X-ray diffraction study of Rb<Subscript>2</Subscript>[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(CrO<Subscript>4</Subscript>)<Subscript>3</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>] · 4H<Subscript>2</Subscript>O

The compound Rb₂[(UO₂)₂(CrO₄)₃(H₂O)₂] · 4H₂O was studied by X-ray diffraction. The crystals are monoclinic, a = 10.695(2) Å, b = 14.684(3) Å, c = 14.125(3) Å, β = 108.396(4)°, sp. gr. P2₁/c, Z = 4, V = 2104.9(7) ų, and R = 0.0491. The main structural units are layers consisting of [(UO₂)₂(CrO₄)₃(H₂O)₂]^2? anions belonging to the crystal-chemical group A ₂ T ₂ ³ B ²M ₂ ¹ (A = UL ₂ ²⁺ , T ³ and B ² are CrO ₄ ^2? , and M ¹ is H₂O) of uranyl complexes. The uranium-containing layered groups are held together by electrostatic interactions with rubidium cations, as well as by hydrogen bonds with the participation of inner- and outer-sphere water molecules.     

Synthesis and crystal structure of Na4[Er2(EDTA)2(μ2-C2O4)] · 8H2O (where EDTA stands for ethylenediamine-N,N′-tetraacetate)

Synthesis was carried out, and structure solved for the new dinuclear erbium(III) complex having a composition of Na₄[Er₂(EDTA)₂(C₂O₄)] · 8H₂O (where EDTA stands for ethylenediamine-N,N′-tetraacetate). The compound was characterized by IR and UV spectroscopy, mass spectrometry, and X-ray crystallography. In the structure of the compound, erbium(III) has C.N. 8 and a coordination polyhedron shaped as a square antiprism. The EDTA and oxalate ions manifest their characteristic coordination modes: N,O-chelate hexadentate and bridge-cyclic tetradentate, respectively.     

Nucleophilic sulfanylation of 1,5-disubstituted pent-2-en-4-yn-1-ones

Regioselectivity of nucleophilic addition of benzenethiols and phenylmethanethiol to 1,5-diarylpent-2-en-4-yn-1-ones in ethanol in the presence of triethylamine at 0–30°C is determined by the nucleophile nature. Phenylmethanethiol adds to the double bond, whereas benzenethiols add to the triple bond. The addition products, 1,5-diaryl-3-benzylsulfanylpent-4-yn-1-ones and 1,5-diaryl-5-(4-arylsulfanyl)penta-2,4-dien-1-ones, respectively, were isolated in 43–89% yield. Substituents in the aryl rings of the substrates did not affect the reaction direction.     

Formation of the second superhydrophobic shell around an encapsulated metal ion: synthesis, X-ray structure and electrochemical study of the clathrochelate and bis-clathrochelate iron(II) and cobalt(II, III) dioximates with ribbed perfluoroarylsulfide substituents

The nucleophilic substitution of six chlorine atoms of the n-butylboron-capped clathrochelate iron and cobalt(II) precursors with perfluoroarylthiolate anions afforded the hexaperfluoroarylsulfide macrobicyclic iron and cobalt(II) tris-dioximates. The complexes obtained are soluble in aromatic and aliphatic hydrocarbons as well as in polar aprotonic solvents due to the presence of the superhydrophobic fluorine-containing molecular periphery. As it follows from the X-ray data for five iron and cobalt mono- and bis-clathrochelates, the geometry of their macrobicyclic frameworks is affected by both the nature of an encapsulated metal ion and that of the ribbed substituents. Bis-capping fragment Co(II)O(6) of the Co(III)Co(II)Co(III) bis-clathrochelate possesses a trigonal antiprismatic geometry, all the Co(II)N(6) coordination polyhedra are trigonal-prismatic, and those of the encapsulated iron(II) and cobalt(III) ions are intermediate between them. The wide range of Co-N distances as well as the significant shifts of the encapsulated cobalt(II) ions from the centres of their N(6)-coordination polyhedra were explained by the Jahn-Teller distortion. The EPR and magnetometry data are also characteristic of the low-spin cobalt(II) complexes with this distortion. The parameters of the (57)Fe M?ssbauer spectra of the iron macrobicycles are characteristic of the low-spin iron(II) complexes. The cyclic voltammograms (CVs) for the complexes studied contain the one-electron oxidation and reduction waves assigned to metal-centered redox-processes. The Fe(2+/3+) and Co(2+/3+) oxidations are quasi-reversible or irreversible. The anionic clathrochelate species resulting from the reversible Co(2+/+) reductions are stable on the CV time scale, whereas their iron(I)-containing analogs are unstable.     

