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Salt Na2[OsCl6] is obtained by the interaction of H2[OsCl6]·H2O with NaCl in boiling concentrated hydrochloric acid. According to the single crystal X-ray diffraction data, the substance crystallizes in the cubic system, space group Fm3m, a = 9.7461(11) A, V= 925.8(3) A3, Z = 4, R1= 0.029, wR2 = 0.070. The compound is characterized by UV-vis and IR spectroscopy.

A novel complex with the stoichiometry [(NH2)2CSSC(NH2)2]2[OsIVCl6]Cl2·3H2O (1) is isolated as a product of the reaction of H2[OsCl6] with thiourea in concentrated HCl under deliberately optimized conditions favoring a partial thiourea oxidation to α,α′-dithiobisformamidinium dication but preserving hexachloroosmate [OsCl6]2- anions. A bromide analogue [(NH2)2CSSC(NH2)2]2[OsIVBr6]Br2·3H2O 2 is afforded by a similar reaction. A counter synthesis of 1 is accomplished via the direct ion-exchange reaction between H2[OsCl6] and [S2C2(NH2)4]Cl2. Crystal structures of 1 and 2 are unambiguously established by synchrotron radiation-based single-crystal X-ray diffraction at 100 K. The two compounds are isostructural and are crystallized in the orthorhombic space group Cmcm, Z = 4. Unit cell parameters are for 1: a = 11.279(2) A, b = 13.611(3) A, c = 16.731(3) A; for 2: a = 11.695(2) A, b = 14.005(3) A, c = 17.015(3) A. The osmium atoms in [OsX6]2− (X = Cl or Br) anions adopt slightly distorted octahedral coordination. The α,α′-dithiobisformamidinium cations are paired into rings via the NH…Cl− hydrogen bonds. The rings are further linked into a spatial network by H-bonds with water molecules and S…Cl nonvalence interactions.

New heterocyclic quinolizidine systems were prepared from (1R,5S,12S)-tetrahydrocytisine. The synthetic scheme included arylation of tetrahydrocytisine by 2-fluoro-5-nitrobenzaldehyde and condensation of the resulting aldehyde with 1,3-dimethylbarbituric acid. The Knoevenagel intermediate obtained from the condensation was cyclized by a T-reaction to give two spirocyclic products as a derivative with the lupanine skeleton and its regioisomer with the 11,15-diazapentacyclo[11.7.1.02,11.05,10.015,20]heneicosane skeleton. The cyclization occurred highly stereoselectively. The structures of the products were proven using NMR and X-ray crystal structure analyses.

In this paper, synthesis of 4 phenol-titanium (IV) complexes (phenol: Salicylate, 3,4-Dihydroxy-3-cyclobutene-1,2-dione, Pyridine-2,3-diol and Catechol) were studied, then synthesizing TiO2 by the controlling thermal decomposition of the obtained complexes was studied at low temperature. The pure TiO2 nanoparticles were obtained when the complexes were heat-treated at different temperatures based on their ligands. Characterization of the complexes was carried out by FT-IR spectroscopy within 400–4000 cm−1, UV-Vis spectroscopy in 200–800 nm range, the method of atomic emission with inductively coupled plasma and the micro-method for analyzing a metal and CHN analysis, respectively. Quantum-chemical model of the titanium – phenol complexes was also studied to determine the structure and spectral properties of the isolated titanium complexes. Furthermore, thermal analysing was used to obtain DTA curves of TiO2 nanoparticle, X-ray diffraction (XRD) was analyzed to specify phase and size of TiO2, energy band gap of the nanoparticles were obtained by UV–Vis diffuse reflectance spectrometer, field emission scanning electron microscopy (FESEM) image accompanied EDAX analyzing were used to investigate morphology and types of the elements and their amount, respectively. According to the result, obtained TiO2 nanoparticles are beneficial to be used as catalysts to degrade harmful organic substances under UV light.

Novel osmium complexes (ThioH)2[OsCl6] (1) and (ThioH)2[OsBr6] (2) have been synthesized via the interaction of H2[OsX6] (X = Cl, Br) with thiourea (Thio) in concentrated HX and characterized by chemical analysis, potentiometry, IR- and UV–Vis spectroscopy, X-ray powder and single-crystal diffraction. UV–Vis spectroscopy of 1 and 2 in solutions supports the preservation of [OsX6]2− ions that however demonstrate considerable solvatochromism. The longer-wavelength bands experience a hypsochromic shift with respect to the crystalline state. Intense bands of Os-halogen vibrations in ATR IR spectra are red-shifted with respect to those for K2[OsX6]. The complexes are isostructural and crystallized in the triclinic space group P 1 ¯ , Z = 1. Unit cell parameters are for 1: a = 7.1800(14) A, b = 7.2700(15) A, c = 7.7800(16) A, α = 78.89(3)°, β = 87.83(3)°, γ = 65.11(3)°; for 2: a = 7.3169(15) A, b = 7.5504(15) A, c = 8.2065(16) A, α = 80.00(3)°, β = 88.55(3)°, γ = 63.37(3)°. The cations (NH2)2CSH+ and anions [OsX6]2− are assembled into two-tier layers by N–H…X and S–H…X hydrogen-bonds and S…X non-valent contacts.

X-ray diffraction is used to study complex [H(DMSO)2][OsBr4(DMSO)2] (1). The compound crystallizes in the triclinic crystal system, space group Pī, unit cell parameters are as follows: a = 8.5942(3) A, b = 8.7621(3) A, c = 16.0193(6) A, V = 1072.25(7) A3, α = 76.3740(10)°, β = 75.6060(10)°, γ = 68.3790(10)°, Z = 2, R = 0.0270.

