Том 59, № 3 (2018)

(U)PBE0/cc-pVDZ method is used to study the structure of C₆₀Cl₃₀, C₆₀(OH)₃₀ molecules and Fe@C₆₀(OH)₃₀ endocomplex. The triplet state of the endocomplex is shown to be the lowest in energy among its four states corresponding to different spin multiplicities and positions of Fe nucleus within the fullerene cavity. This state is characterized by bonding between the iron atom and one of two benzenoid cycles of the carbon cage, six internuclear Fe–C distances (208 pm), and 1s²2s²2p⁶3s²3p⁶3d^7.24s^0.14p^0.3 electron configuration of iron with spin population of 2.36.

The electronic properties, such as binding energy, magnetic property, charge transfer, ionization potential, and electron affinity, of Ni_n–1Al (n = 2-20) neutral and ionic clusters are studied using the density functional theory calculations with the PBE exchange-correlation energy functional. The calculated total magnetic moments and ionization potential can decrease and increase with the addition of the Al atom, respectively. The calculated electron affinity has occurred with no significant change, except the Ni₁₆Al cluster.

In this work, the tautomeric transformations of a 1,5-dimethyl-6-thioxo-1,3,5-triazinane-2,4-dione molecule are explored at the M062X/6-311G(d,p) level of theory in gas and solution phases. These calculations show that the 1,5-dimethyl-6-thioxo-1,3,5-triazinane-2,4-dione isomer is more stable than its tautomer (4-hydroxy-1,5-dimethyl-6-thioxo-5,6-dihydro-1,3,5-triazin-2(1H)-one) in gas and solution phases. The frontier molecular orbitals and band gap energy calculations are performed at the M062X/6-311G(d,p) level in gas and various solvents. Solvent effects are analyzed using the self-consistent reaction field method based on the polarizable continuum model in chloroform, chlorobenzene, tetrahydrofurane, dichloromethane, and quinoline. The solvent effect on the N–H and C=O vibrations is explored. Also, natural bond orbital (NBO) analysis was used to understand the structure and bonding of the molecule.

¹H, ¹⁹F, ³¹P NMR, DSC, and XRD methods are used to study ionic mobility and structural transformations in the CsSbF₃(H₂PO₄) compound (I). Radical changes in ¹H, ¹⁹F, ³¹P NMR spectra above 390 K are associated with a crystalline disordered phase which forms in I at 400–420 K. This phase demonstrates high ionic mobility and further transforms (above 425 K) into the amorphous (glassy) phase. We have determined the types of ionic mobility in this compound and in its amorphous product. According to the NMR data, the diffusion in the proton sublattice of the disordered and amorphous phases proceeds even at room temperature.

AzaPCs containing tetra- and octaguaiacol moieties have not been investigated up to now. In this study, an unusual method is used for the synthesis of metalloAzaPCs (M: Zn, Co, Cu) containing guaiacol moieties. All compounds are characterized by a combination of FT-IR, ¹H NMR, ¹³C NMR, mass and UV/vis spectroscopy techniques. The molecular structure of starting pyrazine compounds 1 and 2 is also determined by the single crystal X-ray diffraction technique. The aggregation behavior of new Zn(II) AzaPCs is investigated in DMSO at different concentrations. The fluorescence properties of Zn(II) AzaPCs are investigated in different solvents. The fluorescence quantum yields of Zn(II) AzaPCs are calculated in DMSO.

With a tridentate Schiff base ligand N′-(2-hydroxy-3,5-di-tert-butylbenzylidene)-4-methylbenzohydrazide (H₂L) and MoO₂(acac)₂, an oxidomolybdenum(VI) complex is prepared and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. The complex crystallizes in the monoclinic space group C2/c with unit cell dimensions a = 20.187(2) Å, b = 7.9094(8) Å, c = 33.233(3) Å, β = 97.394(2)°, V = 5262.1(9) ų, Z = 8, R₁ = 0.0491, and wR₂ = 0.1322. The single crystal X-ray diffraction analysis reveals that the Mo atom is coordinated by NOO donor atoms of the Schiff base ligand, the methanol O atom, and two oxo groups in an octahedral coordination. Catalytic oxidation of the complex on some olefins is performed.

