X-ray crystal structures of Al-doped (Y,Ca)Ba2Cu3O(7-y) whiskers.

Al(+3)-doped (Y,Ca)Ba2Cu3O(7-y) (YBCO) whiskers have been synthesized using a solid-state reaction technique. These materials are promising candidates for solid-state THz applications based on sequences of Josephson Junctions (IJJs). Alumina addition was systematically varied and the effect of aluminium incorporation on the structure has been investigated using single-crystal X-ray diffraction. Aluminium only replaces Cu atoms in the O-Cu-O-Cu chains and a gradual transition from orthorhombic to tetragonal space group occurs, thus increasing the Al content. A gradual modification of the coordination sphere of the copper site has also been observed. The Ca(2+) ion substitutes mainly the Y(3+) ion and also, to a small extent, the Ba(2+) ion.

Preparation and characterization of aryl or heteroaryl(3-indolyl)methylium o-benzenedisulfonimides.

An initial study has been accomplished into the synthetic feasibility of the preparation of diarylcarbenium salt via the direct coupling of aryl (or heteroaryl) aldehydes and arenes (or heteroaryl analogues) in the presence of a strong organic Brønsted acid. A number of stabilized aryl or heteroaryl(3-indolyl)carbenium ions, never previously prepared in the solid state, have been isolated in excellent yields as highly stable o-benzenedisulfonimide salts and have been fully characterized. Their purity has been proven by spectroscopic methods and chemical reduction with NaBH(4). An X-ray crystal structure analysis has been performed on one of the products: an azafulvenium species was shown to be the exclusive structure in the solid state.

Superbase promoted synthesis of dienamides as useful intermediates for the synthesis of α-ketoamides, γ-lactams and cyclic imino ethers.

Alkoxydienamides 2 have been synthesized exploiting the reactivity of α,ß-unsaturated acetals 1 with isocyanates in the presence of Schlosser's superbase LIC-KOR. In a mild acidic medium, 2 can then be promptly converted both into α-ketoamides 3 and into substituted 2-pyrrolidinones 4 or imino ethers 5 by choosing the appropriate experimental conditions.

Detection of weak intramolecular interactions in Ru(3)(CO)(12) by topological analysis of charge density distributions.

The presence of weak intramolecular interactions among the axial carbon atoms in Ru(3)(CO)(12), previously detected by topological analysis of the 120 K X-ray derived charge density, has been here confirmed by theoretical calculations on the isolated, "gas-phase" molecule, using the all-electron B97D/3-21G approach, as well as by further experimental determinations of higher accuracy on data collected at 100 K. The importance of using density functional theory (DFT) approaches where dispersion terms are explicitly added to the usual Kohn-Sham energy to reproduce such weak intramolecular interactions has been evidenced. This result confirms the multipole approach as an efficient and sensitive tool to extract fine details of electron density distributions.

4-({4-[Bis(2-cyano-eth-yl)amino]-phen-yl}diazen-yl)benzene-sulfonamide.

In the title compound, C(18)H(16)N(6)O(2)S, which belongs to the family of azo dyes, the dihedral angle between the benzene rings is 26.16 (7)°. In the crystal, mol-ecules are joined by N-H⋯N and C-H⋯N hydrogen bonds into double chains parallel to the a axis.

o-Benzoquinone dioxime.

The title compound, C(6)H(6)N(2)O(2), was obtained as a product of an in vitro study of the metabolism of benzofuroxan. The molecule exhibits a amphi configuration of the oxime groups C=N-OH. One oxime group is involved in the formation of a strong intra-molecular O-H⋯N hydrogen bond, while another links mol-ecules into zigzag chains along the c axis via inter-molecular O-H⋯N hydrogen bonds.

3-Phenyl-sulfanyl-4-phenyl-sulfonyl-1,2,5-oxadiazole 2-oxide.

