Structure and tunneling splitting spectra of methyl groups of tetramethylpyrazine in complexes with chloranilic and bromanilic acids.

The crystal and molecular structure of the 2,3,5,6-tetramethylpyrazine (TMP) complex with 2,5-dibromo-3,6-dihydroxy-p-quinone (bromanilic acid, BRA) has been studied and the results are compared with TMP CLA (2,5-dichloro-3,6-dihydroxy-p-quinone (chloranilic acid, CLA) complex. The X-ray structure of TMP BRA complex indicates the formation of dimeric units, in which two BRA(-) anions are connected by two O-H···O (2.646(2) Å) hydrogen bonds, whereas the cations and anions are joined together by strong N(+)-H···O(-) (2.

Effective catalytic disproportionation of aqueous H2O2 with di- and mono-nuclear manganese(II) complexes containing pyridine alcohol ligands.

The two novel manganese(II) complexes with 2-hydroxymethylpyridine (2-CH2OHpy) {[Mn2(μ-Cl)2(2-CH2OHpy)4]Cl2·2H2O (1)} and 2-hydroxyethylpyridine (2-(CH2)2OHpy) {[Mn(2-(CH2)2OHpy)2(NCS)2] (2)} were synthesized and characterized by means of X-ray diffraction, IR, EPR, HF EPR spectroscopy, magnetic and TG/DTG data. The complexes show catalase-like activity in neutral aqueous solution since they were able to disproportionate H2O2 to harmless H2O and O2. Both complexes act as true catalysts since they reverted to their original form after depleting all the H2O2, as suggested by the operando resonant inelastic X-ray spectroscopy (RIXS) measurements.

Assembling novel Cd(II) complexes with multidentate nitrogen donor ligands obtained in situ from the system: zerovalent copper, cadmium oxide, 1-hydroxymethyl-3,5-dimethylpyrazole and ammonium thiocyanate.

A novel 3D coordination polymer [Cd2(L(1))(2)(SCN)(4)(MeOH)(2)](n) (1) and monomeric [Cd(NCS)(2)L(2)] (2) (L(1) = urotropine, L(2) = tris(1-(3,5-dimethylpyrazolylmethyl))amine) have been prepared in a one-pot synthesis using 1-hydroxymethyl-3,5-dimethylpyrazole as the starting ligand. The most prominent feature is the formation in situ of the organic compounds: urotropine and scorpionate-tripodal ligands.

4,4'-, 5,5'-, and 6,6'-dimethyl-2,2'-bipyridyls: the structures, phase transitions, vibrations, and methyl group tunneling of their complexes with chloranilic acid.

The crystal and molecular structures of 4,4(')- and 6,6(')-dimethyl-2,2(')-bipyridyl complexes with 2,5-dichloro-3,6-dihydroxy-p-benzoquinone (chloranilic acid, CLA) have been determined and compared with those of the complex with the 5,5(')-derivative, which is known to possess interesting antiferroelectric properties. In the crystalline state, all three compounds form hydrogen bonded chains with N(+)-H···O(-) and O-H···N bridges on both sides of the bipyridyl constituent. The comparison of three derivatives indicates that the N(+)-H···O(-) hydrogen bonds are shortest for the 5,5(')-dimethyl complex.

The structure of diaminodurene and the dynamics of the methyl groups.

Diaminodurene crystallizes in the orthorhombic space group Pbca, with eight molecules in the unit cell. Four inequivalent methyl groups with different environments exist in a molecule. The amino groups are also different, which is well reflected in infrared spectra.

Synthesis and pharmacological screening of derivatives of isoxazolo[4,5-d]pyrimidine.

A number of derivatives of isoxazolo[4,5-d]pyrimidine were prepared with structures similar to that of purine. Condensation of the hydrazide of 4-amino-5-benzoylisoxazolo-3-carboxylic acid 2 with ethyloxalyl chloride followed by cyclization gave 3-oxdiazolo-[1,3,4]-4-amino-5-benzoylisoxazole 7 which, upon cyclization with acetonitrile followed by reactions with different amines, gave derivatives of isoxazolo[4,5-d]pyrimidine 9 and 10d-g. Compounds 8g and 10f were tested for their effects on the immune response in the mouse model.

[NHN]+ hydrogen bonding in protonated 1,8-bis(dimethylamino)-2,7-dimethoxynaphthalene. X-ray diffraction, infrared, and theoretical ab initio and DFT studies.

Structural (X-ray diffraction), infrared spectroscopic, and theoretical MP2 and DFT studies on the HBr and DBr adducts of 1,8-bis(dimethylamino)2,7-dimethoxynaphthalene ((CH3O)2.DMAN) were performed. This particular proton sponge has been chosen for its strong basicity and display of the buttressing effect influencing the hydrogen bond dynamics and properties.

Elastic, quasielastic, and inelastic neutron-scattering studies on the charge-transfer hexamethylbenzene-tetracyanoquinodimethane complex.

The 1:1 hexamethylbenzene (HMB)-tetracyanoquinodimethane (TCNQ) complex shows a first-order phase transition at 230/218 K (heating/cooling) with no change of the space group. The neutron-diffraction studies reveal that this transition is related to a freezing of the rotation of methyl groups. The results for 100 K enabled precise determination of configuration of HMB.

Structural, spectral, and magnetic properties of end-to-end di-mu-thiocyanato-bridged polymeric complexes of Ni(II) and Co(II). X-ray crystal structure of di-mu-thiocyanatobis(imidazole)nickel(II).

Thiocyanatonickel(II) and thiocyanatocobalt(II) complexes of the composition Ni(NCS)(2)(HIm)(2) (1) and Co(NCS)(2)(HIm)(2) (2), where HIm = imidazole, were prepared and studied. In particular, the crystal structure of Ni(NCS)(2)(HIm)(2) was determined by X-ray methods. This compound crystallizes in the monoclinic system, space group P2(1)/n, with a = 7.