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Synthesis, Structure and Characterisation of a New Trinuclear Di‐ μ ‐phenolato‐ μ ‐carboxylato Mn III Mn II Mn III Complex with a Bulky Pentadentate Ligand: Chemical Access to Mononuclear Mn IV –OH Entities
Author(s) -
Hureau Christelle,
AnxolabéhèreMallart Elodie,
Blondin Geneviève,
Rivière Eric,
Nierlich Martine
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500501
Subject(s) - chemistry , acetonitrile , electron paramagnetic resonance , manganese , pyridine , crystallography , ligand (biochemistry) , valence (chemistry) , schiff base , inorganic chemistry , medicinal chemistry , nuclear magnetic resonance , biochemistry , physics , receptor , organic chemistry , chromatography
A new trinuclear Mn III Mn II Mn III complex has been isolated and X‐ray characterised, namely [(py‐salpn)Mn III (μ‐OAc)Mn II (μ‐OAc)Mn III (py‐salpn)] 2+ ( 1 ), where H 2 py‐salpn is the new bulky [N 3 O 2 ] ligand derived from the H 2 salpn Schiff base by the addition of one pyridine arm and the reduction of the imine function. The crystal structure reveals that the complex has a strictly 180° Mn III ··· Mn II ··· Mn III angle, the Mn II ion being located at an inversion centre. The complex is valence‐trapped, with the terminal Mn III ions showing a Jahn–Teller elongation along the pyridine–Mn III –acetate axis. The Mn II ··· Mn III separation is 3.1224(13) Å. The EPR spectra recorded on solid and frozen solutions are consistent with an Mn III Mn II Mn III species. The electrochemical response of complex 1 in acetonitrile solution exhibits two, one‐electron reduction waves at E 1/2 = 0.140 and –0.075 V vs. SCE.Phenolato and acetato→Mn III ligand‐to‐metal charge‐transfer transitions are detected by UV/Visible spectroscopy at 359 and 587 nm, respectively. Chemical oxidation of an acetonitrile solution with tert ‐butyl hydroperoxide leads to mononuclear Mn IV –hydroxo species, as evidenced by UV/Visible and EPR spectroscopy as well as ESI mass spectrometry.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)