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.