Manganese complexes salicylates

Mn(III). Structurally characterized higher valent manganese complexes with phenoxide-type ligation are limited to Mn(III) and Mn(IV) Schiff base complexes (128-135), Mn(III) and Mn(IV) catecholates (136-139), Mn(III) and Mn(IV) salicylates (140-142), and Mn(III) bi-phenoxides (143). However, of these ligands, only biphenoxide is similar electronically to tyrosine Mn(III) complexes of these ligands, in general, lack the intense phenoxide - metal charge transfer band centered at 435 nm. 

However, Oberley and Buettner pointed out that all tumour cell lines have markedly decreased superoxide dismutase activity [355]. The marked decrease in manganese-dependent SOD activity is consistent with a decrease in aerobic metabolism and a decrease or only a modest increase in Cu-Zn SOD activity is consistent with an impaired response leading to transformation. As a result of the observed lowered SOD activities in tumour cells and an awareness of the SOD-mimetic activity of copper salicylate complexes, salicylate and other copper complexes were investigated as antitumour agents. 

A PRP -1 (Hamilton Reno, NV) reversed phase column was coated with cetylpyridinium and eluted with tetramethylammonium salicylate acetoni-trile water.89 The separation was comparable to that observed on conventional ion exchange. Coated phases were also used to separate oxalate complexes of manganese, cobalt, copper, and zinc.90 Reversed phase silica supports were coated with poly(N-ethyl-4-vinylpyridinium bromide), poly(dimethydiallylammonium chloride), poly(hexamethyleneguanidinium... 

The aromatic dihydroxylated ligands (represented by catechol, 2,3-dihydroxybenzoate, and 4,5-dihydroxynapthalene 2,7-disulfonate) stabilize the 3+ and 2+ oxidation states of manganese in alkaline media. The data for salicylate indicate that it forms a less stable Mn(III) complex than the dihydroxy ligands. Formation of the 4+ complex is precluded because the ligands are more easily oxidized than are the Mn(III) complexes. 

Structurally characterized trivalent manganese imidazole or imid-azolate complexes are also extremely rare. Current examples are limited to Mn(III) porphyrins (61), Mn(III) thiolates (Section III,B)> a Mn(III) salicylate complex (Section IV,B) and Mn(III) and Mn(IV) carboxylate complexes (Section VI,B) (62). None of these complexes contains a Mn-to-imidazole ratio greater than two consequently, no structural model for Mn SOD exists presently in Mn coordination chemistry. However, a five-coordinate Mn(II) monomer with three imidazole ligands, Mn(2-Me-ImH)3Cl2 (ImH = imidazole), has been characterized by X-ray diffraction techniques (63). 

USE OF SALICYL- AND NAPHTHOYLHYDROXIMATE COMPLEXES IN PREPARATION OF MANGANESE AND COPPER 12-METALLACROWN-4 COMPLEXES Mn(II)(ACETATE)2[Mn(III)(SALICYLHYDROXIMATE)]4 AND (TETRAMETHYLAMMONIUM)2[Cu(n)5 (NAPHTH0YLHYDR0XIMATE)4]... 

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