Synthesis and characterization of two cobalt complexes derived from the system containing phenylphosphonic acid

A single-chain cobalt phosphonate complex [Co(phen)(4,4′-bpy)(PhPO3H)2]n·0.5H2O 1 (phen = 1,10-phenanthroline, 4,4′-bpy = 4,4′-bipyridine) and a mononuclear cobalt complex [Co(pic)2(H2O)2]·0.5H2O 2 (picH = picolinic acid) have been synthesized with identical procedure from similar system containing phenylphosphonic acid and N-containing ligands. Both complexes have been characterized by single crystal X-ray diffraction, IR spectroscopy, magnetic measurement and thermal analysis. Compound 1 crystallizes in the tetragonal system with a P43212 space group, and exhibits a 1-D cobalt chain connected by 4,4′-bpy bridges propagated along a axis direction, and the chains are linked by strong hydrogen bonds to form a two-dimensional grid like coordination network, whereas compound 2 crystallizes in the monoclinic system with space group P21/n, and the mononuclear molecules in 2 are linked by hydrogen bonds to form infinite double-chains and the double-chains are further crosslinked to create a two-dimensional supramolecular network. The magnetic measurement reveals overall weak antiferromagnetic exchange interactions between the cobalt ions in both complexes 1 and 2.