Diaqua[N,N-di(2-carboxyethyl)-o-anisidinato]copper(II) Dihydrate [Cu(o-Andp)(H2O)2] · 2H2O: Synthesis and Crystal Structure

Crystals of [Cu(o-Andp)(H₂O)₂] · 2H₂O (where o-Andp^2–is -anisidine-N,N-di-3-propionate) were synthesized and studied using X-ray diffraction analysis. The crystals are triclinic: a= 12.063(1) Å, b= 12.483(3) Å, c= 13.586(2) Å, = 91.29(1)°, = 111.67(1)°, = 104.00(1)°, V= 1830.5(5) ų, space group P , Z= 2, and R= 0.0528 for 5965 reflections with I2(I). The two crystallographically independent complexes are isostructural. The tetragonal–bipyramidal coordination of copper(III) involves three O atoms, the N atom of the tetradentate ligand o-Andp^2–, and two O atoms from water. The aminodipropionate group of the ligand (average Cu–O 1.939 Å and Cu–N 2.051 Å) and one of the coordinated water molecules (Cu–O(w) 1.991 Å) lie in the equatorial plane. The second water molecule (Cu–O(w) 2.32 Å) and the methoxy O atom of o-Andp^2–(Cu–O 2.37 Å) are in the apical positions of the bipyramid.     

Synthesis and properties of oxazolo[3,2-f]xanthines

Oxazolo[3,2-f]xanthines were synthesized by the reaction of 7-acylalkyl-8-bromo-3-methyl- and -1,3-dimethylxanthines with sodium benzoate in dimethylformamide. Their alkylation with methyl iodine was studied. The reaction of oxazolo[3,2-f]xanthines with primary amines leads to the previously described imidazo[1,2-f]xanthines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 534–537, April, 1988.     

Structure of 2,4,4,5,5‐pentamethyl‐2‐imidazoline‐1‐oxyl‐3‐oxide

The crystal and molecular structures of the stable nitroxide radical 2,4,4,5,5pentamethyl2imidazoline1oxyl3oxide was determined. The N—O bond lengths are 1.279(2) and 1.280(2), respectively. The O^-—N⁺=C—N— O fragment is nearly planar with carbon atoms of the ethyl fragment that deviated from the O—N⁺=C—N—O plane by –0.204(5) and +0.176(5). The minimum intermolecular distance between the oxygen atoms of NO groups is 4.094.     

Crystal structure of bis[2,2,5,5-tetramethyl-3-imidazoline-1-oxyl-4-(1′-propenyl-2′-oxyato)]nickel(II), Ni(C10H16N2O2)2

Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 2, pp. 112–117, March–April, 1992.     

Crystal structure of diaquabis(nitroamino-guanidine)nickel(II)perchlorate [Ni(CH5N5O2)2-(H2O)2](ClO4)2

Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 3, pp. 141–145, May–June, 1992.     

Chemical structure characteristics of lignins and their sorption capacity towards 4,15-diacetoxy-8-(3-methylbutyryloxy)-12,13-epoxytrichothecen-3-ol

Russian Chemical Bulletin - Chemical structure aspects of the lignins derived from various plants were investigated, and their adsorption capacity towards...     

Multinuclear compounds of s-elements with sterically hindered <Emphasis Type="Italic">о</Emphasis>-semiquinonates and catecholates

Alkali metals form mutinuclear compounds with redox-active singly and doubly reduced derivatives of sterically of hindered о-benzoquinones. Complexes [Na₆(Cat)₃(THF)₇]?4THF, [Na₅(Cat)₂(SQ)(THF)₅], [Na₄(SQ)₄(THF)₄]?THF?C₆H₁₄, [Na₄(3,5-SQ)₄(THF)₄], [K₄(SQ)₄(THF)₄]?4THF and [Li₃(SQ)₃(THF)₃]?THF (Cat is catecholate, SQ is semiquinonate) possessing high sensitivity to atmospheric oxygen were synthesized and their structures were determined. Magnetochemical measurements and quantum chemical calculations revealed that variation of the alkali metal and/or change in the structure of the polymetallic core significantly affect the energy of exchange interaction between the unpaired electrons of the paramagnetic ligands framing the polynuclear metal core formed by s-elements.     

Estimation of detection limits in electron probe X-ray microanalysis

Different local methods of analysis are estimated with the aim of revealing the possibility for determining the minimum concentrations of chemical elements. Among all examined approaches, electron probe X-ray microanalysis (EPMA) has been chosen as the most accurate and promising technique. The dependences between the elemental detection limit and the analyzer??s technical parameters are investigated. It has been ascertained that the experimentally determined detection limits of light elements are substantially higher than those of heavy elements. The reasons leading to the less efficient EPMA of light elements, as well as possible ways of elimination thereof, are discussed. It is demonstrated that an X-ray mirror can be used to reach the theoretically predicted detection limits of B, O, and C.