Volume 63, Issue 10

The discovery of high-temperature superconductivity in the fluoride-doped arsenide oxides REFeAs(O 1−x F x ) (RE = early rare earth element) with transition temperatures as high as 55 K has led to a true renaissance in superconductivity research. These arsenide oxides constitute a rather small fraction of a much larger family of compounds with the tetragonal ZrCuSiAs-type structure (space group P4/nmm), among them pnictide oxides and fluorides, chalcogenide oxides and fluorides as well as silicide and germanide hydrides. Besides the spectacular superconductivity, these materials have further interesting properties with respect to magnetic ordering, transparent semiconducting behavior or optical properties. The crystal chemical and chemical bonding peculiarities as well as the broadly varying physical properties are reviewed herein.

The reaction of diethylaluminum hydride with the hydrazine derivatives 1-aminopyrrole and 1- aminopiperidine afforded the corresponding dialkylaluminum hydrazides (1 and 2) by the release of elemental hydrogen. Both products are dimeric in the solid state. While 1 adopts a cis arrangement of the pyrrole groups, a trans configuration was determined for the piperidine compound 2. Only 1 gives an equilibrium mixture of cis and trans isomers in solution. Similar compounds (3 and 4) were obtained by the treatment of the same hydrazines with di(tert-butyl)gallium hydride. Both products exhibit the trans configuration in the solid state, but interestingly only the piperidine derivative 4 shows a cis/trans equilibrium in solution.

The reaction of the diimine ligand 1,2-bis(1,3-diisopropyl-4,5-dimethylimidazolin-2-imino)ethane (BL iPr ) with tetrameric [Cp*RuCl] 4 in a 1 : 0.75 ratio afforded the complex salt [1][2] containing the 16-electron half-sandwich cation [Cp*Ru(BL iPr )]+ (1) and the dinuclear anion [Cp*Ru(μ- Cl) 3 RuCp*] − (2). The X-ray crystal structures of [1][2]·31/2THF (monoclinic, space group P2 1 /n, Z = 4) and of [1][2]·THF (monoclinic, space group C2/m, Z = 4) are reported, allowing the structural characterization of the unprecedented anion 2, in which two [(η 5 -C 5 Me 5 )Ru(II)] moieties are bridged by three μ 2 -chlorine atoms.

The photocatalytic activity of InTaO 4 has been studied regarding the effect of a substitution of In by Ni, of the performance of NiO as well as Ag 2 O as co-catalysts, and especially of the products of different methods of preparation (solid state reaction and/or sol-gel process) and their particle sizes. Solid state reactions and sol-gel procedures were used to synthesise different products for the catalytic reaction in a reactor vessel equipped with amercury UV lamp. The optical properties and the band gap values of the different products were evaluated by reflectance spectroscopy, and the microstructure parameters of the crystalline products were determined by an elaborate profile analysis of the X-ray diagrams. The evolution of H 2 and O 2 under irradiation was quantified by a GC setup. The causes for the deviations of the performance of these catalysts from the values reported elsewhere are discussed.

Treatment of the copper(I) trifluoromethanesulphonate toluene complex {[Cu(CF 3 SO 3 )] 2 · C 6 H 5 Me} (1) with phthalazine (phtz, C 8 H 6 N 2 ) in dichloromethane-acetonitrile solution yielded, via the bis(acetonitrile)tris(μ-phthalazine)dicopper(I) trifluoromethanesulphonate intermediate (2), the novel bis(phthalazine)tris(μ-phthalazine)dicopper(I) trifluoromethanesulphonate salt (3). Compound 3 was completely characterised and the molecular structure determined by single-crystal X-ray diffraction. Complex 3 crystallises in the monoclinic system, space group C2/c, with a = 26.9527(10), b = 10.9558(7), c = 19.2104(10) Å , β = 127.268(2)◦, V = 4514.3(4) Å 3 and Z = 4. The copper(I) coordination geometry is tetrahedral, each copper centre being linked to four phthalazine molecules. Dicationic units of 3 which present an unusual paddle wheel-like shape constitute appropriate organometallic building blocks for the construction of a supramolecular solid-state architecture. The analysis of the packing of the molecules of 3 in the crystal revealed an unprecedented 2-dimensional network, resulting from intermolecular π-π and electrostatic interactions.

