Role of hydrogen peroxide in the synthesis of nitrogen heterocycle containing cobalt complexes

The reactions of Co(O2CCH3)2·4H2O with the sodium salt of p-toluene sulfonic acid (NapTS) and pyridine (py) or 4-methylpyridine (4mepy) in the presence of hydrogen peroxide in methanol led to the formation of [Co(py)3(H2O)3](pTS)2 or [Co(4mepy)2(H2O)4](pTS)2·MeOH, respectively. The coordination polymer [{Co(44′bpy)(H2O)4}(pTS)2]n (4,4′-bipyridine = 44′bpy) was obtained from the reaction of Co(O2CCH3)2·4H2O with 44′bpy in the presence of NapTS. The reaction of Co(O2CCH3)2·4H2O, 2,2′-bipyridine (22′bpy) and NapTS with hydrogen peroxide resulted in the formation of the dinuclear complex [Co2(μ-OH)2(μ-O2CCH3)(O2CCH3)2(22′bpy)2](pTS). Characterization of these complexes and the role of hydrogen peroxide in these reactions are discussed. Similar reactions with sodium sulfamate gave the mononuclear [Co(22′bpy)2(O2CCH3)]NH2SO3·2H2O complex and [Co2(μ-OH)2(μ-O2CCH3)(O2CCH3)2(22′bpy)2](NH2SO3).

Graphical abstractThe role of hydrogen peroxide in the synthesis of [Co(py)3(H2O)3](pTS)2 and [Co(H2O)4(4mepy)2](pTS)2·MeOH (pyridine = py, 4-methylpyridine = 4mepy, para-toluene sulfonate = pTs) is described. A binuclear complex [Co2(μ-OH)2(μ-O2CCH3)(O2CCH3)2(22′bpy)2](pTS), is prepared under ambient conditions and characterized.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The role of hydrogen peroxide in the synthesis of cobalt (II) complexes is described. ► The structures of mononuclear cobalt complexes containing p-toluenesulphonate are described. ► An hydroxo bridged dinuclear cobalt (III) complex with 2,2′-bipyridine is prepared under ambient conditions. ► A channel-like structure in a cobalt (II) coordination polymer of 4,4′-bipyridine is shown.