Five new binuclear iron(II) complexes have been synthesized and characterized, namely: [Fe₂(BTPHA)L₄](ClO₄)₂, where L stands for 4,4'-dimethyl-2,2'-bipyridine (Me₂-bpy); 2,9-dimethyl-1,10-phenanthroline (Me₂-phen); 5-bromo-1,10-phenanthroline (Br-phen); 5-chloro-1,10-phenanthroline (Cl-phen) and 5-methyl-1,10-phenanthroline (Me-phen), respectively, and BTPHA represents the tetrabromoterephthalate dianion. Based on the elemental analyses, molar conductance measurements, and spectroscopic studies, extended BTPHA-bridged structures consisting of two iron(II) ions, each in an octahedral environment are proposed for these complexes. The variable temperature magnetic susceptibilities (4~300 K) for [Fe₂(BTPHA)(Me₂-bpy)₄](ClO₄)₂ (1) and [Fe₂(BTPHA)(Me₂-phen)₄](ClO₄)₂ (2) complexes were measured and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, H = -2J S₁.S ₂ giving the exchange integrals J = -1.09 cm^-1 for (1) and J = -2.13 cm^-1 for (2). These results indicate the presence of a weak antiferromagnetic spin-exchange interaction between the metal ions within each molecule. The influence of the bromo substituents in the bridge ligand on the magnetic interactions between the metal ions in this kind of complexes is also discussed.

Distribution coefficients, D, of trace amounts of impurities (Mg²⁺, Co²⁺, Zn²⁺, Cd²⁺, Cu²⁺, Mn²⁺, Ca²⁺, Sr²⁺, Ba²⁺ and Pb²⁺) have been determined during crystallization of Ni(NO₃)₂^.6H₂O. Their dependencies on the ionic radii of M²⁺ ions, solubilities and structures of the corresponding nitrates as well as their abilities to form solid solutions with Ni(NO₃)₂^.6H₂O have been analyzed. The D values are comprised in the range 0.011(D_Sr)-0.40(D_Co) and depend neither on solubilities in water of corresponding nitrates nor similarity of their crystal structure.These coefficients generally decrease when the difference between ionic radii of macrocomponent and microcomponent becomes larger, but this dependence is disturbed by relatively high values of D_Co and D_Zn, resulting from the ability to form solid solutions Ni(Co)(NO₃)₂^.6H₂O and Ni(Zn)(NO₃)₂^.6H₂O. The solubility of macroamounts of cobalt(II) and zinc(II) nitrate hexahydrates in the solid phase (Ni(NO₃)₂^.6H₂O) is the main factor influencing their distribution coefficients.

Phase equilibria in Ag₂Se-In₂Se₃-GeSe₂ and Ag₂Se-In₂Se₃-SnSe₂ systems have been established using X-ray and microstructural analysis. Homogeneity region of the AgInSe₂ compound and lattice parameters of solid solutions in both systems have been determined. Four new compounds have been found. X-ray single crystal study has been performed for Ag₂In₂GeSe₆: space group Cc, a = 1.2692(3), b = 0.7492(1), c = 1.2644(3) nm, ß = 109.50(3)°.

Black-green dithallium(I) phthalocyanine complex with metallic conductivity has been obtained in crystalline form. The UV-VIS, IR, far IR and resonance Raman spectra of the Tl₂Pc complex are presented. The absorption electronic spectra indicate the proximity of the HOMO and LUMO of the Pc ligand in energy. The additional band at 516 nm is attributed to CT transition. The vibrational spectroscopic data of dithallium(I) phthalocyanine complex are discussed in terms of specific chemical bonds and atomic group and compared with the other phthalocyanines. An empirical vibrational assignment of the observed fundamentals is given.

