Manganese represents an essential trace element that is accumulated and utilized by virtually all forms of life. This redox active metal is a key cofactor for a wide range of metalloenzymes, including oxidases and dehydrogenases, DNA and RNA polymerases, kinases, decarboxylases, and sugar transferases (11, 25). In addition to serving as an essential nutrient, manganese can also be toxic. In hum...

Effect of manganese with three different valence states on carthamin formation was studied by using freshly collected flowers from dyer’s saffron ( C. tinctorius) capitula. At 1 10 hm con­ centration, these cations accelerated markedly the carthamin formation induced by endoge­ nous enzyme(s) in the detached floral tissues. The acceleration was obviously dependent on the valence state of the te...

The chiral ligand S-1,2-bis(1H-benzimidazol-2-yl)ethanol, 1, reacts with manganese(II) salts to form cubanes which readily undergo oxidation reactions leading either to a tetranuclear manganese(II,III) mixed valence complex 4 or to a tetranuclear complex of ligand 5 where the secondary alcohol has been oxidised to an enolate. N-methylation of ligand 1 slows the oxidation reaction and stable man...

A new bis(N2O2) ligand, L(4-), in which two tripodal diamine-bis(phenolate) moieties are bridged by a xanthene backbone, was prepared. The reaction of H4L with 2 equiv. of [Ti(O(i)Pr)4] produced C2 and Cs symmetrical isomers of the dititanium(IV,IV) complex [Ti2(L)(O(i)Pr)4]. The isolated C2 isomer was slowly converted to the Cs isomer via Ti-N bond cleavage to form a 3 : 2 mixture in equilibri...