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Cross cyclotetramerization of bis(4- tert-butylphenyl)fumaronitrile with 1,2,5-selenadiazole-3,4-dicarbonitrile in the presence of magnesium butoxide as template afforded a mixture of magnesium(II) porphyrazine complexes, from which magnesium complex of 5,6,8,9,11,12-hexakis(4- tert-butylphenyl)[1,2,5]selenadiazolo[3,4- b]porphyrazine was isolated by column chromatography and was subjected to demetalation on treatment with trifluoroacetic acid. The free ligand was found to undergo protonation at one meso-nitrogen atom in acid medium and deprotonation of one pyrrole ring to form monoanion by the action of bases. Reductive deselenation of the title compound with formation of vicinal diamino porphyrazine was studied by spectral and kinetic methods, and a mechanism involving two hydrosulfide ions was proposed. [ABSTRACT FROM AUTHOR]

Cross cyclotetramerization of trans-2,3-diphenylbutanedinitrile with 1,2,5-thia(selena)diazole-3,4-dicarbonitriles or phthalodinitrile in the presence of magnesium butoxide gave mixtures of Mg(II) porphyrazine complexes which were treated with trifluoroacetic acid to isolate unsymmetrical hexaphenyl-substituted 1,2,5-thia(selena)diazolo-and benzo-fused porphyrazines together with diphenyltribenzoporphyrazine. Their 1H NMR and electronic absorption spectra (in the UV and visible regions) were recorded. The effect of benzene and heteroring fusion on the electronic and steric structure and spectral properties of porphyrazine derivatives was studied in terms of the molecular orbital perturbation theory and semiempirical quantum-chemical calculations (AM1, PM3, ZINDO/S, CNDO/S). [ABSTRACT FROM AUTHOR]

Cross cyclotetramerization of 1,2,5-thiadiazole-3,4-dicarbonitrile and 4- tert-butylphthalodinitrile in the presence of magnesium butoxide gave a mixture of symmetric and asymmetric porphyrazine magnesium(II) complexes. One of these, (22(3),72(3),122(3)-tri- tert-butyltribenzo[ b,g,l][1,2,5]thiadiazolo[3,4- q]-5,10,15,20-tetraazaporphyrinato)magnesium(II) (MgSBBB), was isolated by column chromatography and was treated with trifluoroacetic acid to obtain the corresponding free ligand (H2SBBB). The effect of the mode of heteroring fusion on the electronic absorption spectra of tribenzoporphyrazines was studied. [ABSTRACT FROM AUTHOR]