Dibromido(2,3,9,10-tetra-methyl-1,4,8,11-tetra-azacyclo-tetra-deca-1,3,8,10-tetra-ene)cobalt(III) bromide.

In the title compound, [CoBr(2)(C(14)H(24)N(4))]·Br, the Co(III) ion is located on an inversion centre and possesses a distorted octa-hedral coordination geometry in which four nitro-gen donors of the ligand mol-ecule are in the equatorial plane and two Br(-) ions occupy both the axial sites to give a trans isomer. The Br(- )counter- anion is also located on an inversion centre.

1-[4-(Diamino-methyl-eneamino-sulfon-yl)phenyl-iminiometh-yl]-2-naphtholate N,N-dimethyl-formamide disolvate.

The asymmetric unit the title compound, C(18)H(16)N(4)O(3)S·2C(3)H(7)NO, contains a mol-ecule in a zwitterionic form with a deprotonated hydroxyl group and an iminium group, and two dimethyl-formamide solvent mol-ecules. The dihedral angles of the guanidine group and the naphthyl ring system with respect to the central benzene ring are 76.04 (7) and 3.

4-[(3-Formyl-4-hydroxy-phen-yl)diazen-yl]-N-(pyrimidin-2-yl)benzene-sulfonamide.

The title mol-ecule, C(17)H(13)N(5)O(4)S, has a trans configuration with respect to the diazenyl (azo) group. The pyrimidine ring and the terminal benzene ring are inclined at angles of 89.38 (4) and 1.

UV/Vis, IR and 1H NMR spectrophotometric studies of some bisazo-dianil compounds based on bis-(hydroxy, formyl) phenylazo phenylene and anthranilic acid.

The electronic absorption spectra of some bisazo-dianils are studied in organic solvents of different polarity and in buffer solutions of varied pH. The different absorption bands are assigned to the corresponding electronic transitions, the solvent effect on the CT band energy is also discussed. The spectral study in buffer solutions is utilized for the determination of the pKa of the phenolic OH-groups.