M. A. Zakharov

SYNTHESIS AND CRYSTAL STRUCTURE OF COPPER(II) TRIFLUOROACETATES, CU2(CF3COO)4.2 CH3CN AND CU(CF3COO)2(H2O)4

Cu2(CF3COO)4 · 2 CH3CN (I) and Cu(CF3COO)2(H2O)4 (II) have been prepared by concentrating of acetonitrile and aqueous solutions respectively. According to X-ray data, the complex I consists of binuclear molecules with Cu–O 1.969 A, Cu–N 2.114 A. The Cu…Cu distance was found to be 2.766 A, one of the longest for dimeric structures, apparently, due to the high acidity of trifluoroacetic acid. The coordination environment of Cu atom in II can be described as 4 + 2: 2 Cu–O (H2O) 1.937 A, 2 Cu–O (CF3COO) 1.985 A, 2 Cu–O (H2O) 2.447 A. The mononuclear structure is stabilized by formation of two intra- and six intermolecular hydrogen bonds. Synthese und Kristallstruktur der Kupfer(II)-trifluoroacetat Cu2(CF3COO)4 · 2 CH3CN und Cu(CF3COO)2(H2O)4 Cu2(CF3COO)4 · 2 CH3CN (I) und Cu(CF3COO)2(H2O)4 (II) wurden durch Konzentrieren von Losungen in Acetonitril (I) bzw. Wasser (–10 °C) (II) erhalten. Die Struktur von I besteht aus zweikernigen Komplexen mit Cu–O 1.969 A, Cu–N 2.114 A. Der Cu…Cu-Abstand ist mit 2.766 A fur dimere Strukturen einer der langsten bisher gefundenen, offenbar als Folge der hohen Aciditat der Trifluoressigsaure. Die koordinative Umgebung von Cu in II kann mit 4 + 2 beschrieben werden: 2 Cu–O (H2O) 1.937 A, 2 Cu–O (CF3COO) 1.985 A, 2 Cu–O (H2O) 2.447 A. Die einkernige Struktur wird durch zwei intra- und sechs intermolekulare Wasserstoffbrucken stabilisiert.

Stabilization of silicon nanoparticles by carbenes

Sodium reduction of a mixture of tetrabromosilane with imidazole ionic liquids in organic solvents gives dispersions of silicon nanoparticles stabilized by carbene ligands. It was shown that the size of silicon nanoclusters depends on the size of substituents at nitrogen atoms of 1,3-dialkylimidazol-2-ylidenes.

Synthesis and structure of acetonitrile solvates of copper(II) monofluoroacetate and silver(I) trifluoroacetate, [Cu2(CH2FCOO)4·2CH 3CN](CH3CN) and Ag3(CF3COO)3(CH3CN)2

AbstractCompounds [Cu2(CH2FCOO)4· 2CH3CN](CH3CN) (I) and Ag3(CF3COO)3(CH3CN)2(II) were synthesized and studied by X-ray structural analysis. Crystals Iare monoclinic, space group C2/c, a= 27.854(6), b= 8.286(2), c= 19.428(4) Å, β = 106.82(3)°, V= 4292(2) Å3, Z= 8, R1= 0.0426; crystals IIare triclinic, space group

Bis(dimethylammonium) terephthalate

P\overline 1

Preparation of mesoporous aluminum hydroxide and oxide in ionic liquids

, a= 8.676(2), b= 9.819(2), c= 11.961(2) Å, α = 95.27(3), β = 109.59(3)°, γ = 104.60(3)°, V= 911.4(3) Å3, Z= 2, R1= 0.0252. Structure Iis composed of the structural units (“lanterns”) typical of copper(II) carboxylates. The presence of an additional acetonitrile molecule noncoordinated by the copper atoms makes it possible to consider compound Ias a lattice clathrate. Structure IIhas no analogs among the silver carboxylates. It simultaneously contains silver atoms with coordination numbers varying from 2 to 4.

Superprotonic high temperature phase and refinement of the low temperature structure of CsHSeO4

Thulium trifluoroacetate compounds have been synthesized, Tm(CF3COO)3 · 3H2O (I) and Tm2(CF3COO)6 · 2CF3COOH · 3H2O (II). The structure of I has been refined by the Rietveld method on the basis of the structural data for Cd(CF3COO)3 · 3H2O. The structure of II has been solved in a single-crystal X-ray diffraction study. Compound I has been studied by thermal analysis. Crystals of I and II are monoclinic: for Ia = 9.062(2) Å, b = 18.678(3) Å, c = 9.687(2) Å, β = 113.93(1)°, Z = 2, space group P21/c, R1 = 0.062; for IIa = 8.560(4) Å, b = 19.866(5) Å, c = 20.813(7) Å, β = 101.69(4)°, Z = 8, space group C2/c, R1 = 0.0392. In the molecular structure of I, thulium atoms are bonded in pairs through four bridging trifluoroacetate anions to form dimers. The coordination polyhedron of the thulium atom also includes the three O atoms of the water molecules and the O atom of the monodentate trifluoroacetate group; the coordination number of the thulium atom is eight. In the chain structure of II, there are two crystallographically independent thulium atoms with coordination numbers 8 and 9. The coordination polyhedra of the Tm(1) and Tm(2) atoms are a distorted monocapped tetragonal antiprism and a distorted tetragonal antiprism, respectively. The Tm-O bond lengths are in the range 2.28(1)–2.85(2) Å. The thulium atoms are bound into chains through carboxylate groups. These chains are linked into layers through hydrogen bonds.

Tris(ethane-1,2-diamine)copper(II) bis-(trifluoro-acetate).

The asymmetric unit of the title compound, 2C2H8N+·C8H4O42−, comprises two crystallographically independent dimethylammonium cations and two half-terephthalate anions. The latter are each disposed about an inversion centre. N—H⋯O hydrogen bonds link the ions into a three-dimensional framework.

Crystal structures of [N(CH3)4](HSeO4) at 298, 363, and 380 K

The neutron diffraction study of Na3H5(SeO4)4 single crystals at 298 and 85 K has confirmed the positions of nonhydrogen atoms obtained in the X-ray diffraction study. Contrary to the X-ray diffraction data, the neutron diffraction data indicate that all the three independent protons are ordered and participate in two asymmetric and one symmetric hydrogen bonds, with the O⋯O distances being 2.68, 2.61, and 2.48 Å. The system of hydrogen bonds is built by complicated chains.