Proton-deuterium exchange of acetone catalyzed in imidazolium-based ionic liquid-DO mixtures.

The reaction of the proton-deuterium exchange of acetone in imidazolium-based ionic liquid (IL)-deuterium oxide mixtures was studied in detail NMR spectroscopy. Certain ILs exhibit considerable catalytic properties and contribute to the course of reaction up to the complete deuteration. The efficiency of deuterium exchange crucially depends on the features of ILs; the type of anion and chain length of cation.

Crystal structure of 2-(1,3,7,9-tetra-methyl-2,4,6,8-tetra-oxo-1,2,3,4,6,7,8,9-octa-hydro-pyrido[2,3-d:6,5-d']dipyrimidin-5-yl)benzamide di-methyl-formamide hemisolvate.

The title compound, C20H18N6O5·0.5C3H7NO, crystallized as a di-methyl-formamide (DMF) solvate. In the main mol-ecule, the dihedral angle between the pyridodi-pyrimidine fused-ring system and the benzamide substituent is 82.

Crystal structure, thermal and spectral studies and growth of nonlinear optical L-lysinium fluoride crystal.

In current study properties of L-lysinium fluoride (L-Lys⋅HF) are determined by X-ray diffraction, infrared and Raman spectroscopy, SHG and by UV-vis transmittance spectrum measurement. L-Lys⋅HF (C6H15FN2O2), crystallizes in a monoclinic system with space group P21, a=5.464(1)Å, b=7.

Tracking reactive intermediates by FTIR monitoring of reactions in low-temperature sublimed solids: nitric oxide disproportionation mediated by ruthenium(II) carbonyl porphyrin Ru(TPP)(CO).

Interaction of NO ((15)NO) with amorphous layers of Ru(II) carbonyl porphyrin (Ru(TPP)(CO), TPP(2-) = meso-tetraphenylporphyrinato dianion) was monitored by FTIR spectroscopy from 80 K to room temperature. An intermediate spectrally characterized at very low temperatures (110 K) with ν(CO) at 2001 cm(-1) and ν(NO) at 1810 cm(-1) (1777 cm(-1) for (15)NO isotopomer) was readily assigned to the mixed carbonyl-nitrosyl complex Ru(TPP)(CO)(NO), which is the logical precursor to CO labilization. Remarkably, Ru(TPP)-mediated disproportionation of NO is seen even at 110 K, an indication of how facile this reaction is.

Nitrosyl isomerism in amorphous Mn(TPP)(NO) solids.

Reaction of NO with amorphous Mn(TPP) layers gives two Mn(TPP)(NO) isomers with linear and bent Mn-N-O geometries that reversibly interconvert with changes in temperature. DFT computations predict that the linear complex is the singlet ground state while the bent structure is a triplet state.

[(4-Dimethyl-amino-2-methyl-5-phenyl-furan-3-yl)meth-yl]diethyl-methyl-aza-nium iodide.

In the title compound, C(19)H(29)N(2)O(+)·I(-), the dihedral angle between the mean planes of the essentially planar furan (r.m.s.

Six-coordinate nitrosyl and nitro complexes of meso-tetratolylporphyrinatocobalt with trans sulfur-donor ligands.

By Fourier transform infrared and optical spectroscopy, it has been observed that interactions of dimethyl sulfide and tetrahydrothiophene with nitrosyl and nitro complexes of meso-tetra-p-tolylporphyrinatocobalt [Co(TTP)] lead to the formation of previously unknown six-coordinate species. Nitrosyl complexes of the general formula (S-donor)Co(TTP)(NO) are thermally unstable and can be seen only at low temperatures both in the solid state and in solution. The nitro complexes (S-donor)Co(TTP)(NO(2)) are fairly stable at room temperature in the solid state but partly decompose upon dissolution.

Comment on "Growth and characterization of glycine picrate single crystal" by T. Uma Devi et al. [Spectrochim. Acta A71 (2008) 340-343].

The crystal grown and characterized in the title paper in reality is diglycine picrate.

Electric field effects on one-bond indirect spin-spin coupling constants and possible biomolecular perspectives.

Electric field (EF) induced changes of one-bond indirect spin-spin coupling constants are investigated on a wide range of molecules including peptide models. EFs were both externally applied and internally calculated without external EF application by the hybrid density functional theory method. Reliable agreement with experimental data has been obtained for calculated one-bond J-couplings.

Potassium l-2-nitrimino-1,3-diazepane-4-carboxyl-ate monohydrate.

The title compound, K(+)·C(6)H(9)N(4)O(4) (-)·H(2)O, crystallizes with the K atoms located on special positions related by pseudocentres of symmetry. Each K atom is coordinated by six O-atom donors. The N and water H atoms are involved in inter- and intra-molecular N-H⋯O, N-H⋯N and O-H⋯O hydrogen bonding.

l-Argininium ethyl sulfate.

