Complexes of Some Pyrido[1,2-a]pyrimidinium Perchlorates with Scandium,Yttrium, and Lanthanum. Crystal and Molecular Structure of 3-Chloro-9-Hydroxy-2,4-Dimethylpyrido[1,2-a]pyrimidinium Perchlorate

Complexes of scandium, yttrium, and lanthanum nitrates with 3-chloro-9-hydroxy-2,4-dimethylpyrido[1,2-a]pyrimidinium perchlorate (HL¹ClO₄) and 9-hydroxy-2,4-dimethylpyrido[1,2-a]pyrimidinium perchlorate (HL²ClO₄) were obtained. Their composition was formulated as Sc(LClO₄)₂(NO₃) and M(LClO₄)₂(NO₃)₂ (L = L¹ or L²; M = Y or La); structures for the complexes obtained were proposed. The crystal and molecular structure of HL¹ClO₄ was determined. Dissociation and complexation of HL¹ClO₄ and HL²ClO₄ in aqueous ethanol were studied using the spectroscopic method. Ligand dissociation and complexation constants were calculated. It was shown that a chlorine-containing organic ligand only slightly changes the composition and stability of the metal complexes.     

Nanostructuring in the process of the formation of mixed-anion compounds: Rare-earth borogermanates, germanophosphates, and borotungstates

Specific features of the textures (the preferred orientation of the nanometer building blocks) in the structures of mixed-anion compounds—rare-earth borogermanates, germanophosphates, and borotungstates that arise from the acid-base interaction in the Ln₂O₃-B₂O₃-GeO₂, Ln₂O₃-GeO₂-P₂O₅, and Ln₂O₃-B₂O₃-WO₃ systems (Ln = La-Gd)—have been studied. Based on characteristic texture traits, the mixed-anion compounds of early rare-earth elements can be divided into three groups: (i) Ln₂O₃: E_xO_y > 1, (ii) Ln₂O₃: E_xO_y = 1, and (iii) Ln₂O₃: E_xO_y < 1. Because of the dominant structural effect of the basic oxide Ln₂O₃ in the compounds of the first group, the structures of Nd₁₄O₈(BO₃)₆(GeO₄)₂ and Pr₁₁O₁₀(GeO₄)(PO₄)₃ are composed of infinite [LnO_n] bands and layers and discrete groups [EO_m] located in the interband and interlayer spaces. The dominant structural effect of the acid oxides [E_xO_y] in the compounds of the third group leads to the appearance of ring textures composed of [LnO_n], as well as to the appearance of chains and networks composed of [EO_m], in the structures of Ln(BGeO₅) and Ln(BO₂)(WO₄). Original Russian Text ￠ G.A. Bandurkin, N.N. Chudinova, G.V. Lysanova, K.K. Palkina, E.V. Murashcva, V.A. Krut’ko, G.M. Balagina, 2006, published in Zhurnal Neorganicheskoi Khimii, 2006, Vol. 51, No. 2, pp. 334–347.     

Synthesis and crystal structure of phosphate Ba<Subscript>1.5</Subscript>Fe<Subscript>2</Subscript>(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>

Double phosphate Ba_1.5Fe₂(PO₄)₃ was synthesized and structurally studied. Single crystals were synthesized by the fusion method. Cubic crystals, Z = 4, space group P2₁3, a = 9.866(1) Å. This structure is built of polyhedrons of four types: PO₄ tetrahedrons, two virtually regular FeO₆ octahedrons, BaO₁₂ twelve-vertex polyhedrons, and BaO₉ nine-vertex polyhedrons. These polyhedrons share common oxygen vertices to form three-dimensional [Fe₂(PO₄)₃]_3∞ framework containing barium atoms in cavities.     

Physicochemical properties of solutions of bis(2,3,5,6-tetraoxo-4-nitropyridinate) dianions. Crystal structures of sodium 2,3,5,6-tetraoxo-4-nitropyridinate trihydrate and sodium ammonium bis(2,3,5,6-tetraoxo-4-nitropyridinate) monohydrate

Ammonium 2,3,5,6-tetraoxo-4-nitropyridinate was shown to exist as stable dimers and act as a weak electrolyte in both a crystalline state and aqueous solutions. In a strongly alkaline medium, ammonium cations were successively replaced by sodium cations. The molecular and crystal structures of sodium 2,3,5,6-tetraoxo-4-nitropyridinate trihydrate and sodium ammonium bis(2,3,5,6-tetraoxo-4-nitropyridinate) monohydrate were established, and their spectroscopic characteristics were determined.     

