Mononuclear cobalt (III) complexes with <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-bromobenzylamine and <Emphasis Type="Italic">N</Emphasis>-salicylidene-2-hydroxy-5-chlorobenzylamine

Cobalt (III) complexes with N-salicylidene-2-hydroxy-5-bromobenzylamine (H₂sbba) and N-salicylidene-2-hydroxy-5-chlorobenzylamine (H₂scba), [n-(C₄H₉)₄N][Co(sbba)₂] (I) and [n-(C₄H₉)₄N][Co(scba)₂] (II), were synthesized. The crystal structure of II was determined by the single-crystal X-ray diffraction method at 90 K confirming its crystallization in the monoclinic space group P2₁/n with a = 11.729(2) Å, b = 16.901(3) Å, c = 21.483(4) Å, β = 98.840(4)°, V = 4208.2(14) ų, D_x = 1.295 g cm^?3, and Z = 4. The R1 [I > 2σ(I)] and wR2 (all data) values of 0.0664 and 0.1920, respectively, for all 9521 independent reflections. The compound is composed of a tetra(n-butyl)ammonium cation and an octahedral cobalt(III) complex anion with two scba^2? ligands in a meridional fashion. The electronic spectral features of I and II are consistent with the octahedral cobalt(III) ion with an N₂O₄ donor set.     

Stability of <Emphasis Type="Italic">s</Emphasis>-, <Emphasis Type="Italic">p</Emphasis>-, and <Emphasis Type="Italic">d</Emphasis>-element diphosphates in water

The mean atomic Gibbs energies of formation of (Δ _f ? _at ⁰ ) of s-, p-, and d-element diphosphates have been calculated using ion increments of the Gibbs energy (Δ _f G ⁰). The diphosphate hydrolysis kinetics is considered, and a correlation between the Δ _f ? _at ⁰ values and the hydrolysis rate constants is presented.     

Synthesis and structure of bis(1,2-diaminoethane) copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-hydroxybenzoate) monohydrate and <Emphasis Type="Italic">trans</Emphasis>-diaquabis(1,2-diaminoethane)copper(II) bis(<Emphasis Type="Italic">o</Emphasis>-aminobenzoate)

X-ray structural analysis has been performed for two complex compounds: Cu(en)₂(o-HB)₂H₂O (I) (a = 16.873(4) Å, b = 8.713(2) Å, c = 14.803(3) Å, β = 91.15(2)°, V = 2175.8(8) ų, C2/c, Z = 4, R(F) = 0.0263, 1516 reflections with I > 3σ (I)) and [Cu(en)₂(OH₂)₂]²⁺(o-AB^?)₂ (II) (a = 7.488(5) Å, b = 22.122(8) Å, c = 7.856(5) Å, β = 118.77(2)°, V = 1140.7(11) ų, P2₁/n, Z = 2, R(F) = 0.0432, 1684 reflections with I > 3σ(I)) synthesized under identical conditions (en is ethylenediamine, o-HB is o-hydroxybenzoate, and o-AB is o-aminobenzoate). Although the compounds were assumed to have similar structures and the Cu-Lig bond lengths and the cis and trans angles are acceptable for an octahedral structure, the geometric parameters of o-HB suggest that the copper atom has a plane square environment.     

Conducting materials prepared by the oxidation of <Emphasis Type="Italic">p</Emphasis>-phenylenediamine with <Emphasis Type="Italic">p</Emphasis>-benzoquinone

p-Phenylenediamine was oxidized with p-benzoquinone in the aqueous solutions of methanesulfonic acid (MSA). The conductivity of the products increased with increasing concentration of MSA from 1.5?×?10^?12 S cm^?1 in 0.1 M MSA up to 3.4?×?10^?4 S cm^?1 in 5 M MSA. The low-molecular-weight products are basically composed of one p-benzoquinone and two p-phenylenediamine molecules. Their molecular structure is discussed on the basis of mass, Fourier-transform infrared, Raman, NMR and electron paramagnetic resonance (EPR) spectroscopies. The formation of 2,5-di(p-phenylenediamine)-p-benzoquinone protonated with methanesulfonic acid best complies with the information provided by spectroscopic techniques. Its conversion to hydroquinone tautomer explains the formation of unpaired spins observed by EPR and their potential contribution to the conduction.     

