Synthesis, Structure and Characterisation of New Phenolato-Bridged Manganese Complexes [L2Mn2]2+ − Formation by Ligand Oxidation in LaH [LaH = N-(2-hydroxybenzyl)-N,N′-bis(2-pyridylmethyl)ethane-1,2-diamine]

Abstract

A mononuclear [L a Mn III OAc](ClO 4 )·0.5H 2 O [2(ClO 4 )·0.5H 2 O] complex with a new amino-containing pentadentate ligand L a H with a [N 4 O] coordination sphere has been obtained. Magnetic susceptibility measurements of 2(ClO 4 )·0.5H 2 O indicated a high spin electronic configuration for the Mn III ion.In cyclic voltammetry the reversible wave observed at E 1/2 = 0.15 V vs. SCE was attributed to the reduction of Mn III into Mn II . In acetonitrile solution complex 2 spontaneously evolved into phenolato-bridged Mn II Mn II dimeric complexes with the concomitant oxidation of the ligand. X-ray diffraction structures revealed that there is indeed a 1:1 mixture of two closely related complexes: in one case both ligands L a − have been oxidised to the imine form leading to the [L i Mn II Mn II L i ] 2+ cation (1a), whereas in the other, only one ligand has been oxidised, leading to the [L a Mn II Mn II L i ] 2+ cation (1b). In both 1a and 1b, Mn II ions are in a distorted octahedral environment. Crystallographic data indicated that the Mn 2 O 2 core is similar for 1a and 1b. The complete spectroscopic and electrochemical studies performed on powder

A new, dinuclear high spin manganese(III) complex with bridging phenoxy and methoxy groups. Structure and magnetic properties

“…The fourth is considerably longer, probably due to the Jahn-Teller effect, with an Mn1-O1 distance of 2.215(2) Å , which is close to the axial bond in a related pentaphenolato Mn III -Mn III complex [14]. The equatorial Mn-N distances (2.089-2.146) are in the range observed for a series of similar Mn III complexes [14,17,19] and about 0.1 Å shorter than in related Mn II complexes [16,18].…”

“…A Mn V @O moiety has been proposed to play a key-role in OAO bond formation in photosynthesis as well as a model complex [9][10][11]. It is therefore of interest to study and characterize highvalent dinuclear manganese complexes, and we and others have prepared a number of dinuclear manganese complexes, which have oxidation states between Mn II and Mn IV and a varied number of coordinating phenoxy groups, which could be expected to stabilize high oxidation states of manganese [12][13][14][15][16][17][18]. These studies include the dinuclear Mn II,III complex 3, which was first prepared by Hendrickson et al [19] This complex was found to give a fairly stable Mn III,IV complex, which, however, appears to decompose on further oxidation [20,21].…”

A Zig‐Zag [MnII4] Cluster from a Novel Bis(β‐diketonate) Ligand

“…Such a type of link between divalent Mn centers has been reported to lead to both, ferro- [31,[36][37][38][39] and antiferromagnetic interactions. [40][41][42][43] The actual magnetic behaviour depends strongly on the efficiency of the overlap between d x 2 -y 2 orbitals of the metal ions through the phenoxide Odonors, which is considered the main pathway to antiferromagnetism. In 1, the latter is expected to be much reduced, given the weakening of antiferromagnetic pathways that might be caused by the severe distortion in the coordination geometry shown by the metal ions.…”

Intramolecular oxidation of the ligand 4-methyl-2-N-(2-pyridylmethyl)aminophenol (Hpyramol) upon coordination with iron(II) chloride and manganese(II) perchlorate

“…The Mn(II) ion is in a distorted octahedral environment. Therefore, according to the ligand field theory and assuming an O h symmetry, the ground state of manganese(II) is 6 A 1g . Because d-d transitions of Mn(II) ( 6 A 1g !…”

“…Consequently, polydentate N,O-containing ligands are continuously developed both to prepare catalysts, and to model the active site of enzymes [5,6].…”