Solid State Coordination Chemistry of Pyridinedicarboxylic Acid Isomers. I Copper( II ) Disodium Bis(pyridine-2,3- dicarboxylate) Octahydrate and Copper( II ) Pyridine-3,4-dicarboxylate 3·5 Hydrate

The crystal structures of Na2Cu(2,3-pydc)2.8H2O (1) and Cu(3,4-pydc).3·5H2O (2) (pydc = pyridinedi- carboxylato) are presented. Compound (1) is monoclinic, space group C 2/ c , with a 21·274(1), b 6 ·114(1), c 17·136(1) Å, ß 101·62(1)°, Z 4, D c 1·776 g cm-3 ; compound (2) is also monoclinic, space group P 21/ c , with a 7·272(2), b 11·319(3), c 25·453(9) Å, ß 90·58(1)°, Z 4, D c 1·850 g cm-3 . Their stereochemistries are analysed, and compared with other copper(II) pyridine-2,6-dicarboxylates. Ligand constraints are shown to determine the crystal structures and the magnetic properties. Thermal dependence of magnetic susceptibility data and t.g., d.t.g. and d.t.a. measurements are also presented.