Reactions of arylsulfinyl chlorides and <Emphasis Type="Italic">N</Emphasis>-(arylsulfonyl)arylsulfinimidoyl chlorides with <Emphasis Type="Italic">p</Emphasis>-aminophenols

In reactions of arylsulfinyl chlorides and N-(arylsulfonyl)arylsulfinimidoyl chlorides with p-aminophenols formed N-arylthio-1,4-benzoquinone imines, evidently through a stage of N-arylsulfinyl-4-aminophenols and N-(N-arylsulfonyl)arylsulfinylimidoyl-4-aminophenols that under the reaction conditions eliminate respectively H₂O and ArSO₂NH₂.     

Crystallographic and conformational analysis of (<Emphasis Type="Italic">E</Emphasis>)-2-isopropyl-4-(<Emphasis Type="Italic">p</Emphasis>-tolyldiazenyl)phenol

The molecular and crystal structures of the title compound, C₁₆H₁₈N₂O, were characterized and determined by single crystal X-ray diffraction method in addition to spectroscopic means such as IR, UV–VIS and ¹H NMR. The compound crystallizes in orthorhombic space group P bca, with a = 9.3350(5) Å, b = 23.4878(13) Å, c = 26.5871(12) Å, Z = 16, D _calc. = 1.1591(1) g/cm³, μ (MoK_α) = 0.073 mm^?1. Monomers of the compound in the crystal structure are linked into C(7) and C(8) chains generated by translation along the [1 0 0] direction with the aid of O–H···N type H-bonds which serve to the stabilization of periodic organization of the molecules beside major and minor component in the disordered azo fragment. In order to describe conformational flexibility and the crystal packing effects on the molecular conformation, potential barriers regarding the rotation along both Ar–N bonds were calculated by varying the related torsional degrees of freedom in every 10° ranging from ?180° to +180° via quantum chemical calculations at DFT/B3LYP level.     

Compositions and structures of nanoparticles of pentagonal axial symmetry <Emphasis Type="Italic">D</Emphasis><Subscript>5<Emphasis Type="Italic">d</Emphasis></Subscript>: Nanotubes

The method of determination of the structure and the number of atoms in the shells of nanoparticles as a function of the arrangement of atoms at the symmetry elements of a symmetry group has been developed. The formulas for the calculation of the number of particles with symmetry group D _5d are reported. The number of particles in these shells is determined by three structurally invariant numbers and the “quantum number” of the group order n. The classification of all possible nanostructures with symmetry group D _5d is given: C _θ+10z , z = 0, 1, 2, …, where the basic shells are C _θ = C ₂, C ₁₀, C ₁₂. The sum rule has been obtained for the coordination numbers of shell sites located at symmetry axes. Pentagonal axial nanoparticles are shown to be the initial shells for obtaining (5,5) and (10,10) armchair nanotubes or (5,0) and (10,0) zigzag nanotubes. The general formula of these nanotubes closed with icosahedral and dodecahedral caps is N _20+10p , N _60+10p (p = 1, 2, …). The graphical constructions of all classes of nanoparticles and nanotubes of the pentagonal axial type are reported.     

Synthesis of ethyl (2<Emphasis Type="Italic">E</Emphasis>,4<Emphasis Type="Italic">E</Emphasis>)- and (2<Emphasis Type="Italic">E</Emphasis>,4<Emphasis Type="Italic">Z</Emphasis>)-5-chloropenta-2,4-dienoates

An efficient synthetic approach to 2E,4E and 2E,4Z isomers of ethyl 5-chloropenta-2,4-dienoate has been developed on the basis of one-pot oxidation–olefination of readily accessible (E)- and (Z)-3-chloroprop-2-en-1-ols by the action of barium manganate and ethyl (triphenyl-λ⁵-phosphanylidene)acetate.     

