Synthesis and structural analyses of Co(III) coordination compounds of 2-(2′-pyridyl)benzimidazole and 2-(2-hydroxyphenyl)-1H-benzimidazole

The synthesis and characterization of the tris-chelate Co(III) coordination compounds: [Co(2pb)3] · 2C3H6 · 2 1 2 H2O (3) prepared from 2-(2′-pyridyl)benzimidazole (1), and [Co(2fb)3] · 2C2H5OH · H2O (4) synthesized from (o-hydroxyphenyl)benzimidazole (2) are discussed. The structures of compounds 3 and 4 were determined by NMR spectroscopy. The X-ray crystal analyses of compounds 2–4 were performed. In the cobalt(III) compounds, the deprotonated benzimidazolic ligands form five (1) and six (2) membered rings, respectively. In the first case the ligands are planar, while for the latter the ligands are twisted. The configuration of the metal centre in compounds 3 and 4 corresponds to the less symmetric mer isomer (C1 symmetry). Supramolecular networks are stabilized by the insertion of water molecules able to form hydrogen bonds.