Structure and magnetic properties of two cyanide-bridged one-dimensional M-CuII (M = FeIII or FeII) bimetallic assemblies from ferricyanide and CuN42+ (N4 = 1,4,8,11-tetraazacyclotetradecane and N,N′-bis(2-pyridylmethylene)-1,3-propanediamine) building blocks

Two bimetallic assemblies K[Cu(cyclam)][Fe(CN)(6)]. 4H(2)O 1 and [Cu(L)][Cu(L-1)][Fe(CN)(6)]. 6.5H(2)O 2 (cyclam = 1,4,8,11-tetraazacyclotetradecane; L = N,N'-bis(2-pyridylmethylene)-1,3-propanediamine and L-1 = N-2-pyridylmethylene-1,3-propanediamine) have been prepared from the reaction of [Fe(CN)(6)](3-) and the precursors [Cu(cyclam)](2+) and [Cu(L)](2+), respectively, and their structure and magnetic properties studied. The structure of 1 consists of polymeric zigzag chains of alternating [Fe(CN)(6)](3-) and [Cu(cyclam)](2+) units, K+ cations and crystal water molecules. In the crystals the chains are linked by CN-K-NC interactions, to form a two-dimensional layer structure. Magnetic measurements show a weak ferromagnetic intrachain interaction based on the strict orthogonality of the magnetic orbitals of the Fe-III and Cu-II. In the structure of 2 each [Cu(L-1)](2+) unit is bonded to centrosymmetric [Fe(CN)(6)](4-) and [Cu(L)Fe(CN)(6)Cu(L)] units through two cis bridging cyanide ligands. Owing to the symmetry, a unique one-dimensional zigzag chain structure is formed through trans bridging cyanide ligands of the two crystallographically non-equivalent [Fe(CN)(6)](4-) groups. In the course of the reaction the [Fe(CN)(6)](3-) ion undergoes a reduction to [Fe(CN)(6)](4-) whereas the [Cu(L)](2+) ion partly hydrolyses to [Cu(L-1)](2+). Compound 2 is essentially paramagnetic within the chain.