Synthesis and biotests of 2-aryl-5-arylmethylidene-substituted 1,3-oxazol-5(4<Emphasis Type="Italic">H</Emphasis>)-ones and <Emphasis Type="Italic">N</Emphasis>-methyl-3,5-dihydro-4<Emphasis Type="Italic">H</Emphasis>-imidazol-4-ones as combretastatin A-4 analogs

A series of 2-aryl-5-arylmethylidene-1,3-oxazol-5(4H)-ones and 2-aryl-5-arylmethylidene-N-methyl-3,5-dihydro-4H-imidazol-4-ones was synthesized as structural analogs of combret- astatin A-4 (a compound possessing antitumor activity). (5Z)-5-[(4-Methoxyphenyl)methyl-idene]-3-methyl-2-(4-methylphenyl)-3,5-dihydro-4H-imidazol-4-one was found to exhibit the highest cytotoxicity against cells of human A549 lung carcinoma line (EC₅₀ = 6±0.8 μmol L^?1).     

Electrospray mass spectra of aqueous solutions of 4<Emphasis Type="Italic">f</Emphasis>-3<Emphasis Type="Italic">d</Emphasis> heterometallic chelates

The composition of aqueous solutions of the heterometallic chelates MLnDTPA and Ln₂M₃(EDTA)₃ (H₅DTPA = diethylenetriaminepentaacetic acid; H₄EDTA = ethylenediaminetetraacetic acid; Ln = Eu, La; M = Ni, Mn) and the monometallic chelates H₃Ni(DTPA), HNi₂(DTPA), H₂La(DTPA), and H₂Eu(DTPA) was studied by electrospray mass spectrometry (ESIMS). The mass spectra indicate that there is equilibrium between chelated rare-earth and 3d-metal ions in the aqueous solution of the heterometallic chelates. Both monometallic and bimetallic diethylenetriaminepentaacetates are observed for the 3d elements. The intensity ratio of the chelated rare-earth and 3d-metal ions in the aqueous solutions of the heterometallic complexes is in agreement with the ratio of the stability constants of the respective monometallic chelates.     

Crystal structure and luminescence of a terbium complex with <Emphasis Type="Italic">p</Emphasis>-methyl benzoate and 1,10-phenanthroline

A terbium p-methyl benzoate complex with 1,10-phenanthroline, [Tb(p-MBA)₃(Phen)]₂ (p-MBA = p-methyl benzoate and Phen = 1,10-phenanthroline), has been prepared and structurally characterized by X-ray diffraction. It crystallizes in triclinic system, space group P \(\bar 1\) with a = 12.8064(12), b = 13.3589(12), c = 19.8277(19) Å, α = 91.668(2)°, β = 97.775(2)°, γ = 106.312(2)°, C₇₂H₅₈N₄O₁₂Tb₂, M _r = 1489.06, V = 3217.6(5) ų, Z = 2, ρ _c = 1.537 g/cm³, μ(MoK _α) = 2.246 mm^?1, F(000) = 1488, the final R = 0.0622 and wR = 0.0962 for 14128 independent reflections with R _int = 0.0843. It consists of two types of crystallographically independent dimeric molecules [Tb(p-MBA)₃(Phen)]₂ noted as [Tb-1] and [Tb-2]. In the dimeric molecule [Tb-1], each Tb(III) is eight-coordinated with one Phen molecule, two bridging carboxylate groups, and two bidentate chelating carboxylate groups, while in [Tb-2] each Tb(III) is eight-coordinated with one Phen molecule, four bridging carboxylate groups, and one bidentate chelating carboxylate group. The title complex shows intense green luminescence under UV light at room temperature.     

