Synthesis and Characterization of Some New Manganese(II) Complexes, Manganese(III) Heterochelates, and µ‐Dioxo‐dimanganese(IV) Complexes Involving Tetradentate Schiff Bases

Abstract

Condensation of 1,3‐diaminopropane‐2‐ol with diacetylmonoxime and acetylacetone yielded the tetradentate Schiff bases N,N′‐(2‐hydroxy)propylene‐bis{(2‐imino‐3‐oximino)butane} (H₂L¹) and N,N′‐(2‐hydroxy)propylene‐bis(acetylacetoneimine) (H₂L²), respectively. The ligands form mononuclear manganese(II) complexes of the type [Mn(II)(L¹)] (1) and [Mn(II)(L²)] (3), which are used for the formation of the manganese(III) heterochelates of the type [Mn(III)(L)(L‐L)] (where H₂L = H₂L¹ or H₂L²; L‐L = anion of acetylacetone or salicylaldehyde). Cationic heterochelates of the type [Mn(L)(L‐L)]ClO₄ where H₂L = H₂L¹ or H₂L² and L‐L = ethylenediamine and N,N′‐propylene‐bis(benzaldimine) (L³) have been synthesized by the reactions of bis(acetylacetonato)manganese(II) or bis(salicylaldehydato)manganese(II) with the preformed Schiff bases or by the reactions of [Mn(II)(L¹)] or [Mn(II)(L²)] with L‐L in absolute alcohol under reflux. Some of the complexes, synthesized here, may be used as precursors in the synthesis of higher nuclearity manganese complexes. Air oxidation of [Mn(II)(L¹)] (1) and [Mn(II)(L²)] (3) in DMF yielded the dark‐brown µ‐dioxo‐bis‐[N,N′‐(2‐hydroxy)propylene‐bis{(2‐imino‐3‐oximino)butane}]dimangenese(IV) (2) and µ‐dioxo‐bis[N,N′‐(2‐hydroxy)propylene‐bis{(acetylacetoneimine)}]dimangenese(IV) (4) complexes, respectively. All of the complexes have been characterized with the help of elemental analyses, molar conductance values, molecular weights, magnetic moments, and spectroscopic (IR, UV‐VIS, ESR) data.

Keywords:

• Manganese(II) complexes
• Manganese(III) heterochelates
• μ‐Dioxo‐dimanganese(IV) complexes
• Tetradentate Schiff bases

Acknowledgments

The work was financially supported by the University of Kalyani. The authors are thankful to the Regional Sophisticated Instrumentation Centre, Central Drug Research Institute, Lucknow, India for elemental analyses and spectral data.