Volume 72, Issue 7

Poly(cyclic) oxamates represent novel and potentially multidentate ligands for coordination chemistry. To obtain them, the treatment of 2-nitroaniline with two equivalents of oxalyl chloride afforded N,N ′-bis(2-nitrophenyl)oxalamide ( 1 ), and by reduction of 1 with [NH 4 ][CO 2 H] and Pd/C, N,N ′-bis(2-aminophenyl)oxalamide ( 2 , bapoxH 6 ) was synthesized. After the addition of an equimolar amount of oxalyl chloride to a THF solution of 2 and aqueous work-up the 24-membered macrocycle H 8 L 2 was obtained. In analogues experiments, the addition of ethoxalyl and oxalyl chloride to 2 afforded the 36-membered macrocycle H 12 L 3 . The addition of Cu(OAc) 2 ·H 2 O and NaOH to 2 gave rise to the formation of [Cu 2 (bapoxH 4 )(OAc) 2 ] ( 4 ). The identities of 1 , 2 and H 8 L 2 were determined by elemental analysis, IR, NMR spectroscopic studies and by mass spectrometry. The solid state structures of H 8 L 2 , H 12 L 3 and 4 have been determined by single-crystal X-ray diffraction studies. Macrocycle H 12 L 3 forms chains through intermolecular hydrogen bonds, while packing of 4 consists of layers held by intermolecular dispersion and hydrogen bond interactions. 24-mer H 8 L 2 forms a cavity with a diameter of about 7.5 Å corresponding to an accessible volume of about 120 Å 3 according to the well-established 55% solution and was found to bind bromide and iodide anions selectively.

Treatment of [Mo 2 S 2 O 2 (H 2 O) 6 ] 2+ with racemic tartaric acid (tartH 4 ) in the presence of sodium hydroxide and cesium chloride in aqueous solution led to the isolation of a new tetra-molybdenum ring cluster Cs 4 [Mo 2 O 2 (μ-S) 2 ] 2 (μ 4 -tart) 2 . The cyclic cluster polyanion consists of two dinuclear [Mo 2 O 2 (μ-S) 2 ] 2+ moieties and two bridging tart 4− ligands. The cyclic polyoxothiomolybdate cluster, supported on the mesoporous silica SBA-15, was tested for heterogenerous catalysis in thiophene hydrodesulfurization.

Two new pyrrolo[2,3- d ]pyrimidines (7-deazapurines) were synthesized in high yields by the reaction of 2-amino-1-methyl-4,5-diphenyl-1 H -pyrrole-3-carbonitrile with triethyl orthoformate followed by cyclocondensation with methyl or benzyl amine in refluxing glacial acetic acid or using ultrasonic irradiation containing a catalytic amount of glacial acetic acid at 60°C. For each product, the correct structural isomer was identified using the FT-IR, 1 H NMR, 13 C NMR, 2D nuclear Overhauser effect spectroscopy spectral and microanalytical data together with comparison of the experimental and calculated chemical shifts at the B3LYP/6-31+G(d,p) level of theory. Furthermore, the synthesized compounds were evaluated for their antibacterial activity against Gram-positive bacteria ( Staphylococcus aureus and Micrococcus luteus ) and Gram-negative bacteria ( Escherichia coli ) by the agar dilution method using 24-well microtiter plates.

Coupling of diethynyldiphenylsilane ( 1 ) with aryl halides under Sonogashira conditions affords the symmetrical diarylacetylenes bis(2-methylpyridin-5-yl)acetylene ( 2 ), bis(4-fluorophenyl)acetylene ( 3 ) and bis(4-trifluoromethylphenyl)acetylene ( 4 ) in 60% to 82% yield. In the case of 2 , the by-product bis(2-methylpyridin-5-yl)butadiyne ( 2a ) was isolated in 12% yield. The occurring desilylation reaction was investigated by treating bis(phenylethynyl)diphenylsilane ( 5 ) under the same conditions. The formation of 1-fluoro-4-(phenylethynyl)benzene ( 6 ), 1-trifluoromethyl-4-(phenylethynyl)benzene ( 7 ) and (tetrafluoropyridin- 4-yl)ethynylbenzene ( 8 ) in 70 to 84% yield and the cleavage of hexaphenylcyclotrisiloxane were observed in all cases.

CoFe 2 O 4 @SiO 2 -PrNH 2 nanoparticles have been used as an efficient catalyst for the preparation of benzodiazepines by multi-component reactions of 1,2-phenylenediamine, dimedone, different aldehydes or Meldrum’s acid and isocyanides. This method provides several advantages including mild reaction conditions, the applicability to a wide range of substrates, the reusability of the catalyst and low catalyst loading.

The new compound Co 9 (OH) 14 [SO 4 ] 2 was synthesized using a hydrothermal method from LiF, Na 2 SO 3 , and Co(CH 3 COO) 2 ·4H 2 O in a molar ratio of 1:1:1 in the presence of atmospheric oxygen. Its crystal structure was determined from single crystal X-ray diffraction data. Co 9 (OH) 14 [SO 4 ] 2 crystallizes in the triclinic system, space group P 1̅ with a =7.693(2) Å, b =8.318(2) Å, c =8.351(2) Å, α =82.375(5)°, β =77.832(4)°, γ =68.395(4)°, V =484.8(2) Å 3 , and Z =2. Its structure is composed of cobalt-containing sheets interconnected by SO 4 tetrahedra. Bent and symmetrically trifurcated hydrogen bonds have been observed. Furthermore, structural similarities with hydrozincite and brucite minerals have been noticed.

GdCuMg has been synthesized by induction-melting of the elements in a sealed niobium ampoule followed by annealing in a muffle furnace. The sample was studied by powder and single crystal X-ray diffraction: ZrNiAl type, P 6̅2 m ( a =749.2(4), c =403.3(1) pm), wR 2=0.0242, 315 F 2 values and 15 variables. Temperature dependent magnetic susceptibility measurements have revealed an experimental magnetic moment of 8.54(1) μ B per Gd atom. GdCuMg orders ferromagnetically below T C =82.2(5) K and based on the magnetization isotherms it can be classified as a soft ferromagnet.

The crystal structure of NH 4 [C(CN) 3 ] has been determined via X-ray single-crystal methods at 203(2) K corroborating earlier results. Additionally, the hydrogen positions have been determined and the Raman spectrum of the title compound recorded on single crystals. The spectroscopic results are compared to those for related compounds.

Treatment of [Ru(acac) 3 ] (acac − =acetylacetonate) with (2,4,5-Me 3 C 6 H 2 )MgBr, followed by column chromatography in air, afforded the homoleptic tetraaryl-ruthenium(IV) complex [Ru(2,4,5-Me 3 C 6 H 2 ) 4 ] ( 1 ) in moderate yield. The product was characterized by proton NMR spectroscopy and microanalyses. Its crystal structure has also been established by X-ray crystallography.