Crystal architecture and magnetic properties of four transition-metal adipate coordination polymers
(EN)
Bakalbassis, E. G.
(EN)
Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
(EL)
Bakalbassis, E. G.
(EN)
The crystal structures have been determined and the magnetic properties investigated for four novel [M-II(A)(H2O)(m)](n) polymeric complexes, where M-II=Cd-II, Cu-II or Ni-II, m=2-4 and A=adipate dianion. In [Cd(A)(H2O)(2)](n) 1, [Cu(A)(H2O)(2)](n) 2 and [Ni(A)(H2O)(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. Each cadmium(II) and nickel(II) ion in 1 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)(H2O)(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(1) and Cu(2), which exhibit octahedral and square pyramidal coordination geometries, respectively. Weak antiferromagnetic interactions were observed for 2, and 3 (singlet-triplet energy gap values of -2.3 and -54.5 cm(-1), 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.
(EN)
