Binuclear Mn complex

III) form of Lactobacillus plantarum is depicted in Fig. 13 [105,106]. The Mn centers are bridged by oxo, hydroxo, and car-boxylato ligands in a manner similar to the binuclear structures (8-10) in Sect. 16.1.4. A proposed mechanism for hydrogen peroxide dismutation by Mn catalase is presented in Fig. 14. A number of model studies of H2O2 disproportionation employing bridged binuclear Mn complexes have been conducted [107]. 

Halogenation of the binuclear Mn complex [Mn(CO)5]2PbPh2 with Cl2 or Br2 cleaves the Pb—C bond rather than the Mn—Pb bond to produce halogenated Mn—Pb derivatives (equation 194, X = Cl, Br487). 

Okawa and co-workers have published several papers in recent years on binuclear catalase mimics based on the pentadentate or sep-tadentate binucleating ligands, an example of which is shown in Scheme 21 (441, 442). These ligands have been used to prepare a variety of binuclear Mn" complexes. Their ability to catalyze the dis-porportionation of hydrogen peroxide varies, but is generally low, on the order of 0.79 s 1. A functional scheme for the disproportionation of hydrogen peroxide has been proposed for these complexes that invokes a MnIV=0 intermediate (Scheme 21). 

The nitrogen atom in ri -pyrrolylmanganesetricarbonyl forms a donor-acceptor bond with transition metals. Complexes in which the pyrrolyl ring behaves as a tt ligand for the manganese atom and n-donor for the other metal were synthesized 12 (M = Mn, Re) [78JOM(157)431]. The binuclear heterobimetallic complexes... 

Stewart s conclusion underscores the need for short-wavelength, low-temperature studies, if very high accuracy electrostatic properties are to be evaluated by Fourier summation. But, as pointed out by Hansen (1993), the convergence can be improved if the spherical atoms subtracted out are modified by the k values obtained with the multipole model. Failure to do this causes pronounced oscillations in the deformation density near the nuclei. For the binuclear manganese complex ( -dioxo)Mn(III)Mn(IV)(2,2 -bipyridyl)4, convergence of the electrostatic potential at the Mn nucleus is reached at 0.7 A" as checked by the inclusion of higher-order data (Frost-Jensen et al. 1995). 

Reactions of mononuclear vinylidene complexes with other reactive metal complexes to give binuclear //-vinylidene complexes have been described above. Addition of Fe2(CO)c, to Mn(C=CHPh)(CO)2(i/-C5H5) also gives 31, by addition of a CO group to the a-carbon structural data are consistent with the delocalized formulation (31b), with its obvious resemblances to trimethylenemethane (60) ... 

Binuclear manganese complexes (55) have been obtained from their mononuclear analogs, either by heating in an inert atmosphere, or by treating them with Mn(OEt2)(CO)2(i C5H5) (74) ... 

Tripodal N2O2 and N3O iminocarboxylate ligands such as (102) and (103) have appeared, with the vanadyl complexes acting as halogenperoxidase models. Binuclear Mn and Mn complexes feature linked MnL units. Related N3O and N2O2 aminoalcohol ligands are known, exemplified by (104), which forms a mononuclear trigonal bipyramidal complex with Cu with acetate or thiocyanate as the additional donor, and (105), which forms a square-pyramidal Fe complex that exhibits catalytic activity as a model for catechol-1,2-dioxidase. 

M. J. Patel, B. M. Trivedi, Synthesis and catalytic activity of binuclear Mn(III,III)-BINOL complexes for epoxidation of olefins, Appl. Organomet. Chem. 20 (2006) 521. 

A particularly interesting example of binuclear Mn electrochemistry is that reported by Holm et al. for the [Mn2(salmp)2]" ( = 2+, 1+, 0,1—, 2—) complex [88]. I l isahrip is a pentadentate SB ligand that bridges both Mn centers by means of a centrally positioned phenolate group (7). [Mn2(salmp)2] undergoes four chemically reversible one-electron transfers. 

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