Based on the analytical expressions for permittivity ε₁(ω) and dielectric loss ε₂(ω) are obtained by the kinetic equation method, the frequency spectra of these coefficients are analyzed for an aqueous KF solution in a wide variation range of the density ρ, the concentration C, and the temperature T. With a certain choice of the solution model, the potential interaction energy Φab(|r|), and the radial distribution function g_ab(|r|) of a- and b-type ions, ε₁(ω) and ε₂(ω) of an aqueous KF solution are numerically calculated depending on ρ, C, T, and ω.

New fluoridozirconate with the nonstoichiometric composition Cs_1+x(H₂O)_1–xMgZr₂F_11+x·2H₂O (x ≈ 0.73) (I) is synthesized, its structure is determined, and the thermal behavior is analyzed. In the structure a part of F atoms is split over two positions which results in the formation of two types of coordination polyhedra around the Zr atom: Hoard dodecahedron ZrF₈ and pentagonal bipyramid ZrF₇. There are also two types of combining Zr polyhedra into chains: by sharing edges and by sharing edges and vertices. MgF₄(H₂O)₂ octahedra link infinite zirconium chains into layers. Between the layers cesium cations are located together with H₂O molecules statistically replacing a part of cesium cations. Dehydration of I occurs in the temperature range 140–400 °C and is complicated by the process of its partial pyrohydrolysis.

Compounds Y₂SiO₄Q (Q = S, Se) are obtained by the interaction of oxides and elemental substances in cesium chloride flux. The structures of these compounds are determined by the single crystal XRD analysis. These compounds isostructural and crystallize in the space group Pbcm with the following parameters: Y₂SiO₄S (I) a = 6.0462(8) Å, b = 6.8976(9) Å, c = 10.6558(13) Å, V = 444.39(10) ų; Y₂SiO₄Se (II) a = 5.9935(7) Å, b = 6.9216(8) Å, c = 10.7688(12) Å, V = 446.74(9) ų. The measured fluxing points are 1650±15 °С for I and 1850±15 °С for II.

The structure of levofloxacinium 2-thiobarbiturate trihydrate LevoH₂⁺Htba^–·3H₂O (I) (LevoH is levofloxacin, H₂tba is 2-thiobarbituric acid) is determined (CIF file CCDC No. 1547466); its thermal decomposition and IR spectrum are studied. The crystals of I are triclinic: a = 8.670(1) Å, b = 9.605(1) Å, c = 15.786(2) Å, α = 89.144(5)°, β = 88.279(5)°, γ = 76.068(5)°, V = 1275.4(3) ų, space group P1, Z = 2. The unit cell of I contains two LevoH₂⁺ ions, two Htba^– ions, and six H₂O molecules. The absolute structure of the crystal and the configuration of the chiral center in a levofloxacin molecule S are determined. Experiments for generating the second optical harmonics gave a positive result. Intermolecular hydrogen bonds (HBs) N–H···O and O–H···O in I form a bilayer system along the ab diagonal with hydrophilic moieties within a layer and hydrophobic moieties directed outward. The structure is stabilized by multiple HBs and the π–π interaction between the Htba–and LevoH₂⁺ ions and between the LevoH₂⁺ ions.