Two new paratungstate-based compounds were isolated from the acetate buffer solution containing decatungstate [W 10 O 32 ] 4− at different reaction temperatures. The two compounds have been characterized by elemental analysis, IR spectroscopy, thermogravimetric analysis (TGA), and single crystal X-ray diffraction, and formulated as (H 3 O) 3 [{K(H 2 O)} 2 {Na 2 (H 2 O) 8 } 2 (Na 0.5 H 2 O) 2 (H 2 W 12 O 2 )] ・ 6H 2 O (1) and (H 3 O) 2 [{K(H 2 O) 4 } 2 {Na 3 (H 2 O) 9 } 2 (H 2 W 12 O 42 )]·2H 2 O (2). Compounds 1 and 2 exhibit different three-dimensional architectures with bridging sodium and potassium as countercations for the paratungstate anion. Compound 1 displays an intense blue luminescence in the solid state. The structural transformation from [W 10 O 32 ] 4− to [H 2 W 12 O 42 ] 10− in an acetate buffer provides a route for the synthesis of new paratungstate-based compounds.

4-Aminopyridinium tetrabromocadmate(II) monohydrate (1) crystallizes in the orthorhombic space group Pbcm with a = 6.876(2), b = 14.089(2), and c = 18.845(2) Å , Z = 4, T = 296 K. In the crystal structure, a [CdBr 4 ] 2− anion, a 4-aminopyridinium cation, and a water molecule are alternately connected into chains by hydrogen bonds N-H···Br and O-H···Br. 2,3,5,6- Tetramethylpyrazinium tetrabromocadmate(II) (2) crystallizes in the orthorhombic space group P2 1 2 1 2 1 with a = 14.640(12), b = 15.615(7), c = 6.686(5) Å , Z = 4, T = 296 K. In the crystal structure, a [CdBr 4 ] 2− anion and a 2,3,5,6-tetramethylpyrazinium cation are interconnected by bifurcated hydrogen bonds N-H· · ·2Br and form infinite chains. 81 Br NQR spectra with three lines with an intensity ratio of 1 : 1 : 2 (77 K ≤ T ≤ ca. 325 K) and four lines with an intensity ratio of 1 : 1 : 1 : 1 (77 K ≤ T ≤ ca. 330 K) were observed for crystalline 1 and 2, respectively, which are consistent with the crystal structure data. DSC measurements showed the existence of thermal anomalies at high temperatures in both 1 and 2.

Configurationally highly pure (E,E)-4,4´-bis(styryl)biphenyls 2a - e were obtained by Siegrist reactions of 4,4´-dimethylbiphenyl 3 and alkoxy-substituted benzaldimines (4a - e). DSC measurements have indicated different crystalline modifications of these conjugated compounds. The stilbenoid chromophores of 2a - e are compared to the stilbenoid chromophores in the OPV series, which have a similar length of conjugation. The intense fluorescence and the high transparency in the visible region are promising properties for an application of the donor-substituted compounds 2a - e in twophoton absorption (TPA) techniques.

Dimethylphosphinylmethylamine (1) and its aldimines 2 were used for the preparation of dimethyl and diethyl α-amino(aryl)methylphosphonates 3a - l via imine hydrophosphonylation and Kabachnik-Fields reaction. Their acid hydrolysis gave rise to the corresponding α-aminophosphonic acids 4a - e. Compounds 3 and 4 have two different phosphorus-containing groups - phosphonyl and dimethylphosphinyl - and might have interesting biological activity.

2-(N,N-Dimethylaminomethyl)thiophenol, (1, HL), is present as a non-zwitterionic aminothiol in the solid state, exhibiting an intramolecular S-H···N hydrogen bond. The S···N distances of the two independent molecules in the asymmetric unit are 2.929(10) and 3.050(10) Å. This structural feature is also present in an ab initio (MP2/6-31G*) optimized molecular structure. The investigation of the hydrogen bond by ab initio methods supports an n(N)-σ *(S-H) interaction as the reason for this bond type. On the basis of data from potentiometric acid-base titrations of a 0.01 M aqueous solution of [H 2 L]Cl with a 0.1 M aqueous solution of sodium hydroxide, values of 4.09±0.01 and 11.50±0.01 were obtained for pK a1 and pK a2 of [H 2 L] + . pK a1 is much smaller than pK a of thiophenol while pK a2 is bigger than pK a of benzyldimethylamine. The increased difference between pK a1 and pK a2 is attributed to the stabilization of HL by the intramolecular S-H···N hydrogen bond.

