters connected via TMA ligands into 1D chains, and 1 crystallizes in the orthorhombic space group Pbca with a = 18.907(2) Angstrom, b = 14.565(3) Angstrom, c = 21.414(4) Angstrom, and Z = 8. When triethylamine is used, the previously reported 1D zigzag chain coordination polymer, [Co-3(TMA)(2)(H2O)(12)](n) (2), is produced. When tetraethylammonium hydroxide is used, a trinuclear cobalt(II) complex, [Co-3(TMA)(2)(H2O)(14)].4H(2)O (3), is produced that has a structure identical to a segment of the zigzag chain of 2. Compound 3 crystallizes in the triclinic space group P (1) over bar with a = 6.6542(5) Angstrom, b = 10.7114(7) Angstrom, c = 12.3567(7) Angstrom, alpha = 99.008(4)degrees, beta = 102.553(6)degrees, gamma = 107.344(7)degrees, and Z = 1.