Synthesis, crystal structures and properties of two new metal complexes of syn-2pyridinealdoxime with a “metallocrown” unit and a 1D double chain structure

Reactions of syn-2pyridinealdoxime (HL) with divalent metal salts in a mixed ethanol/acetonitrile solution resulted in two new metal complexes with different structures. The structure of the zinc complex, Zn4(L)4Cl2(μ3-OH)2 · 4CH3CN (1) features a 12-metallocrown-4 unit. The syn-2pyridinealdoxime ligand adopts a tridentate chelating and bridging coordination mode. The structure of Mn(HL)(SO4)(H2O) (2) contains a double chain along the b-axis, in which the Mn(II) cations are bridged by μ3-SO42− anions. The syn-2pyridinealdoxime ligand chelates with a Mn(II) ion using its two nitrogen atoms. These double chains are further interconnected into a 2D layer parallel to the ab-plane via hydrogen bonds between aqua ligands and the non-coordinated sulfate oxygen atoms. Results of magnetic measurements of complex 2 indicate that there is weak Curie–Weiss behavior with θ=−10(1) K indicating predominant antiferromagnetic interaction between the Mn(II) ions. Indication for magnetic low-dimensional magnetism could not be detected.