Structure and magnetic properties of 2,4,6,8-tetra(<Emphasis Type="Italic">tert</Emphasis>-butyl)phenoxazin-1-one adducts with cobalt(II) salts

Complex formation reaction of redox-active 2,4,6,8-tetra(tert-butyl)phenoxazin-1-one with cobalt(II) chloride leading to the dimeric adduct has been studied. UV spectroscopy studies have revealed the equilibrium of the formed adduct with dissociated form of the complex in the acetonitrile solution. In the presence of ethylene glycol, the complex formation with cobalt(II) perchlorate has afforded the high-spin trimolecular adduct. Crystal structure of the obtained adducts has been studied by means of X-ray diffraction analysis.     

Role of inner- and outer-sphere bonding in the sensitization of EuIII-luminescence deciphered by combined analysis of experimental electron density distribution function and photophysical data

A series of lanthanide adducts with different amounts of 1,10-phenanthroline, chloride ions, and water molecules in the inner and outer coordination spheres are investigated with the aim of relating the chemical bonding patternin the crystals to the luminescence properties of the Eu ion: [LnCl1Phen2(H2O)3]Cl2(H2O) (Ln ) Eu, 1Eu; Gd, 1Gd;Tb, 1Tb), [EuCl2Phen2(H2O)2]Cl1(H2O) (2), and [EuCl2Phen1(H2O)4]Cl1(H2O) (3). The influence of inner- versus outersphere ligands on the Ln-X bond lengths and angles in the structure is examined. A detailed topological analysis of the electron density function derived from the X-ray diffraction data for 1Gd is performed within the frame of the"atoms in molecule" theory for the first time for a lanthanide complex. The chemical bonding pattern is interpreted in terms of net atomic charges, bond energies, and electron transfers from the ligands to the metal ion. A noteworthy finding is that the energy of extended noncovalent interactions occurring in the second coordination sphere (H-bonding and pi-stacking interactions) is comparable to that of Ln-ligand bonds. The luminescence properties of the three Eu adducts are interpreted with the results of electron density distribution function topology. An intraligand charge transfer state is identified, and its contribution in the ligand-to-europium energy transfer process is analyzed.The outcome of this study is that specific interionic interactions which are usually not considered in theoretical calculations or in the interpretation of luminescence properties play an important role in the sensitization of the Eu luminescence.     

Anion-anion assembly in crystal of sodium nitroprusside

The experimental charge density in the crystal of disodium pentacyanonitrosoferrate (sodium nitroprusside) dihydrate was analyzed in detail by means of Bader's atoms in molecules theory. It was shown that nitroprusside anion is involved in relatively strong self-interactions through the nitroso group. The obtained results agree well with the spectroscopic data, indicating the tendency of the corresponding moiety to the formation of anion-anion association both in solutions and in the crystalline phase.     

Laser induced gratings in CdS

The diffraction from laser-induced gratings is observed in CdS at low temperature in the spectral region of the absorption edge. The excitation intensity is varied from about 100 W/cm² to 1 MW/cm². The reasons for the formation of gratings are a broadening of the excitonic absorption band, a new resonance due to two polariton transitions to the biexciton and the formation of an electron-hole plasma with increasing excitation intensities.     

Synthesis,structure, and magnetic properties of a Yb<Superscript>III</Superscript> complex with the iminopyridine radical-anionic ligand

The reaction of equimolar amounts of ytterbocene (C₅Me₄H)₂Yb(THF)₂ and iminopyridine 2,6-Prⁱ₂C₆H₃N=CH(C₅H₄N) accompanied by the one-electron oxidation of the ytterbium ion produced the unique lanthanide complex (C₅Me₄H)₂Yb^III[2,6-Prⁱ₂-C₆H₃NCH(C₅H₄N)]–? with the iminopyridine radical-anionic ligand. The structure of the complex in the crystalline state was established by X-ray diffraction and its magnetic properties were studied in the temperature range of 1.8—300 K.     

Synthesis and structure of nickel and copper chelate complexes with coumarin azo ligand

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Acylation of phosphoryl- and thiophosphorylacetonitriles under phase transfer catalysis conditions and the keto-enol tautomerism of phosphorus-substituted acylacetonitriles

A procedure was developed for acylation of phosphoryl- and thiophosphorylacetonitriles under phase transfer catalysis conditions. The reaction in the solid KOH/MeCN system affordedC-acylation products in high yields. In the individual state and in aprotic solvents, these products exist in the enol form (Z isomers) stabilizedvia a strong intramolecular hydrogen bond. In hydroxyl-containing media and in aprotic bipolar solvents, these compounds exist as a mixture of two geometric isomers (E andZ) of the corresponding enols. In this case, theZ isomer exists in two forms, namely, in the cyclic form with an intramolecular hydrogen bond and in the open form stabilized by intermolecular hydrogen bonds with the solvent. The results of X-ray diffraction analysis of both forms ofZ isomers of the compounds containing the phosphoryl and thiophosphoryl groups are discussed. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1687–1694, September, 1998.     

Features of chemical bonding within the Fe(NO)<Subscript>2</Subscript> fragment for crystalline bis(thiosulfate) tetranitrosyl diiron tetramethylammonium salt as an example according to high-resolution X-ray diffraction data

Results of the study of the experimental charge density function for a crystal of the watersoluble {(СH₃)₄N+}₂[Fe₂(S₂O₃)₂(NO)₄] iron complex are presented. An inequality of two NO ligands at the same metal atom follows from the results of topological analysis of the charge density reconstructed particularly by using the “invariom” model. The inequality also reproduces that in the earlier studied complex Fe(SC₂H₃N₃)(SC₂H₂N₃)(NO)₂]?0.5H₂O, which is not caused by a superposition of spin states. Crystal packing analysis demonstrates the absence of a significant influence of solvation effects on the observed features of chemical bonding in the Fe(NO)₂ fragment.     

Synthesis and antihypotensive properties of 2-amino-2-thiazoline analogues with enhanced lipophilicity

In a search of nitric oxide synthase inhibitors with prolonged vasoconstrictive activity, a series of lipophilic cyclohexafused 2-amino-2-thiazolines was obtained via cyclization of tert-butyl- or benzoyl-substituted N-(cyclohex-2-en-1-yl)thioureas. The crystal structure of intermediate N-[(3aRS,7aSR)- 3a,4,5,6,7,7a-hexahydro-1,3-benzothiazol-2-yl]benzamide hydrobromide was determined by X-ray analysis. One compound was found to cause pronounced and prolonged vasoconstrictive effect after single injection to the Wystar rats with lipopolysaccharide induced acute endotoxic (vasodilatation) shock.     

Total synthesis of diaeudesmin and epieudesmin enantiomers from diallyl

Russian Chemical Bulletin - A total synthesis of both pairs of enantiomers of natural lignans, diaeudesmin and epieudesmin, was described. The synthesis involved enantioselective allylborylation of...