Manganese complexes phthalocyanines

Kimer JF, Dow W, Scheldt WR. 1976. Molecular stereochemistry of two intermediate-spin complexes. Iron(II) phthalocyanine and manganese(II) phthalocyanine. Inorg Chem 15 1685-1690. 

In contrast to the ionic complexes of sodium, potassium, calcium, magnesium, barium, and cadmium, the ease with which transition metal complexes are formed (high constant of complex formation) can partly be attributed to the suitably sized atomic radii of the corresponding metals. Incorporated into the space provided by the comparatively rigid phthalocyanine ring, these metals fit best. An unfavorable volume ratio between the space within the phthalocyanine ring and the inserted metal, as is the case with the manganese complex, results in a low complex stability. 

Porphyrins, 21 14, 36, 135 -based manganese complexes, 46 400-402 as cobalt complex ligants, 44 284-290 compared to phthalocyanines, 7 75 complexes, 19 144, 145, 147 complex stability, 42 135-137 degeneracy lifting, 36 206 metalloporphyrins, DNA cleavage and, 45 271-283... 

Manganese complexes of 2[(l-hydroxy-2-naphthalenyl)carbonyl]benzoic acid (12) are reported to be effective photostabilizers for polymers,47 and manganese phthalocyanine shows smoke-retarding properties in polystyrene.31... 

Reduction of manganese(ii) phthalocyanine with sodium in THF or by electrochemical methods produces four distinct anionic complexes corresponding to the stepwise addition of electrons. Electronic spectra of the reduced species indicated that the added electrons are confined essentially to phthalocyanine ring orbitals. ... 

Phthalocyanlnes. Gebler (18) has reported the attachment of a variety of metal phthalocyanines to both 8% and 20% dlvlnylbenzene polystyrene copolymer beads. The attachment of the phthalocyanine unit was either ly a sulfonamide or a sulfone linkage. Nickel, vanadyl, cobalt, iron and manganese complexes were formed in this way. Since solution aggregation accounts for a diminution of the catalytic activity, it was anticipated that polymer immobilization would Increase reactivity. Such an effect was not observed and little advantage over the homogeneous catalysts could be observed in the oxidation of cyclohexene. Oxidations of thiols by immobilized phthalocyanines have been reported (19-20) by both Schutten and Brouwer. 

The interaction of manganese(II) phthalocyanine with dioxygen in N,N-dimethylacetamide yields a superoxo complex (Pc)Mn (0 ), which... 

Figure 10.12 2,17-Bis-sulfonato-5,10,15-tri(pentafluorophenyl)corrole manganese complex 14 [59,60], tetrakis(sulfonato) phthalocyanin copper complex 15 [61], and meso-tetrakis (p-carboxyphenyl)-porphyrln manganese complex 16 [62].

Most catalysts investigated usually have Fe and Co as metal centers. However, complexes of other metals have also been studied. For example, CrTSPc and MnTSPc exhibit catalytic activity for ORR [14] and they somehow resemble the behavior of Fe complexes, especially MnTSPc, in the sense that it shows a prewave where O2 reduction proceeds entirely via four electrons to give water. Peroxide is produced at higher polarizations. The lower activity of Cr and Mn phthalocyanines compared to Fe phthalocyanines can be attributed to their low redox potential, that is, they are easily oxidized [82, 105]. The activity of most macrocyclic metal complexes increases after heat treatment [145]. However, the opposite is observed for manganese complexes probably because the metal is lost from the N4 stmcture. So, most work dealing with heat-treated materials has focused on Fe and Co macrocycles. Complexes of Mo can only be used in alkaline solution since they are not stable in acid media. MoNPc is less activity than FeNPc as reported by Magner [146]. 

Kirner, J., Dow, W. and Scheldt, W. (1976). Molecular Stereochemistry of Two Intermediate-spin Complexes. Iron(Ii) Phthalocyanine and Manganese(Ii) Phthalocyanine, Inorg. Chem., 15, pp. 1685-1690. 

Manganese(II)-A/, A/r -dipyridoxylethylenediamine-A/r, AT-diacetate 5,5 -bis(phosphate) 75 (DPDP) is clinically used for enhancing contrast in the liver (detection of hepatocellular carcinomas) (312). Some dissociation of Mn(II) appears to occur in the liver, and enhancement can also be obtained in functional adrenal tissues (313). Manganese(II)-tetrasulfonated phthalocyanine also shows tumor localization properties and is a more efficient relaxation agent than the analogous Gd(III) complexes (314). 

Reaction of the manganese tropocoronand complex [Mn(tc-5,5)(NO)] with [Fe(tc-5,5)] results in complete transfer of the NO to the [Fe(tc-5,5)]. Other nitric oxide complexes appear in the sections on nitroprusside (Section S.4.2.2.6 above), on phthalocyanines (Section 5.4.3.7.4 above), and on polynuclear iron-sulfide complexes (Roussin s salts Section 5.4.5.9.2 below) Fe-por-phyrin-NO redox chemistry has been mentioned in Section 5.4.3.7.2 above. 

A number of studies of phthalocyanine and porphyrin complexes of manganese have been carried out and it is clear that both MnIn and MnlV complexes can be photoreduced in the presence of water or OH- and in the absence of an electron acceptor.309 313 These complexes can be produced from Mn11 or Mnm complexes in the presence of an electron acceptor e.g. quinones,314 and the reaction can be sensitized by, for example, zinc porphyrins in suitable model membrane environments.310... 

The tetrasulfo-Pc complexes of a number of metals are made by the urea melt process by heating the powdered metal, or its acetate, with triammonium-4-sulfophthalate, urea, boric acid, and ammonium molybdate. The metals or metal compounds used are those of chromium (III), manganese(II), iron(II), iron(III), cobalt(II), and zinc(II). Selected synthetic examples of sulfo- and other derivatives of metal phthalocyanines are presented below. 

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