Conformations and properties of <Emphasis Type="Italic">O</Emphasis>-Alkyl-<Emphasis Type="Italic">S</Emphasis>-(2-<Emphasis Type="Italic">N</Emphasis>,<Emphasis Type="Italic">N</Emphasis>-dialkylamino)-ethylmethylthiophosphonates

Conformers of the biologically active compounds CH₃P(O)(OR)(SCH₂CH₂NR ₂ ^′ ), where (I) R = i-C₄H₉, R′ = C₂H₅ and (II) R = C₂H₅, R′ = i-C₃H₇, are calculated within the AM1 level of theory. The elongated and twisted forms with maximum and minimum distances between a nitrogen atom and those of a phosphorus tetrahedron, respectively, and bearing a syn and anti oriented alkoxy group relative to a phosphoryl oxygen, are studied. It is found that the differences between the energy, electronic, and geometric parameters of these forms are apparent in differences between their properties, e.g., the ability to participate in complexation and protonation, reactions that to some extent simulate the interaction between a substance and a biological object.     

Molecular and crystal structure of a mixed-ligand cadmium complex with <Emphasis Type="Italic">p</Emphasis>-hydroxybenzoic acid and monoethanolamine

Single crystals of a mixed-ligand cadmium complex of the composition Cd(PHBA)₂(MEA) ₂ are grown from the solution of Cd(CH₃OO)₂, p-hydroxybenzoic acid (PHBA) and monoethanolamine (MEA) in aqueous ethanol. The crystallographic data are as follows: a = 11.6400(2) Å, b = 10.1363(1) Å, c = 16.6296(2) Å, β = 93.937(1)°, space group I2/a, V = 1957.44(5) ų, Z = 4. In the complex molecule located on the twofold axis, ligands of both types are bidentately bound to the cadmium ion having the coordination number 8. In the crystal structure, two H bonds of the O–H???O type combine complex molecules into layers parallel to the ab plane.     

Crystal and molecular structure of <Emphasis Type="Italic">tris</Emphasis>(<Emphasis Type="Italic">m</Emphasis>-chlorophenyl)phosphine selenide

The crystal and molecular structure of tris(m-chlorophenyl)phosphine selenide, C₁₈H₁₂Cl₃PSe (I), was investigated by X-ray diffraction (XRD) analysis. The trigonal rhombohedral structure of I (space group \(R\overline 3 c\), a = 14.110(2) Å, c = 32.360(4) Å, Z = 12) was solved by direct methods and refined by least squares in an anisotropic approximation (R = 0.029) for 1319 averaged measured reflections (CAD-4 automatic diffractometer, λCuK_α).     

Nickel catalysis for hydrogenation of <Emphasis Type="Italic">p</Emphasis>-dinitrobenzene to <Emphasis Type="Italic">p</Emphasis>-phenylenediamine

The activity of supported nickel catalysts (5–20% Ni) in the hydrogenation of p-dinitrobenzene to p-phenylenediamine was investigated. The catalysts were obtained by ureainduced precipitation. Activated carbon, alumina, titania, and silica gel were evaluated as supports. The most active catalysts, 5%Ni/TiO₂ and 20%Ni/SiO₂, provided 50–54% yields of p-phenylenediamine at complete dinitrobenzene conversion.     

5<Emphasis Type="Italic">p</Emphasis>-4<Emphasis Type="Italic">d</Emphasis> Emission spectrum with a cascade decay of the 3<Emphasis Type="Italic">d</Emphasis> vacancy in the Xe atom

The 5p-4d emission spectrum, obtained during cascade de-excitation of the initial deep 3d vacancy in the Xe atom, was calculated by directly constructing a decay tree in a stepwise manner. The cascade decay tree was constructed with allowance for all radiative and nonradiative channels of decay for the initial and all intermediate ionic configurations of the cascade. The probabilities of branching and transition energies were calculated in a one-electron approximation with averaging over configurations. The 5p-4d cascade emission spectrum has a complex structure with many components, which reflects the transitions from the wide variety of the many-hole intermediate configurations generated by the cascade. The calculated data agree well with the experiment.     

