Preparation and structures of trinuclear manganese(II) complexes with N-2-pyridiylmethylidene-2-hydroxy-5-substituted-phenylamine

doi:10.1016/S1387-7003(02)00718-9

Inorganic Chemistry Communications

Volume 6, Issue 2, February 2003, Pages 193-196

https://doi.org/10.1016/S1387-7003(02)00718-9 Get rights and content

Abstract

The trinuclear manganese(II) complexes, [Mn^II₃(OAc)₄(pap)₂(H₂O)₂] and [Mn^II₃(OAc)₄(5-Cl-pap)₂(MeOH)₂] were prepared by the reaction of tridentate Schiff base ligands X-papH (X=H, Cl), [N-2-pyridiylmethylidene-2-hydroxy-5-substituted-phenylamine], and Mn^II(OAc)₂·2H₂O. In the molecular structures of these complexes, two terminal manganese ions are coordinated with one oxygen and two nitrogen atoms of X-pap, two oxygen atoms of OAc⁻ and a solvent molecule, to form a distorted octahedral structure where the central manganese ion resides on a center of symmetry and is surrounded by an O₆ donor set of four oxygen atoms from four bridging OAc⁻ and two phenolic oxygen atoms of two X-pap ligands.

Introduction

The chemistry of manganese complexes is of interest as models for biological redox systems involving manganese ions, such as the oxygen-evolving center (OEC) of Photosystem II in green plants, superoxide dismutases (SOD) and Mn-catalases (CAT). In the past two decades, polynuclear manganese complexes have been extensively prepared and characterized as structural and functional models for the above manganese-containing systems [1], [2], [3], [4], [5], [6].

Linear trinuclear manganese complexes bridged by acetato anions have been recently reported [7], [8], [9], [10], [11], [12], [13]. In this paper, we describe the preparation and structures of trinuclear manganese(II) complexes obtained by the reactions of Mn^II(OAc)₂·2H₂O and tridentate Schiff base ligands papH and 5-Cl-papH (see Fig. 1), where papH and 5-Cl-papH denote [N-2-pyridiylmethylidene-2-hydroxy-phenylamine] and [N-2-pyridiylmethylidene-2-hydroxy-5-chloro-phenylamine], which were derived from pyridine-2-aldehyde and 2-amino-phenol and 2-amino-4-chloro-phenol, respectively.

Section snippets

Preparation of trinuclear manganese(II) complexes

The trinuclear manganese(II) complex, [Mn^II₃(OAc)₄(pap)₂(H₂O)₂] (1) was prepared by the reaction of papH (0.298 g, 1 mmol) and Mn^II(OAc)₂·2H₂O (0.276 g, 1.5 mmol) in methanol (MeOH, 400 ml) with stirring at room temperature for 30 min. The resulting red solution was allowed to stand in the dark. After 12 h, the resulting red crystals were collected on a glass filter, and dried in vacuo. The yield was 75.6%. [Mn^II₃(OAc)₄(5-Cl-pap)₂(MeOH)₂] (2) was obtained by the same manner in 68.0% yield.

Structure of trinuclear manganese(II) complexes

Fig. 2, Fig. 3 show the molecular structures of trinuclear manganese(II) complexes [Mn^II₃(OAc)₄(pap)₂(H₂O)₂] (1) and [Mn^II₃(OAc)₄(5-Cl-pap)₂(MeOH)₂] (2), respectively. For both trinuclear manganese(II) complexes, two terminal manganese ions are coordinated with one oxygen and two nitrogen atoms of pap, two oxygen atoms of OAc⁻ and one oxygen atom of water for 1 and MeOH for 2, respectively, to form a distorted octahedral structure. The central manganese ion resides on a center of symmetry and

Supplementary data

Supplementary data are available from the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, deposition numbers 189983 and 189984 for complexes 1 and 2, respectively.

Acknowledgements

This work was partially supported by a grant based on High-Tech Research Center Program for private Universities from the Japan Ministry of Education, Culture, Sports, Science and Technology.

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Inorganic Chemistry Communications

Abstract

Introduction

Section snippets

Preparation of trinuclear manganese(II) complexes

Structure of trinuclear manganese(II) complexes

Supplementary data

Acknowledgements

References (16)

Polyhedron

Adv. Inorg. Chem.

Manganese Redox Enzymes

Chem. Rev.

Chem. Rev.

Chem. Rev.

Coord. Chem. Rev.

Angew. Chem. Int. Ed. Engl.

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