New stereoselective methods for the chemical modification of cytisine based on T-reactions are reported. A reaction of cytisine with 2-chloro-5-nitrobenzaldehyde and followed condensation with 1,3-dimethylbarbituric acid affords N-(5-nitro-2-{1,3-dimethylperhydropyrimidine-2,4,6-trione-5-methynyl})cytisine, which undergoes a cyclization with the tetrahydropyridine ring closure. The cyclization proceeds via two competing routes yielding 5,5-spirobarbituric acid derivatives with 11,19-diaza-pentacyclo[11.7.1.02,11.05,10.014,19]henicosane and 11,15-diazapentacyclo-[11.7.1.02,11.05,10.015,20]henicosane skeletons. The cyclization reaction in solutions afford either 24.25-trans and 15,16-trans isomers or trans and cis isomer mixtures, depending on the specific solvent. Meanwhile, 24,25-cis and 15,16-cis isomers are formed stereoselectively under heterogeneous conditions in water suspensions. Trans-5,5-spirobarbiturates under similar conditions undergo isomerization into more stable cis-analogs by the configuration inversion at the C7 atom. The synthesized 5,5-spirobarbituric acid derivatives were successfully converted into alkaloid-like quinolizidine systems (1R,2R,3R,13S)-7-nitro-18-oxo-11,19-diazapentacyclo[11.7.1.02,11.05,10.014,19]henicosa-5(10),6,8,14,16-pentaene-3-carboxylic acid and (1R,2S,3S,13S)-nitro-16-oxo-11,15-diazapentacyclo[11,7,1.02,11,05,10,015,20]henicosa-5,7,9,17,19-pentaene-3-carboxylic acid and their derivatives via the spiropyrimidine moiety removal by the stereoselective hydrolysis. The molecular and crystal structures of the target substances were elucidated by X-ray crystallography and NMR.

The reactions of H2OsX6 · nH2O (X = Cl, Br) with dimethyl sulfoxide (DMSO) or DMSO-d6 in acetone afford the osmium(IV) complexes: [H(DMSO-O)2]2[OsCl6] (I), [H(DMSO-O)2]2[OsBr6] (II), [H(DMSO-d6)2]2[OsCl6] (Ia), and [H(DMSO-d6)2]2[OsBr6] (IIa). According to the X-ray diffraction data (CIF files CCDC 997574 (I) and 997575 (II)), the crystals of compounds I and II are isostructural, triclinic, space group \(P\bar 1\), a = 7.7732(2), b = 8.9209(3), c = 9.8176(3) A, α = 69.0120(10)°, β = 72.2170(10)°, γ = 67.4330(10)°, Z = 1 (I); a = 7.9241(4), b = 9.1701(5), c = 10.2644(5) A, α = 67.5250(10)°, β = 71.0670(10)°, γ = 66.5990(10)°, Z = 1 (II). The compounds consist of cations [H(DMSO)2]+ with a very strong hydrogen bond O⋯H⋯O (O⋯O 2.441 A in I and 2.457 A in II; the hydrogen atom is predominantly localized at one oxygen atom) and anions [OsX6]2−, being somewhat distorted octahedra. The synthesized complexes are characterized by IR spectroscopy, UV/Vis spectroscopy, NMR spectroscopy, and potentiometry. In DMSO solutions, cations [H(DMSO)2]+ dissociate and DMSO enters the internal sphere of the anions to form the DMSO complexes of osmium(III) and osmium(II).

Bromo dimethyl sulfoxide osmium(II) complexes were synthesized: trans-[OsBr2(dmso-S)4] (1) was obtained by the reaction of K2[OsBr6] with DMSO in the presence of SnBr2 at 100°C and cis,fac-[OsBr2(dmso-S)3(dmso-O)] (2) was prepared by thermal isomerization of 1 in a DMSO solution at 150°C. The coordination mode of DMSO molecules was determined by IR and 1H and 13C NMR spectroscopy. X-ray diffraction analysis showed that compound 2 crystallizes in the monoclinic system, space group P21/n; a = 8.4711(5) A, b = 27.7876(15) A, c = 8.5569(5) A, β = 115.7110(10)°; Z = 4. The coordination polyhedron of osmium is a distorted octahedron; the osmium environment is formed by two cis-arranged bromine atoms and three fac-S-coordinated and one O-coordinated DMSO molecules. The interconversion of complexes in solutions was studied by UV/Vis and 1H and 13C NMR spectroscopy. In chloroform and DMSO, complex 2 isomerizes to cis-[OsBr2(dmso-S)4] and (in the light) to 1. The complexes trans-[OsX2(dmso-d6)4], where X = Cl, Br, were isolated from DMSO-d 6 and characterized by the IR spectra.

The reaction of H2[OsBr6] with DMSO in ethanol solution resulted in DMSO complex [H(dmso-O)2][OsIII(dmso-S)2Br4] (1) described previously as an intermediate product in the reaction of K2[OsBr6] with DMSO and characterized by EAS and ESR spectra. The coordination of DMSO molecules was established by IR and 1H and 13C NMR spectroscopy. The oxidation state of osmium and trans arrangement of DMSO molecules in the anion were established by ESR. The behavior of complex 1 in solutions was studied by EAS, ESR, and mass-spectrometry: a displacement of Br− ions accompanied by the reduction of osmium to oxidation state +2 occurs in DMSO, a solvation with displacement of DMSO molecules is observed at the first stage in water and methanol (rate constants 2.3 × 10−4 and 1.7 × 10−3 s−1, respectively), the sequential substitution of DMSO molecules and osmium oxidation to form [OsIVBr6]2− ions takes place in 4 mol/L HBr.