Bis(1-amino-4-azafluoren-9-olium) and bis(2-amino-3-hydroxypyridinium) tetrachlorocobaltates(II): Crystal and molecular structure

Crystal and molecular structure and spectral characteristics are determined for bis(1-amino-4-azafluoren-9-olium) and bis(2-amino-3-hydroxypyridinium) tetrachlorocobaltates(II): CoCl₄(C₁₂H₁₁N₂O)₂ and CoCl₄(C₅H₇N₂O)₂, respectively. The structural units of the complexes are CoCl ₄ ^2? anions and organic cations protonated at the pyridine nitrogen atom.     

Modern technologies for detection and identification of explosive agents and devices

The physical principles and most effective modern technologies for detecting and identifying explosive agents and devices and the analytical potential of these technologies were considered to solve the problems of antiterrorist security and countermeasures against terrorist attacks using explosive devices based on explosive agents. Particular attention was paid to the possibility of detecting explosive agents and devices, in particular, during automated control at the entrance to airports, railway stations, and various institutions and organizations and security check of suspicious persons, luggage inspection, etc. An analysis of the possibilities for identifying explosive agents and devices can evidently create conditions for expanding the existing technologies or combining them with new technologies for detecting not only various types of explosives, but also narcotic drugs, firearms, cold weapons, radioactive substances, poisonous substances, highly toxic substances, biological agents, etc.     

Doppeloktaeder-Cluster [V2O9] in der Kristallstruktur von Vanadium(III)-diphosphat,V4(P2O7)3

Double-Octahedra Clusters [V₂O₉] in the Crystal Structure of Vanadium (III) Diphosphate, V₄(P₂O₇)₃ . As the first example for M^III diphosphates the crystal structure of V₄(P₂O₇)₃ (“ I ”) has been determined by means of X-ray diffraction of single crystals. I – according to [7] obtainable by thermal interaction of V₂O₅, H₃PO₃, and H₃PO₄ – crystallizes orthorhombically (data see above); in the unit cell two kinds of isolated doubleoctahedra (clusters) [V₂O₉], having the symmetry C_s, exist. Due to a mutual face-connection of the octahedra, within these clusters relatively short V–V distances are resulting: 2.774(8) and 3.026(7) Å. The diphosphate anions, O₃POPO₃^4? (three kinds; each having the symmetry C_s and staggered conformation), exhibit POP bond angles of 170°, being remarkably large for non-centrosymmetry. Because of the [M₂^IIIO₉] clusters in I , and also in the isostructural diphosphates Cr₄(P₂O₇)₃ and Fe₄(P₂O₇₃), magnetic investigations seem to be challenged.     

Growth and structure of ZnSnAs2 crystals

High-quality ZnSnAs₂ (I) single crystals have been grown. The unit cell parameters of compound I have been refined (a = b = 5.8360(1), c = 11.686(2) Å), and its crystal structure has been determined.     

Synthesis and crystal structure of the Ag(I) complex with a cyclic β-diketone, 2-(diphenylacetyl)indan-1,3-dione (L), and the HL molecule

An Ag(I) complex with HL (I), AgL (AgC₂₃H₁₅O₃, II), has been synthesized. Compounds I and II have been studied by X-ray diffraction. The crystals are monoclinic, I: space group P2₁/n, a = 10.459(2) Å, b = 12.354(2) Å, c = 13.390(3) Å, β = 96.67(3)°, Z = 4; II: space group P2₁/c, a = 10.764(2) Å, b = 10.683(2) Å, c = 15.939(3) Å, β = 101.57(3)°, Z = 4. The structural units of the crystal of I are neutral molecules with intramolecular hydrogen bonds. In structure II, the Ag₂O₆ dimeric groups and the ligands form infinite openwork layers perpendicular to the x axis and containing cavities. The layers are penetrated by channels with an oblong cross section. In the crystal of II, all intermolecular distances exceed the sums of the van der Waals radii of the corresponding atoms.