Crystal architecture and magnetic properties of four transitionmetal adipate coordination polymers

摘要

The crystal structures have been determined and the magnetic properties investigated for four novel [M~(II)(A)(H_2O)_m]_n polymeric complexes, where M~(II) = Cd~(II), Cu~(II) or Ni~(II), m = 2-4 and A = adipate dianion. In [Cd(A)(H_2O)_2]_n l, [Cu(A)(H_2O)_2]_n 2 and [Ni(A)(H_2O)_4]_n 4 the combination of the metal cation with the dicarboxylate ligand leads to the formation of infinitive chains; still the co-ordinated water molecules and the carboxylate oxygen atoms collaborate to hydrogen-bond the chains into 3-D structures. Eachcadmium(II) and nickel(II) ion in I and 4 is coordinated in an octahedral geometry to carboxylate and water molecules. The coordination sphere around copper(II) ions in 2 is square planar. The structure of 3, [Cu_3(A)_2(OH)_2(H_2O)_4]_n, is made up of ribbons linked to neighboring ones by hydrogen bonds. Each ribbon is composed of 2 crystallographically independent metal centers, Cu(l) and Cu(2), which exhibit octahedral and square pyramidal cooTdination geometries, respectively. Weak antiferromagnetic interactions were observed for 2, and 3 (singlet-triplet energy gap values of -2.3 and -54.5 cm~(-l), respectively) and isolated nickel(II) ions for 4. An interpretation of the magnetic behavior was attempted. The strategy for the assembly of 1-D metal-organic chains into 3-D structures, with the use of coordinated water molecules as hydrogen bond donors and carboxylate oxygens as hydrogen bond acceptors, is also discussed.