Binuclear copper(II) complexes with acyldihydrazones of <Emphasis Type="Italic">N</Emphasis>-benzenesulfonyl-<Emphasis Type="Italic">L</Emphasis>-aspartic acid

The structure and the EPR spectra of copper(II) coordination compounds with acyldihydrazones of N-benzenesulfonyl-L-aspartic acid and salicylaldehyde (2-hydroxyacetophenone) were described. The compounds were studied by chemical and thermal analyses, IR spectroscopy, and EPR. The molecular and crystal structures of copper(II) complexes with N-benzenesulfonyl-L-aspartic acid bis(salicylidene)hydrazone (H₄L¹) [Cu₂L¹ · 2Py] · 1.5 H₂O was determined by X-ray diffraction. The crystals are triclinic: a = 10.4714(4) Å, b = 12.9702(5) Å, c = 14.6187(9) Å, α = 104.763(2)°, β = 93.082(2)°, γ = 111.4240(10)°, space group P \(\bar 1\), Z = 2. The binuclear complexes containing copper cations whose coordination polyhedra are connected by an aliphatic spacer (Cu...Cu, 8.669 Å) are additionally linked by phenoxy bridges (Cu...Cu, 3.398 Å). The EPR spectra of these compounds in solutions exhibit an isotropic signal of seven HFS lines due to two equivalent copper ions with the spin Hamiltonian parameters g = 2.115?2.120, a _Cu = (35.5?38.0) × 10^?4 cm^?1, which is indicative of weak exchange interactions between the paramagnetic sites.     

Crystal Structure of <Emphasis Type="Italic">DL</Emphasis>-Valinium Tetrafluoroantimonate(III) Monohydrate

The crystal structure of an antimony(III) fluoride complex of the composition (C₅H₁₂NO₂)SbF₄·H₂O (I) involving a cation of α-amino isovaleric acid (DL-valine, Val) is determined. Crystals are monoclinic: a = 12.2024(2) Å, b = 6.1636(1) Å, c = 15.5167(3) Å, Z = 4, space group P2₁/c. The structure is formed of DL-valinium (C₅H₁₂NO₂)⁺ cations, complex [SbF₄]_n^n? anions having a polymeric chain structure, and crystallization water molecules. The [SbF₄]_n^n? complex anions consist of trigonal SbF4E bipyramids joined together by asymmetric bridging Sb–F(3)···Sb bonds. The structural units are organized into a threedimensional framework via N–H···F, N–H···O, and O–H···F hydrogen bonds.     

Synthesis and X-ray study of 6<Emphasis Type="Italic">H</Emphasis>-chromeno[3,4-<Emphasis Type="Italic">e</Emphasis>][1,3,4]triazolo[2,3-<Emphasis Type="Italic">a</Emphasis>]pyrimidine

2-Dimethylamino methylenechromanone 1 reacted with 4H-1,2,4-triazol-3-amine in acetic acid to give only one isolated product which was identified by X-ray study as 6H-chromeno[3,4-e][1,3,4]triazolo[2,3-a]-pyrimidine. The molecular structure of 3, C₁₂H₈N₄O, was determined to be monoclinic, P2₁/c, a = 16.3875(5), b = 8.8378(3), c = 13.8392(5) Å, β = 101.190(1)°, V = 1966.22(11) ų, Z = 8.     

Structure of hexaaquamagnesium (II) bis(4-<Emphasis Type="Italic">p</Emphasis>-aminobenzenesulfamido-2,6-dimethoxypyrimidinate) pentahydrate

The X-ray analysis of a single crystal of Mg(C₁₂H₁₃N₄O₄S)₂·11H₂O, where (C₁₂H₁₃N₄O₄S)^? is the anion of 4-p-aminobenzenesulfamido-2,6-dimethoxypyrimidine (sulfadimethoxine) is carried out. Unit cell parameters are: a = 19.753(4) Å, b = 34.031(7) Å, c = 13.859(3) Å; β = 125.37(3)°, C2/c, Z = 8, R(F) = 0.042. The structure is built of [Mg(OH₂)₆]²⁺, (C₁₂H₁₃N₄O₄S)^?, and water molecules and corresponds to the formula [Mg(OH₂)₆](C₁₂H₁₃N₄O₄S)₂·5H₂O. The IR bands of ν_asymSO₂ and ν_symSO₂ are bathochromically shifted as a result of their participation in hydrogen bonding, and not because of any direct coordination of sulfadimethoxinate anion to the complexing atom through oxygen.