A change in the coordination of the copper atom in the crystal structure of [CuEn₃]CrO₄ (En is ethylenediamine) in studied in the range 150–300 K. According to the single crystal X-ray diffraction (XRD) data at 150 K, the single crystal has a complicated twining character based on the triclinic cell (a = 9.027(2) Å, b = 13.335(3) Å, c = 13.339(3) Å, α = 71.77(3)°, β = 70.53(3)°, γ = 70.42(3)°) composed of two crystallographically independent [CuEn₃]²⁺ complex cations. The coordination of copper atoms is a distorted square bipyramid; four short Cu–N distances lie in the range 2.049-2.082 Å; two long ones are 2.415 Å and 2.470 Å. According to the differential scanning calorimetry (DSC) data, near 218 K there is a phase transition. The single crystal XRD experiment performed at 250 K (a = 15.6992(19) Å, c = 9.7573(13) Å, V = 2082.6(6) ų, space group P\(\bar 3\)c1 (No. 165), Z = 6) shows that chromate anions are disordered over three positions about the с axis, and Cu–N distances are 2.120-2.177 Å. According to the DSC data, on further heating the structure undergoes yet another two alterations (260 K and 270 K) due to the disordering of oxygen atoms of chromate anions and the subsequent equalization of Cu–N distances. At 300 K in the structure (a = 9.0778(6) Å, c = 9.7715(5) Å, V = 697.4 ų, space group P\(\bar 3\)c (No. 163), Z = 2) all Cu–N distances are 2.155 Å, and chromate anions are disordered over six positions about the с axis. A comparative crystal chemical analysis of the packing of the studied structures is carried out.

A K[Ni(NH₃)₆]_2.5[Re₁₂CS₁₄(μ-O)₂(μ-SO₂)(CN)₆]·8H₂O compound (1) with a new [Re₁₂CS₁₄(μ-O)₂(μ-SO₂)(CN)₆]^6– cluster anion is prepared by the interaction of [Ni(NH₃)₆]_(aq)²⁺ with the products of incomplete substitution of μ-SO₂²⁻ ligands in the [Re₁₂CS₁₄(μ-SO₂)₃(CN)₆]^6– cluster anion and structurally characterized. New data on the effect of the ionic radius of the bridging μ-Q ligands on the geometric characteristics of the prismatic central {Re₃C(μ-Q)₃Re₃} unit of the bioctahedral cluster anions are obtained. The synthesis of compound 1 experimentally confirms the existence of stable intermediates in the μ-O^2– substitution reaction for the μ-SO₂²⁻ ligands of the [Re₁₂CS₁₄(μ-SO₂)₃(CN)₆]^6– anion and evidences that the reaction proceeds in steps.

Crystal structures of [Dy(dpm)₃]₂ (1) at 155(2) K (space group P2₁/n, a = 12.2191(3) Å, b = 27.6044(6) Å, с = 21.8615(5) Å, β = 105.172(1)°, V = 7116.9(3) ų, Z = 4) and Dy(dpm)₃ (2) at 200(2) K (space group Pmn2₁, a = 17.8741(7) Å, b = 10.5639(4) Å, с = 9.8336(4) Å, V = 1856.78(13) ų, Z = 2) are determined. The structure of complex 1 is similar to the previously known dimeric packings [Ln(dpm)₃]₂ (Ln = La, Pr, Nd, Eu, Gd, Tb). Complex 2 is isostructural to the previously studied molecular complexes Er(dpm)₃ and Lu(dpm)₃. At room temperature the luminescence quantum yield (QY) of Tb(dpm)₃ is found to reach 77% and that of Dy(dpm)₃ is 5%, while for the other Lu(dpm)₃ complexes, where Ln = Pr, Nd, Sm, Eu, Gd, Ho, Er, Tm, Yb, QY is below 1%. A series of [Tb(dpm)₃]₂ and Dy(dpm)₃ solid solutions is obtained by evaporating mixtures from solutions. Molecular films of these complexes on Si, Cu, Ni, Ti, KBr substrates are obtained by vacuum deposition.

By cross-coupling of 2-iodo-polyfluoroanilines with a [AuPPh₃NN] complex (where NN is 4,4,5,5- tetramethyl-3-oxide-1-oxyl-2-imidazolin-2-ide) in the presence of [Pd(PPh₃)₄], nitroxide radicals (2-aminopolyfluorophenyl- 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-3-oxide-1-oxyls) are synthesized. Their molecular and crystal structures are determined by the X-ray crystallographic analysis. It is shown that in the solid phase there are both intra- and intermolecular hydrogen bonds between NH₂ groups and O atoms of paramagnetic fragments, which link the molecules into chains or dimers.

