Distinct 2-D and 3-D Co(II) coordination polymers with 5-bromonicotinate induced by different synthetic approaches

Two distinct Co(II) coordination polymers [Co(L-Br)2(H2O)2]n (1) and {[Co(L-Br)2(H2O)0.5](H2O)0.5}n (2) have been prepared from 5-bromonicotinic acid (HL-Br) by using different synthetic approaches (ambient condition vs hydrothermal method). Both complexes have been characterized by elemental analysis, IR, and powder X-ray diffraction. Single crystal X-ray diffraction reveals that 1 displays a 2-D (4,4) polymeric layered network whereas 2 presents a 3-D unusual binodal (3,6)-connected net of (3.4.5)(32.44.55.62.72) topology. Their structural divergences should be properly attributed to the different coordination patterns of L-Br− and water ligands. In addition, thermal stability and magnetic properties of both complexes are also studied.