Manganese(II) complexes of 2,3,5,6-tetra-(2-pyridyl)pyrazine – Syntheses, crystal structures, spectroscopic, magnetic and catalytic properties

A systematic studies on complex formation between Mn(II) ions, 2,3,5,6-tetra(2-pyridyl)pyrazine and halide or pseudohalide (N3−, NCS− and N(CN)2−) ligands have been carried out and the following complexes [Mn2(μ-Cl)2Cl2(tppz)2] (1), [Mn2Cl2(μ-N3-κN1)2(tppz)2] (2), [MnCl(SCN)(tppz)(H2O)]·H2O (3), [MnCl(dca)(tppz)(H2O)0.57(MeOH)0.47] (4), [Mn(NO3)2(tppz)(H2O)] (5), [Mn(N3)(NO3)(tppz)(H2O)] (6), [Mn(SCN)2(tppz)] (7) and [Mn(NO3)(dca)(tppz)]n (8) have been obtained. The compounds were characterized by elemental analysis, IR, EPR, magnetic measurements and X-ray analysis. Two of them (5 and 6) have been tested as catalysts in oxidation of alcohol to aldehydes/ketones using oxone (2KHSO5·KHSO4·K2SO4) as an oxidant under biphasic reaction conditions (CH2Cl2/H2O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature and as catalysts in oxidation of sulfides to sulfoxides with UHP (urea hydrogen peroxide) as oxidant.

Graphical abstractSeveral novel manganese(II) complexes of 2,3,5,6-tetra(2-pyridyl)pyrazine have been synthesised and characterised by means of elemental analysis, IR, EPR, magnetic measurements and single crystal X-ray analysis. Two of them, [Mn(NO3)2(tppz)(H2O)] and [Mn(N3)(NO3)(tppz)(H2O)], have been tested as catalysts in oxidation of alcohol to aldehydes/ketones using oxone (2KHSO5·KHSO4·K2SO4) as an oxidant under biphasic reaction conditions (CH2Cl2/H2O) and tetra-n-butylammonium bromide as phase transfer agent under air at room temperature and as catalysts in oxidation of sulfides to sulfoxides with UHP (urea hydrogen peroxide) as oxidant.Figure optionsDownload full-size imageDownload as PowerPoint slide