In the title compound, C(14)H(10)N(2)O(4)S(2),the furoxan heterocyclic ring and the two S atoms are almost co-planar, with a mean deviation of 0.036 Å. The bond lengths in the penta-gonal ring show electron delocalization and the furoxan N-O bond length is quite short [1.211 (3) Å]. The dihedral angles between the central ring and pendant phenyl rings are 78.05 (14) and 84.28 (2)°.

2,3,4,6-Tetra-O-acetyl-2-phthalimido-ß-d-glucopyran-oside.

In the crystal structure of the title compound, C(24)H(27)NO(11), a substituted tetra-acetyl glucopyran-oside derivative, weak inter-molecular C-H⋯O hydrogen bonds link the mol-ecules into ribbons propagated in [010]. The d configuration has been attributed on the basis of the synthesis and the ß anomer has been determined from the structure.

Mercuric cyanide as a receptor of pyrene.

Cocrystallization of pyrene with Hg(CN)(2) gives a new clathrate, namely bis[dicyanidomercury(II)] pyrene solvate, [Hg(CN)(2)](2) x C(16)H(10), with molecules of pyrene embedded in cavities of the slightly deformed structure of the mercuric salt; the weak intermolecular N...Hg interactions present in pure Hg(CN)(2) are maintained in the cocrystal. The X-ray analysis of the resulting compound reveals unusual organic-inorganic interactions. One molecule of Hg(CN)(2) lies on a crystallographic mirror plane, while in the other, only the Hg atom is on the mirror plane. The molecule of pyrene is cut by a mirror plane perpendicular to the plane of the molecule.

Metallohosts Derived from the Assembly of Sugars around Transition Metals: The Complexation of Alkali Metal Cations.

The diacetone glucose (DAGH, 1,2:5,6-di-O-isopropylidene-alpha-D-glucofuranose) monoanion DAG binds as a terminal alkoxo ligand to a variety of transition metals. When it is used in excess, with respect to the oxidation state of the metal, homoleptic anionic complexes [M'(DAG)(6)](3)(-) are formed. Such complexes contain oxygen-rich cavities between pairs of DAG ligands appropriate for binding alkali metal cations. The anionic complexes have been obtained by using [Li(DAG)], 1, and [Na(DAG)], 2, whose syntheses and characterization are reported here. The reaction of 1 and 2 with [V(DAG)(3)] gave [V(DAG)(6)Li(3)], 3, and [V(DAG)(6)Na(3)], 4, respectively. An alternative synthesis of 3 and 4 involves the metathesis reaction of 1 and 2 with [VCl(3)(thf)(3)]. This strategy also led to the synthesis of [Cr(DAG)(6)Li(3)], 5, and [Ti(DAG)(6)Li(3)], 6. Three pairs of DAG shape a cavity appropriate for three lithium cations in the case of complexes 3, 5, and 6; a cavity is formed for three sodium cations in the case of 4, where the alkali cation is in a tetrahedral O(4) environment. In the anionic manganese derivative [Mn(Cl)(DAG)(4)](3)(-), the four DAG units arrange in such a way as to bind four Li cations, which form a cationic cage [Mn(Cl)(DAG)(4)Li(4)](+), and Cl(-) is bound inside as [Mn(Cl)(DAG)(4)Li(4)(&mgr;(4)-Cl)], 7. Crystallographic details: 4, prism, P2(1), a = 14.735(10) Å, b = 15.033(9) Å, c= 21.021(10) Å, beta = 107.34(2) degrees, V= 4445(5) Å(3), Z = 2, and R = 7.60; 5, prismatic, C2, a = 22.671(9) Å, b = 18.785(5) Å, c = 13.886(4) Å, beta = 126.39(2) degrees, V= 4761(3) Å(3), Z = 2, and R = 7.32; 6, prismatic, P2(1), a= 13.888(5) Å, b = 18.750(5) Å, c= 17.933(5) Å, beta = 91.84(2) degrees, V = 4667(2) Å(3), Z = 2, and R = 8.75; 7, prismatic, P2(1), a = 13.306(7) Å, b= 21.311(11) Å, c = 13.376(6) Å, beta = 95.01(2) degrees, V = 3779(3) Å(3), Z = 2, and R = 9.33.