Synthesis and structure of [UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>){CONH<Subscript>2</Subscript>N(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>}<Subscript>2</Subscript>]

The single crystals of [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] were synthesized and studied by X-ray diffraction. The crystals are monoclinic, a = 7.461(2) Å, b = 8.828(2) Å, c = 11.756(2) Å, β = 107.21(3)°, space group Pc, Z = 2, R = 2.94%. The structure comprises infinite chains [UO₂(C₂O₄){CONH₂N(CH₃)₂}₂] extended along [001] and corresponding to the AT¹¹M ₂ ¹ crystallochemical group (A = UO ₂ ²⁺ , T¹¹ = C₂O ₄ ^2? , M¹ = N,N-CONH₂N(CH₃)₂) of uranyl complexes. The chains are connected into a three-dimensional framework by hydrogen bonds involving the oxygen atoms of oxalate and uranyl ions and the N,N-dimethylcarbamide methyl groups.     

Benzene complex [(η-9-SMe2-7,8-C2B9H10)Fe(η-C6H6)]+ as a synthon for the cationic ferracarborane moiety

The photochemical reaction of [(η⁵-C₆H₇)Fe(η-C₆H₆)]⁺ (1) with the [(η-9-SMe₂-7,8-C₂B₉H₁₀)]⁻ anion followed by the treatment of the resulting ferracarborane (η-9-SMe₂-7,8-C₂B₉H₁₀)Fe(η⁵-C₆H₇) (2) with hydrochloric acid afforded the benzene complex [(η-9-SMe₂-7,8-C₂B₉H₁₀)Fe(η-C₆H₆)]⁺ (3). The reaction of cation 3 with Bu^tNC produced the isonitrile complex [(η-9-SMe₂-7,8-C₂B₉H₁₀)Fe(^tBuNC)₃]⁺ (4). The structure of the complex [4]PF₆ was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2046–2048, October, 2007.     

Coordination polyhedra LnCl n (Ln = La-Lu) in crystal structures

The Voronoi-Dirichlet polyhedra (VDP) and the method of intersecting spheres were used to analyze 125 compounds containing 182 crystallographically nonequivalent sorts of LnCl _n complexes (Ln = La-Lu). The lanthanum C.N. varies from 6 to 10; eight sorts of coordination polyhedra are encountered in the structures, the Ln-Cl bond lengths in which can vary by 0.1–0.8 Å, depending on the C.N.(Ln). Despite the great diversity of C.N. and large scatter of bond lengths, the volume of the VDP was found to depend only on the nature of the Ln atom and its valence state     

The SmO n Coordination Polyhedra in Crystal Structures

Crystal-chemical analysis of all compounds studied to date and containing SmO _n coordination polyhedra was performed using the methods of Voronoi–Dirichlet polyhedra (VDP) and intersecting spheres. It was shown that the coordination number (CN) of Sm(III) atoms with respect to oxygen varies from 4 to 12 and the CN of Sm(II) is 5, 7, or 9. The Sm(III) Sm(II) transition was found to entail an increase in the VDP volume by, on average, 2.8 ų, whereas for a constant oxidation state of Sm, the VDP volume barely depends on the CN, although the Sm–O interatomic distances vary by 0.83 Å for Sm(III)-containing crystals and by 0.39 Å for Sm(II)-containing crystals. The results of analysis of the topology of [Sm _a O _b ] groups in the crystal structure are presented.     

New type of 2-alkyl-substituted 1,8-naphthyridine systems containing a phosphoryl group in the side chain

First organophosphorus derivatives of 2-alkyl-and 2,3-alkylene-substituted 1,8-naphthyridines were synthesized by the Friedländer reaction starting from 2-aminonicotinaldehyde and diphenylphosphoryl(cyclo)alkanones, respectively.     

Coordination Polyhedra LnO<Subscript><Emphasis Type="Italic">n</Emphasis></Subscript> (Ln = Tb,Dy, Ho) in Crystal Structures

The Voronoi-Dirichlet polyhedra (VDP) were used to study the stereochemical features of terbium, dysprosium, and holmium surrounded by oxygen in the structures of 456 compounds. The Tb, Dy, and Ho atoms have C.N.s of 6 to 12 with respect to oxygen. The volume of the VDP of lanthanide atoms does not depend on their C.N. or the shape of the coordination polyhedron, although the Ln(III)-O bond length changes by 0.6–0.7 Å. The Tb(III) → Tb(IV) transition is accompanied by a decrease in the terbium VDP volume by ～2 ų.