Polynuclear manganese amino acid complexes

Abstract

The reaction of MnCl(2).4H(2)O with DL-valine (Val) in MeOH in the presence of Et-saoH(2) (2-hydroxypropiophenone oxime) and NEt(4)OH forms the complex [Mn(III)(3)Mn(IV)(2)O(2)(CH(3)O)(Et-sao)(6)(Val)].Val.1.5H(2)O (1.Val.1.5H(2)O) in very good yields. A similar reaction of MnCl(2).4H(2)O with Glycine (Gly) in MeOH in the presence of saoH(2) (salicylaldoxime) and Ca(OH)(2) yields the complex [Mn(III)(3)O(sao)(3)(Gly)Cl(MeOH)(3)].1.87 MeOH.0.13H(2)O (2.1.87 MeOH.0.13H(2)O). Replacing saoH(2) with Me-saoH(2) (2-hydroxyethanone oxime) and Gly with HPABA (para-aminobenzoic acid) in the presence of CH(3)ONa in MeOH forms the complex [Mn(6)O(2)(PABA)(2)(Me-sao)(6)(MeOH)(4)(H(2)O)(2)].2[Mn(6)O(2)(PABA)(2)(Me-sao)(6)(MeOH)(2)].11 MeOH (3.11 MeOH) in moderate yields. Magnetic studies for 1 and 2 reveal the presence of both ferromagnetic and antiferromagnetic interactions, leading to S = 2 ground states for both complexes. Complexes 1 and 2 represent the first examples of polynuclear manganese complexes with any naturally occurring alpha-amino acid, while 3 is the first structurally characterised example of a manganese para-aminobenzoate complex.

The Role of the −OH Groups within Mn12Clusters in Electrocatalytic Water Oxidation

“…[14,18] Mimicking nature's strategy by adjusting the ligation about the active site to have proton-accepting groups can be therefore useful in the design of artificial water oxidation catalysts. [17][18][19][20][21] These ligands can be either organic or inorganic; [22,23] the utilization of both types lead to the development of polynuclearh igh oxidation manganese clusters [24][25][26] as larger nuclearity mimics of the OEC.…”

A 1D copper(II) chain featuring novel hexanuclear secondary building blocks: Synthesis, crystal structure and magnetic property

“…The hexanuclear unit is formed by the assembly of two tetranuclear subunits via two public copper ions coordinating simultaneously to two L 6− ligands, and the 1D chain structure of the compound is constructed by the connection of the hexanuclear units via the bridging of the phenolic oxygen atoms of the L 6− ligands. The magnetic study of the compound indicates an antiferromagnetic coupling interaction between Cu(II) ions.The syntheses and properties of discrete polynuclear complexes and coordination polymers ranging from 1D to 3D have attracted great research interest for many years because of their intriguing architectures and potential applications in catalysis, electronics, nonlinear optics, magnetic materials, porous materials, as well as their relevance to bioinorganic chemistry [1][2][3][4][5][6][7][8][9][10][11]. It is well known that the careful selection of the organic ligands is one of the key factors for the synthesis of the coordination compounds with novel structures.…”

A New “Offset” Analogue of the Classical Oxime-Bridged [MnIII6] Single-Molecule Magnets

“…When the reaction is carried out in methanol, the previously reported triangular [Mn 3 O(naphthsao) 3 (CH 3 OH) 5 (CH 3 COO)] complex is isolated. 4 The possibility of the related [Mn 6 O 2 ] analogue formation was already proved by Milios et al 6 An interesting compound with a novel modification was introduced, cocrystallizing with the classical core complex. No detailed magnetic property characterizations were reported due to the presence of the two molecular species in one crystal structure.…”

“…Oxime-bridged [Mn 6 O 2 ]-core complexes are an important and well-characterized group of compounds in terms of magnetostructural correlations. 1 Classical examples are the [Mn III 6 O 2 -(Et-sao) 6 (O 2 CPh) 2 (EtOH) 4 (H 2 O) 2 ] 2a and [Mn III 6 O 2 (Et-sao) 6 -(O 2 CPh(Me) 2 ) 2 (EtOH) 6 ] 2b clusters following the "magic angle theory". 2 In this theory, the dominant magnetic coupling within the [Mn 6 O 2 ] core is governed by the value of the torsion angle Mn−N−O−Mn.…”