Di(phenoxo)-bridged Dinuclear Mn2(II,II) and Mn2(II,III) Complexes of Macrocyclic Ligands: Structure, Properties, and Catalase-Like Function

Dinuclear Mn2(II,II) complexes [Mn2(Lm,n)(RCOO)2] ((m,n) = (2,3), (2,4), (3,3); R = CH3, C6H5) have been prepared where (Lm,n)2− denotes dinucleating macrocycles with two 2,6-bis(iminomethyl)-4-methylphenolate entities combined through two lateral chains, –(CH2)m– and –(CH2)n–, at the imino nitrogens. The complex [Mn2(L3,3)(CH3COO)2] crystallizes in the monoclinic space group P21/n with a = 18.795(5), b = 7.608(2), c = 10.081(1) A, β = 92.89(2)°, V = 1439.7 A3, and Z = 2. The refinement converges with R = 6.38 and Rw = 9.63% based on 2727 reflections with |Fo| ≥ 3σ(|Fo|). A pair of Mn(II) ions are bridged by the two phenolic oxygens with a Mn–Mn separation of 3.367(1) A. An acetate group coordinates bidentately to each Mn(II) to afford a six-coordinate geometry about the metal ion. The oxidation of [Mn2(L3,3)(CH3COO)2] with Br2 forms a mixed-valence Mn2(II,III) complex [Mn2(L3,3)(CH3COO)Br2]·H2O. The Mn2(II,II) and Mn2(II,III) complexes show catalytic activity for decomposing H2O2 in DMF or DMSO. The invo...

[1]  G. Dismukes,et al.  Structural and functional models of the dimanganese catalase enzymes. 3. Kinetics and mechanism of hydrogen peroxide dismutation , 1994 .

[2]  D. E. Fenton,et al.  Heterodinuclear CuIIPbII and CuIIMII (M = Mn, Fe, Co, Ni, Cu, Zn) complexes of macrocycles with dissimilar 4- and 5-coordination sites : synthesis, structures, and properties , 1993 .

[3]  D. Hodgson,et al.  Heteronuclear trinuclear complex ions of the type [MII{Cr(A)4(OH)2}2]4+ , 1993 .

[4]  D. Ash,et al.  EPR evidence for binuclear manganese(II) centers in rat liver arginase , 1992 .

[5]  D. Blow,et al.  Mechanism for aldose-ketose interconversion by D-xylose isomerase involving ring opening followed by a 1,2-hydride shift. , 1993, Journal of molecular biology.

[6]  P. A. Vigato,et al.  The activation of small molecules by dinuclear complexes of copper and other metals , 1990 .

[7]  A. Downard,et al.  Binuclear manganese(II) and nickel(II) complexes with a potentially octadentate macrocyclic ligand (H4L1): synthesis and characterisation. X-ray crystal structures of [Mn2(H2L1 )(CH3COO)2]·2CH3OH and [Ni2(H2L1 )(H2O)2Cl2]·2H20 , 1990 .

[8]  H L Carrell,et al.  X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator. , 1991, Proceedings of the National Academy of Sciences of the United States of America.

[9]  C. Bender,et al.  EPR spectral evidence for a dinuclear active site in the Lactobacillus plantarum manganese catalase , 1988 .

[10]  P. Boyd,et al.  Valence trapping in mixed-valence MnIIMnIII complexes of a macrocyclic binucleating ligand , 1988 .

[11]  H. Follmann,et al.  Ribonucleotide reductase of Brevibacterium ammoniagenes is a manganese enzyme. , 1988, European journal of biochemistry.

[12]  O. Kahn.  Magnetism of the heteropolymetallic systems , 1987 .

[13]  G. Allgood,et al.  Characterization of a manganese-containing catalase from the obligate thermophile Thermoleophilum album , 1986, Journal of bacteriology.

[14]  Glen B. Deacon,et al.  Relationships between the carbon-oxygen stretching frequencies of carboxylato complexes and the type of carboxylate coordination , 1980 .

[15]  H. O̅kawa,et al.  Binuclear Metal Complexes. III. Preparation and Properties of Mononuclear and Binuclear Copper(II) and Nickel(II) Complexes of New Macrocycles and Their Related Ligands , 1972 .

[16]  R. Robson,et al.  Complexes of binucleating ligands. III. Novel complexes of a macrocyclic binucleating ligand , 1970 .

[17]  F. Urbach,et al.  Circular dichroism of square-planar, tetradentate Schiff base chelates of copper(II) , 1969 .

[18]  B. Bosnich.  An interpretation of the circular dichroism and electronic spectra of salicylaldimine complexes of square-coplanar diamagnetic nickel(II) , 1968 .