Synthesis and characterization of some novel cadmium(II) complexes with 3-hydroxypicolinic acid (3-OHpicH):: Crystal and molecular structures of [CdI(3-OHpic)(3-OHpicH)(H2O)]2, [Cd(3-OHpic)2(H2O)2] and [Cd(3-OHpic)2]n

Cadmium(II) complexes of 3-hydroxypicolinic acid, namely [Cd1(3-OHpic)(3-OHpicH)(H2O)](2) (1), [Cd(3-OHpic)(2)(H2O)(2)] (2) and [Cd(3-OHpic)(2)](n) (3) were prepared and characterized by spectroscopic methods (IR, NMR) and their molecular and crystal structures were determined by X-ray crystal structure analysis. Complexes 1 and 2 were prepared in similar reaction conditions using different cadmium(II) salts: cadmium(II) iodide and cadmium(II) acetate dihydrate, respectively, while 3 was prepared by recrystallization of 2 from N,N-dimethylformamide solution. Various coordination modes of 3-OHpicH in 1-3 were established in the solid state: bidentate N,O-chelated mode in 1 and 2, monodentate mode through the carboxylate 0 atom from zwitterionic ligand in 1 and bidentate N,O-chelated and bridging mode in 3. In the DMF solution of all prepared complexes, only monodentate mode of 3-OHpicH binding to cadmium(II) through the carboxylate O atom was established by H-1, C-13, N-15 and Cd-113 NMR spectroscopy. (C) 2008 Elsevier Ltd. All rights reserved.