Abstract
The reactions of different transition metals with the multidentate ligand N,N′‐bis(1,3,4‐thiadiazol‐2‐yl)‐2,6‐pyridinedicarboxamide (btapca) afford six new polynuclear complexes: the hexanuclear complexes [{Zn~6~(O)~2~(btapca)~4~}·3DMF·2H~2~O] (1) and [{Zn~6~(O)~2~(btapca)~4~}·DMF·MeOH·H~2~O] (2); the pentanuclear complexes [{Zn~5~(OH)~2~(btapca)~4~}·4DMF·H~2~O] (3), [{Co~5~(OH)~2~(btapca)~4~}·4DMF·MeOH·H~2~O] (4) and [{Ni~5~(OH)~2~(btapca)~4~}·4DMF·MeOH] (5); and the trinuclear complex [{Fe~3~(OH)(btapca)~3~}·2DMF·2MeOH] (6). The dominant characteristic of these polynuclear complexes is that there are μ~3~‐ or μ~4~‐oxygen atoms in the metal polyhedrons. The hexanuclear complexes 1 and 2 show similar octahedral features based on zinc centers. The five metal centers in complexes 3, 4 and 5 arrange into two triangles with one common vertex. As for complex 6, three iron(II)/iron(III) atoms form a plane with a μ~3~‐OH^−^ in the center. We also report the magnetic properties of complexes 4, 5 and 6. Complex 4 exhibits intramolecular antiferromagnetic exchange, while the analogous complex 5 is dominated by very strong intramolecular ferromagnetic coupling. The trinuclear complex [{Fe~3~(OH)(btapca)~3~}·2DMF·2MeOH] (6) shows comparable weak antiferromagnetic coupling. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)