Two new oxovanadium(V) complexes [VOLL¹] (1) and [VOLL²] (2) are prepared by the reaction of N′-(2-hydroxybenzylidene)pivalohydrazide (H₂L) and [VO(acac)₂] (where acac = acetylacetonate) with maltol (HL¹) and 8-hydroxyquinoline (HL²), respectively, in methanol. Crystal and molecular structures of the complexes are determined by elemental analysis, infrared and electronic spectra, ¹H NMR spectra, and single crystal X-ray diffraction. Complex 1 crystallizes in the monoclinic space group C2/c, with unit cell dimensions a = 15.828(2) Å, b = 22.412(3) Å, c = 12.873(3) Å, β = 121.256(5)°, V = 3903.7(12) ų, Z = 8, GOOF = 1.036, R₁ = 0.0554 and wR₂ = 0.1302. Complex 2 crystallizes in the monoclinic space group P2₁/n, with unit cell dimensions a = 11.995(2) Å, b = 8.700(2) Å, c = 19.466(3) Å, β = 96.497(3)°, V = 2018.3(6) ų, Z = 4, GOOF = 1.004, R₁ = 0.0449 and wR₂ = 0.0937. The V atoms are in the octahedral coordination.

Results of chemical kinetic/thermodynamic and spectroscopic studies of the reaction of cobalt(II) 5,10,15,20-(tetra-4-tert-butylphenyl)-21Н,23Н-porphyrin (Co^IITBPP) with 1-methyl-2-(pyridin-4′-yl)-3,4- fullero[60]pyrrolidine (PyF) in toluene at 298 K, ending by the formation of donor-acceptor triad (PyF)₂Co^IITBPP, are presented. Kinetic and thermodynamic parameters of the two-way formation reaction of the triad are obtained. The chemical structure of the obtained porphyrin-fullerene triad is identified by UV, visible, fluorescent, IR, and ¹H NMR spectroscopic techniques. The results are relevant for the problems of searching for supramolecular systems capable of photoinduced charge separation.

A novel zinc complex with the formula [Zn(hfac)₂(L¹)]_n (1) (L¹ = bis(4-(1H-imidazol-1-yl)phenyl)methanone) is synthesized and structurally characterized by IR, elemental analyses, and the single crystal X-ray diffraction analysis. The zinc(II) ions of 1 are in a distorted octahedral environment with four O atoms of the hfac ligands and two N atoms from two L¹ ligands. Each L¹ acts as a bridging ligand to link two Zn(II) atoms to form a helical chain.

The synthesis and characterization of two copper complexes, Cu(hfac)₂(L¹)₂ (1) and Cu(hfac)₂(L²)₂ (2) (L¹ = (E)-3-(4-(1H-benzo[d]imidazol-1-yl)phenyl)-1-([1,1′-biphenyl]-4-yl)prop-2-en-1-one, L² = (E)-3-(4-(1H-imidazol-1-yl)phenyl)-1-phenylprop-2-en-1-one) are reported. These complexes are characterized by elemental analyses, IR and single crystal X-ray diffraction analyses. The Cu(II) ions of 1 and 2 are both in a distorted octahedral environment with four O atoms of the hfac ligands and two N atoms from two L ligands. The supramolecular structures of 1 and 2 are stabilized by hydrogen bonds between the adjacent molecules. In addition, F···F interactions and π–π stacking interactions are also responsible for the stability of the structure in complex 2.

The synthesis of a novel Cu(I) complex with V-shaped bidentate ligands {[Cu(BIPMO)]×[CuBr₂]}_n where BIPMO = bis(4-(1H-imidazol-1-yl)phenyl)methanone is reported. It is characterized by IR spectroscopy, elemental analysis, and single crystal X-ray diffraction. Copper(I) ions in the complex are in a distorted environment in which donor atoms are provided by the bromide anion and nitrogen atoms of BIPMO ligands, respectively. Infinite anion chains formed by CuX₄ (X = Br or N) polyhedra are linked by BIPMO ligands to give rise to layers. Furthermore, the layers are linked into 3D networks through weak intermolecular interactions.