Six new cyclophane molecules (5 - 10) were synthesized from α,α´-bis(N-tosyl-4-aminophenyl)- 1,4-diisopropylbenzene and α,α´-bis[4-(n-bromoalkyloxy)phenyl]-1,4-diisopropylbenzene. The crystal and molecular structures of α,α´-bis(4-aminophenyl)-1,4-diisopropylbenzene (3), α,α´-bis (N-tosyl-4-aminophenyl)-1,4-diisopropylbenzene 4 and the ditosyl derivative of the diazadioxacyclophane 6 were determined. The noncyclic compounds 3 and 4 display the anti conformation. Diazadioxacyclophane 6 possesses a central cavity that might be exploited to accommodate guest molecules, but some conformational change would probably be required.

4-Benzylidene-2-phenyl-5(4H)-oxazolones react with Wittig-Horner reagents in the presence of alcoholic sodium alkoxide to give novel dioxopyrrolidinephosphonates, diethyl [3-(benzoylamino)- 1-cyano-2-oxo-4-phenylbut-3-en-1-yl]phosphonate and phosphonoalkenoate derivatives. Both the phosphonate adducts and the ester products were also isolated from the reaction of oxazolones with triethyl phosphonoacetate using alcoholic sodium ethoxide and/or sodium hydride as a base. Possible reaction mechanisms are considered, and the structural assignments are based on analytical and spectroscopic results. The biological evaluation of the new compounds is reported.

Phytochemical investigation of the chloroform soluble fraction of the methanolic extract of Cotoneaster racemiflora resulted in the isolation of two new aromatic esters named cotonoates A (1) and B (2) along with the known compound methyl 3,4-dihydroxy-5-methoxybenzoate (3). The structures of the new compounds have been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. Compound 3 shows significant antioxidant and lipoxygenase inhibitory activities.

Val-Geninthiocin (2), a new member of thiopeptide antibiotics, was isolated from the mycelium of Streptomyces sp. RSF18, along with the closely related geninthiocin (1) and the macrolide, chalcomycin. By intensive NMR and MS studies, Val-geninthiocin (2) was identified as desoxygeninthiocin, a thiopeptide, containing several oxazole and thiazole units and a number of unusual amino acids. Compound 2 shows potent activity against Gram-positive bacteria and minor antifungal activity, while it is not effective against Gram-negative bacteria or microalgae. Here we describe the fermentation, isolation and structure elucidation as well as the biological activity of 2.

First principles calculations of the electronic band structures of zinc blende-type GaN and BN and their 1 : 1 mixture B 0.5 Ga 0.5 N were carried out within DFT using the augmented plane wave method with both GGA and LDA approximations for the effects of exchange and correlation. Equilibrium lattice constants were determined from the total-energy minimization method. The results are compared with those of previous calculations and with experimental measurements. In agreement with these data, ZB-BN is an indirect (Γ → X) wide-gap semiconductor (4.35 eV) while ZB-GaN has a direct gap of 1.9 eV at Γ . For ZB B 0.5 Ga 0.5 N we predict a direct band gap of 3.35 eV. Electron charge densities are computed for the unit cell, and ionicity factors are derived for all systems.

The heterocyclic selenium(IV) oxide L SeO is reduced by [Pd(COD)Cl 2 ] in MeCN solution to produce trans- [Pd(L Se ) 2 Cl 2 ] (2) (L Se = 2,3-dihydro-2-isopropyl-7-(Nisopropylcarbamoyl)- 1,2-benzisoselenazole-3-oxide). Complex 2 crystallizes in the triclinic space group P1̅ with a = 10.700(1), b = 10.871(1), c = 15.656(2) Å , α = 104.51(1), β = 94.59(1), γ = 95.25(1) ◦ , V = 1745.5(3) Å 3 , and Z = 2. The COD is oxidized to 5,6-epoxycyclooctene.

A new cyathane-xyloside derivative, named erinacine R, was isolated from the mycelia of basidiomycete Hericium erinaceum. The structure of this compound was elucidated by spectral methods including 2D NMR experiments.