The complexing properties of 1-propyl-2-methylimidazole (1-Pr-2-CH₃Im) and 1-propyl-2-imidazolecarboxaldehyde (1-Pr-2-CHOIm) with Co^II, Ni^II, Cu^II and Zn^II were investigated pH-metrically at 25°C and at the ionic strength of 0.5 mol dm^-3 (KNO_3<->). The stability constants calculated indicate the formation of complexes with metal:ligand ratio of 1:1, 1:2, 1:3 and 1:4. The stability of the metal complexes with both imidazoles depends mostly on the substituent situated between the nitrogen atoms of the imidazole ring. It was found that the carboxaldehyde oxygen atom participates in the formation of the coordination bond. The formation of the weak chelate copper(II)-1-propyl-2-imidazolecarboxaldehyde complexes was confirmed by EPR spectra. The electronic spectra reveal that the cobalt(II) forms both tetrahedral and octahedral species with 1-Pr-2-CH₃Im, but 1-Pr-2-CHOIm forms only six-coordinated compounds. The NMR spectra of 1-Pr-2-CHOIm indicate that hydration of the CHO takes place when Zn(II) ions are introduced into the ligand solution at pH 5.03.

Thermogravimetry (TG), differential thermal analysis (DTA), infrared (IR), electronic, EPR spectra and other analytical methods have been applied to the investigation of the thermal behaviour and structure of the compounds [Cu(ac)₂(mpc)]₂^.2CH₃OH (I), Cu(Clac)₂(mpc) (II), Cu(Cl₂ac)₂(mpc)₂ (III) and Cu(Cl₃ac)₂(mpc)₂ (IV) (where ac = CH₃COO^-, Clac = ClCH₂COO^-, Cl₂ac = Cl₂CHCOO^-, Cl₃ac = Cl₃CCOO^- and mpc = methyl-3-pyridyl carbamate). The solid phase intermediate and resultant products of thermolysis had been identified. The possible scheme of decomposition of the complexes is suggested with as a final product, CuO. IR data suggest a unidentate coordination of carboxylate to copper(II). Methyl-3-pyridyl carbamate was coordinated through nitrogen atom of its heterocyclic ring in complexes I-IV. EPR spectra suggest a dimeric structure of complex I and monomeric structure of complexes II-IV.

Determination of stability constants and calculation of distribution of complexes formed by Co(II), Ni(II) and Cu(II) with adenosine monophosphate (AMP) and cytidine monophosphate (CMP) were performed by using computer-aided analysis of potentiometric titration data. On the basis of a comparison of the protonation constants of free ligands and MHL-type complexes the proton localization in the coordination compounds was established. The coordination mode in complexes in solution as well as in solids was determined from the results of spectral as well as equilibrium studies. Formation of macrochelate complexes and the occurrence of coordination dichotomy of the N(1)/N(7) type as well as N(1)/N(7)/O (phosphate group) was evidenced. Contrary to the similar complexes with Cu(II) and Co(II), the phosphate group of the nucleotide becomes essentially involved in the interactions with Ni(II) ions only at high pH values. The modes of coordination in aqueous solution and solid complexes are compared.

The reaction of 4,4-dimethyl-1,3-thiazole-5(4H)-thiones 7a-c with dimethyl 2-diazo-3-(phenylamino)butanoate (2), prepared from dimethyl fumarate and phenyl azide, in toluene at 80°C yielded mixtures of dimethyl 2-(4,5-dihydro-4,4-dimethyl-1,3-thiazol-5-ylidene)-3-(N-phenylamino)butanedioates of type 11 and four diastereoisomeric 4,4-dimethyl-9-phenyl-1,6-dithia-3,9-diazaspiro[4.4]non-2-ene-7,8-dicarboxylates of type 12. The formation of the products of type 12 is rationalized by a novel cyclization of intermediate thiocarbonyl ylides 9. The structures of cis-12a, cis-12c, and trans-12c were established by X-ray crystallography.

Ambident anion derived from phosphorothioselenoates was glycosylated with 1,2,3,4-tetra-O-acetyl--D-xylopyranose in the presence of boron trifluoride etherate to yield Se-xylosyl and S-xylosyl phosphorothioselenoates. Structures of the products were established on the basis of selective oxidation, ³¹P NMR, ¹H NOE studies and unambiguously by X-ray diffraction.

The cathodic hydrogen evolution reaction on cobalt electrode in pure molten triethylammonium tetrafluoroborate has been studied using ac impedance and polarization curves methods. The data consist of Tafel slopes, exchange current densities, the apparent heat of activation and the double layer capacitance.