The title compound, C(6)H(15)N(4)O(2) (+)·C(2)H(5)O(4)S(-), exhibits nonlinear optical properties. An extensive hydrogen-bonding network [N⋯O = 2.786 (4)-3.

Six-coordinate nitrato complexes of iron(III) porphyrins.

The interaction of tetrahydrofuran (THF) with thin films of the nitrato complexes Fe(III)(Por)(eta(2)-O(2)NO) [Por = meso-tetraphenylporphyrinato (TPP) and meso-tetratolylporphyrinato (TTP) dianion] at low temperature leads to the formation of the six-coordinate nitrato complex Fe(Por)(THF)(NO(3)), which was characterized by IR and UV-visible spectroscopies. Formation of the THF adduct was accompanied by nitrate linkage isomerization from bidentate to monodentate coordination. The iron(III) center remains in a high spin state in contrast with the previously observed low-spin nitratonitrosyl complex Fe(TPP)(NO)(eta(10-ONO(2)).

Dielectric permittivity and temperature effects on spin-spin couplings studied on acetonitrile.

Dielectric permittivity (epsilon) and temperature effects on indirect spin-spin coupling constants were studied using acetonitrile as a probe molecule. Experiments were accompanied by hybrid DFT (density functional theory) studies, where the solvent was modeled using the polarization continuum model. Owing to its numerous types of J-couplings, acetonitrile is a very convenient molecule against which various basis sets can be tested or the best basis set can be selected for a given study.

Torsion sensitivity in NMR of aligned molecules: study on various substituted biphenyls.

To estimate the torsion sensitivity of dipolar coupling, biphenylic molecules were chosen as probes due to their relatively simple structure and the surprisingly high ambiguity of the only flexible parameter-the interring torsion angle. Solution structures of 4,4'-dibromobiphenyl and 4,4'-diiodobiphenyl are reported for the first time in two liquid crystals I52 and ZLI 1695. The comparison of NMR structures of various para-substituted biphenyls (BPs), calculated by the additive potential maximum entropy (APME) approach, shows that the small spread of torsion angle values in case of different solvents and para-substituents is in good agreement with theoretical expectations from hybrid density functional theory (DFT) methods.

Assessment of solvent effects: do weak alignment media affect the structure of the solute?

Alignment media used for measuring residual dipolar couplings, such as solutions of filamentous phages, phospholipid mixtures, polyacrylamide gels and various lyotropic liquid crystalline systems were investigated with respect to solvent effects on molecular structure. Structural parameters of the small rigid model compound 13C-acetonitrile were calculated from dipolar couplings and variations from expectation values were used for assessment of solvent effects. Only minor solvent effects were observed for most of the media employed and the measured structural data are in good agreement with microwave data and theoretical predictions.

Quantitative description of the tilt of distorted octahedra in ABX3 structures.

A description of the tilt of octahedra in ABX(3) perovskite-related structures is proposed that can be used to extract the unique values for the tilt parameters varphi, theta and delta of ABX(3) structures with regular and distorted octahedra up to the point symmetry \bar 1, from atomic coordinates and lattice parameters. The geometry of the BX(6) octahedron is described by three B-X bond lengths (r(1), r(2), r(3)) and three X-B-X bond angles (psi(12), psi(13) and psi(23)) or alternatively by a local strain tensor together with an average B-X bond length. Connections between the proposed method and Glazer's tilt system are discussed.

Low-temperature spectral observation of the first six-coordinate nitrosyl complexes of cobalt(II) meso-tetratolylporphyrin with trans nitrogen base ligands.

Low-temperature interaction of nitrogen base ligands with layered Co(TTP)(NO) (TTP = meso-tetratolylporphyrinato dianion) as well as its toluene solution leads to the formation of the first six-coordinate species of the general formula (B)Co(TTP)(NO) (where B = piperidine and pyridine). The nu(NO) stretching bands of these species appear at lower frequencies compared with the five-coordinate nitrosyl derivative and depend on the nature of the trans axial ligand. The equilibrium constants and enthalpies of formation of these new species are determined.

Twinning and structure of Eu(0.6)Sr(0.4)MnO3.

The crystal structure of europium strontium manganese trioxide, Eu(0.6)Sr(0.4)MnO3, has been refined using a multiply twinned single crystal containing six twin components.

1,2,5-Substituted derivatives of 2-phenylpyrrolidine.

The structures of the potential anti-human-immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase inhibitors (NNRTI) 1-tert-butoxycarbonyl-2-phenylpyrrolidine-2-carboxylic acid, C(16)H(21)NO(4), (I), and 2-ammoniomethyl-1-benzyl-5-oxo-2-phenylpyrrolidine chloride, C(18)H(21)N(2)O(+).Cl(-), (II), have been investigated by X-ray diffraction. The investigations confirm a butterfly-like conformation for both compounds.