Template synthesis in the nickel(II)–thiocarbohydrazide–propanone triple system

The complexing process proceeding in the Ni^II–thiocarbohydrazide (H₂N–H–NC(=S)–NH–NH₂)–propanone triple system in EtOH solution and nickel(II)hexacyanoferrate(II) gelatin-immobilized matrix has been studied. It has been found that in the first case, template synthesis leading, as a minimum, to formation of three coordination compounds of Ni^II with (N,N,S,S)-donor tetradentate ligands having NiL¹, NiL² and NiL³compositions where L¹ is 4,6,6-trimethyl-2,3,7,8-tetraazanonen-3-di(thiohydrazide)-1,9, L² is 4,6,6,12-tetrametyl-1,9-dithio-2,3,7,8,10,11-hexaazatridekadien-3,11-hydrazide-1 and L³ is 2,8,10,10,16-pentamethyl-5,13-dithio-3,4,6,7,11,12,14,15-octaazaheptadekatrien-2,7,15 is observed, whereas in the gelatin-immobilized matrix, a complexing process in the system considered does not occur.     

Some peculiarities of the molecular structure of porphine and its complexes

A qualitative analysis of certain peculiarities of the porphine molecule and its complexes compared with the phthalocyanine molecule is made by evaluating the -electron charges of bonds in these compounds by means of G. V. Bykov's semi -empirical linear equation. Acid-base, oxidation-reduction, and coordination properties of porphine are examined. It is shown that differences in chemical properties of porphines and tetraporphines can be explained by differences in -electron charges of bonds.     

Manganese Complexes with Octaphenyltetraazaporphine: Acid–Base Interactions and Kinetic Stability in Proton-Donor Solvents

Complexes of manganese(III) and manganese(V) with octaphenyltetraazaporphine (H₂OPTAP) were synthesized. Acid–base interactions of these complexes in the CH₂Cl₂–CF₃COOH system and kinetics of their dissociation in concentrated sulfuric acid, as well as kinetics of octaphenyltetraazaporphine destruction in sulfuric acid solutions were studied by spectrophotometric methods. Acid–base interactions in CH₂Cl₂–CF₃COOH were shown to involve two macrocyclic meso-nitrogen atoms in succession. Concentration stability constants of the acid forms obtained pK ₁ = 0.29 ± 0.01 and pK ₂ = –0.62 ± 0.08 for (chlorine)manganese(III)octaphenyltetraazaporphine ((Cl)MnOPTAP); pK ₁ = 0.99 ± 0.02 and pK ₂ = – 0.70 ± 0.03 for (nitrido)manganese(V)octaphenyltetraazaporphine ((N)MnOPTAP). The rate of dissociation of the complexes in 94–98% H₂SO₄ does not depend on the acid concentration. The manganese(V) complex is three times as stable as the manganese(III) complex.     

Kinetics of the metal-exchange reaction of deuteroporphyrin and gematoporphyrin cadmium complexes with cobalt chloride in acetonitrile

The metal-exchange reaction of cadmium deuteroporphyrin (CdDP) and cadmium gematoporphyrin (CdGP) with cobalt chloride in acetonitrile is studied spectrophotometrically. The stoichiometry of the metal-exchange reaction is determined. The results are compared with the exchange reaction of cadmium mesoporphyrin and cadmium protoporphyrin with cobalt acetate in acetonitrile. Substituents in the 2,4-positions of cadmium complexes of protoporphyrins are shown to influence the rate of the metal-exchange reaction. The increasing order of the rates of the metal-exchange reaction between protoporphyrins and cobalt chloride in acetonitrile is established.     

Chemische Vitamin D<Subscript>3</Subscript>-Bestimmung in Lebertran

The different aspects of Vitamin D₃ determination and the data reported in the literature are discussed. The spectrophotometric determination of Vitamin D₃ in cod-liver oil is carried out after the alkaline saponification, extraction of unsaponified parts, precipitation of accompanying sterols and the column- and thin-layer chromatographic purification and separation of vitamin D₃ on 40 cm plates from other vitamins. The dyestuff α-naphtholbenzein is suited well as standard substance for the better location and identification of vitamin D₃ zone on the thin-layer plate. The results obtained from the chemical method were checked through the simultaneous biological determination.     

Mono- and diboronates derived from tridentate ONO ligands and arylboronic acids

The syntheses of eight [4.3.0] heterobicyclic boronates containing a N → B coordinative bond are described. The monomeric compounds were prepared by reaction of arylboronic acids with a tridentate ligand having the ONO donor set of atoms. It was shown that substituents at the para-position of the B-phenyl moiety transmit electronic effects to the CN bond which in turn is polarized by formation of the N → B coordination bond. At the same time, related tridentate ligands were also reacted with 1,4-benzenediboronic acid in order to prepare benzene diboron complexes. The structure of this type of compounds was confirmed by X-ray analysis for one of the derivatives.     

Dynamic and structural models of pyrimidine in the lowest excited singlet state

Problems on the normal vibrations of pyrimidine in the ground and excited states are solved. The matrices of rotation and shift of normal coordinates due to electronic excitation and Franck-Condon integrals are calculated. The vibronic spectra of pyrimidine are interpreted. Based on this interpretation, bond lengths and bond angles in the electronically excited first singlet state of the molecule are calculated: C₁C₂ 1.388 å, C₂N₃ 1.366 å, N₃C₄ 1.352 å, C-H 1.099 å; C₆C₁C₂ 105.5?, N₃C₄N₅ 127.8?, H₂C₂N₃ 110.1?.     

Coordination of N-Substituted Porphyrins with Simple and Chelate Zinc Salts in DMSO

The effect of peripheral substitution in the porphyrin macrocycle (₂OEtP, H₂TPP) of the nature of the N-substituent (X = Me, Ph) and of the anion in the salt solvate (A = ^–, NO₃ ^–, ^–) on the complexation of the N-substituted porphyrins with zinc salts in DMSO is studied. The positions of the bands in the electronic absorption spectrum of the (A)M(N-X)P metal complex were found to depend only slightly on the nature of the A anion in the composition of the coordination sphere of the complex. An inhibition of coordination of the N-substituted ₂TPP derivatives by zinc nitrate was discovered that is not typical of porphyrins proper. The type of hybridization of the substituted nitrogen atom in the porphyrin molecule is discussed. A mixed type of hybridization is suggested: the sp ²- and p ³-forms in the ligands and an almost complete transition to the p ³ form in the N-substituted metal complexes.     

Alternative methods for titratable acidity determination

Methods for determination of titratable acidity, other than traditional titration, i.e. methods without titration, are considered. A number of them use analytical acid-base reagents which quickly convert a mixture of strong and weak acids into a new system. This conversion makes it possible to obtain directly the analytical signal (pH, optical density, etc.) for titratable acidity calculation. These methods in stationary conditions and in flow injection analysis are discussed. Methods not using acid-base reagent (iodide-iodate, chromatographic, spectroscopic and others) are also described. The advantages of the alternative methods such as the decrease labour-consumption and analysis time, simplicity of automation and others are shown.     

A Spectropotentiometric Study of Association Equilibria of Cationic Acids of Mesoporphyrin IX Dimethyl Ester with Iodide Ions in Acetonitrile

The association equilibrium of porphyrinium ions of mesoporphyrin IX dimethyl ester (H₂MP) with iodide ions in acetonitrile was studied by spectropotentiometric titration. Two associates were revealed: (H₄MP^{2 +})(I^-) and (H₄MP^{2 +})(I^-)₂; the electronic absorption spectra of these species were measured, and their formation constants were determined.