The reduction of Vitamin K₃ bisulfite (VK₃B) in the presence of -cyclodextrin (-CD) has been investigated by Osteryoung square wave voltammetry (OSWV) in phosphate buffer (pH = 6.6). The results showed that -CD forms a 1:1 inclusion complex with VK₃B. The dissociation constant was calculated from the plot of I_pc² vs. (I_pc(VK3B)²- I_pc²)/[-CD] to be K_d = 3.5×10^-3 M. The diffusion coefficients of VK₃B and the inclusion complex were obtained by chronocoulometry (CC) to be D_f = 1.5×10^-6 cm²/s and D_c = 0.7×10^-6 cm²/s, respectively. UV-visible spectra gave further evidence of the complex formation and the dissociation constant obtained by spectroscopy, K_di = 5.0×10^-3 M, is in good agreement with that determined by electrochemistry.

Superacid properties of alumina, silica-alumina and silica exposed to TiCl₄ and HfCl₄ vapour have been studied and compared with previously obtained results for catalysts containing BF₃, SbF₅, AlCl₃ and ZrCl₄. It was found that the reaction of the vapour of metal halides of Lewis nature (MeX_n) with oxides like alumina, silica-aluminas and silica results in the formation of the Br<148>nsted superacid centres if acid strength of hypothetical acid MeX_{n^.XH is higher than that of sulphuric one. The Lewis superacid centres are formed in the reaction of carrier containing alumina phase with metal halide of strong electron acceptor ability.}

Periodic (up to period 8) and chaotic oscillations observed during anodic dissolution of copper on rotating disc electrode (RDE) in a copper sulphate-sulphuric acid solution under potentiostatic conditions are described and analyzed. Limit cycles and strange attractors are reconstructed. The Poincarr sections and 1D return maps are presented and discussed.

The differential capacitance characteristics of Hg/0.1 mol dm^-3 KF and Hg/0.1 mol dm^-3 LiClO₄ interfaces were studied in the presence of L-histidine (His). The strongest adsorption of His on the mercury electrode was observed in solutions at pH 8. Probably, it results from the strong interactions between mercury and His molecules possessing in these solutions one or two deprotonated nitrogen atoms in the imidazole ring. Quantitative analysis of the data was possible for the alkaline solutions only. The anomalies observed in the course of C-E curves in the neutral or acidic solutions are discussed. Adsorption of His on a free surface is very weak. Practically it results from the salting-out effect, because, in the case of the solution without the electrolyte, the His molecules do not adsorb at this interface.

The crystal structure of Bi₂S₃ both natural (bismuthinite) and synthetic, reported in the literature, was determined at ambient temperature in the non-polar space group Pbnm. Physical properties of Bi₂S₃ indicate, however, on the possible phase transitions both in the high and low temperature regions. Precise lattice parameters measured as a function of temperature have shown weak anomalies at 160 and 410 K. The phase transition above 400 K has been also confirmed by measurements of microwave dielectric permittivity along the c-axis. The crystal structure of Bi₂S₃ has been determined at 130, 295 and 460 K. At all three temperatures the crystal structure was successfully refined in the space group Pbnm. The weak phase transitions observed in Bi₂S₃ apparently do not change the symmetry, or these changes are too small to be detected at the present level of accuracy of the X-ray crystal structure determination.

The title steroid crystallizes in the monoclinic P2₁ space group with unit cell dimensions: a = 11.745(2) , b = 10.564(2) , c = 12.979(3) , ß= 95.73(3)°. Its crystal and molecular structure was determined by X-ray diffraction methods. The A ring has a symmetrical chair conformation. The B ring has a half-chair conformation, with asymmetry parameter C₂^{5 , 6} = 0.6°. The C ring has an intermediate sofa-half-chair conformation with asymmetry parameters: C₂⁹⁶ = 2.3°, C₂¹¹ = 5.8°, C₂^9,11 = 4.8°, and C₂^8,96 = 5.6°. The D ring adopts an envelope conformation with asymmetry parameter C₂¹³ = 10.7°. The cholesterol side chain adopts a fully extended conformation with torsion angles -170.6(6)°, 167.9(6)°, -171.9(6)° and 175.6(7)°, i.e. it belongs to the most populated conformer A, and with the terminal C26 and C27 methyl groups in gauche, trans conformations.