Synthesis, crystal structures, and magnetic properties of two three-dimensional octacyanotungstate(IV)-based bimetallic frameworks with 4,4'-bipyridine dioxide (4,4'-dpdo)

The reaction of [HN(n-C4H9)(3)](3)[W-V (CN)(8)]center dot 4H(2)O, 4,4'-bipyridine dioxide(4,4'-dpdo), and MnCl2 center dot 4H(2)O or CuCl2 center dot 2H(2)O gives two new three-dimensional octacyanometalate-based bimetallic assemblies, {[Mn-2 (4,4'-dpdo)(H2O)(4)] [W-IV (CN)(8)]{center dot 6H(2)O (1) and {[Cu-2(4,4'-dpdo)(H2O)][W(CN)(8)]{center dot CH3OH center dot H2O (2). Compound 1 crystallizes in the orthorhombic system, space group P2(1)2(1)2 with cell constants alpha=10.397(2) A..., b=11.321(2) A..., c=12.295(3) A... and Z=2, whereas 2 crystallizes in the monoclinic system, space group P2(1)/c with cell constants a=13.038(3) A..., b=13.784(3) A..., c=13.225(3) A..., beta=93.44(3)A degrees and Z=4. In complex 1, each [W-IV (CN)(8)](4-) unit with a square antiprismatic geometry is connected to four Mn-2 dimers through four bridging CN- ions forming wavelike alternating-W-Mn-2-W-Mn2- layers, which are further linked through 4,4'-dpdo ligands coordinated to the Mn ions into a three-dimensional open framework. In complex 2, each [W-IV (CN)(8)](4-) ion still adopts a square antiprismatic geometry, whereas it bonds to seven copper ions through seven CN- ions leading to cage-like undulate layers further bridged by 4,4'-dpdo ligands into a three-dimensional network. Due to the bridging role of the long rigid 4,4'-dpdo ligand, there exist plenty of large cavities in the open frameworks of complexes 1 and 2 occupied by solvent clusters containing H2O or CH3OH molecules. To our knowledge, it is noted that 4,4'-dpdo displays a mu-4,4,4',4' mode, which was first experimentally observed, although predicted before. Magnetic studies show that complex 1 displays an antiferromagnetic coupling between Mn-II ions, while complex 2 exhibits a weak ferromagnetic interaction between Cu-II ions.