Volume 71, Issue 7

Intermetallic compounds with the equiatomic composition Ce TX that crystallize with the orthorhombic TiNiSi-type structure can be synthesized with electron-rich transition metals ( T ) and X = Zn, Al, Ga, Si, Ge, Sn, As, Sb, and Bi. The present review focusses on the crystal chemistry and chemical bonding of these Ce TX phases and on their physical properties, 119 Sn and 121 Sb Mössbauer spectra, high-pressure effects, hydrogenation reactions and the formation of solid solutions in order to elucidate structure–property relationships. This paper is the final one of a series of four reviews on equiatomic intermetallic cerium compounds [Part I: Z. Naturforsch . 2015 , 70b , 289; Part II: Z. Naturforsch . 2015 , 70b , 695; Part III: Z. Naturforsch . 2016 , 71b , 165].

The reactions of 5-azido-3-methyl-1-phenyl-1 H -pyrazole-4-carbaldehyde (azidopyrazole) with several classes of organophosphorus reagents: phosphonium ylides, Wittig-Horner reagents, dialkylphosphonates, trialkylphosphites, tris(dialkylamino)phosphanes, triphenylstibane, triphenylarsane, and Lawesson’s reagent are reported. Structural reasoning for the new products was based on compatible analytical and spectral data. The cytotoxic activity of most of the new products was evaluated against human breast carcinoma cell line (MCF7) and human hepatocellular carcinoma cell line(HepG2). Certain tested compounds showed promising results.

A concise and CuI nanoparticle-catalyzed synthesis of tetrahydrochromenediones and dihydropyrano[ c ]chromenediones under solvent-free grinding conditions via the three-component condensation reaction of Meldrum’s acid, an aromatic aldehyde, and an active methylene compound, including dimedone or 4-hydroxycoumarin, was developed. This new method gives desirable advantages such as simple reaction setup, very mild reaction conditions, production of the desired products in high yields without by-products, recyclability of the catalyst, and environmentally benign procedure.

The new supramolecular compound [Fe 2 (AsMo 7 O 27 ) 2 ](H 2 en) 2 (NH 4 ) 8 ·6H 2 O ( 1 ) (en = ethylenediamine) has been synthesized in aqueous solution and characterized by elemental analysis, thermal analysis, and single crystal X-ray diffraction. The structural analysis has revealed that 1 represents the first example of a polyoxometalate-based sandwich-type supramolecular hybrid constructed from hexalacunary building blocks. Owing to the presence of ethylenediammonium cations, the [Fe 2 (AsMo 7 O 27 ) 2 ] 12– units are stabilized by multiple circular hydrogen bonds extending the structure into a 2D supramolecular framework. The magnetic properties and antitumor activities of 1 have also been studied.

The treatment of 3- O -acetyl-1,2- O -isopropylidene-4,5-di- O -methanesulfonyl- β - d -fructopyranose with sodium methoxide led to the crystalline epoxy-sugar 3,4-anhydro-1,2- O -isopropylidene-5- O -methanesulfonyl- β - d -tagatopyranose, the structure of which was determined by X-ray diffraction. Solvolysis of the epoxide with methanolic hydrogen chloride and subsequent mesylation gave methyl 4-chloro-4-deoxy-1,3,5-tri- O -methanesulfonyl- β - d -fructopyranoside which was also characterized by X-ray structure determination.

Three chromium(III) 1,2,4-diazaphospholide complexes were prepared: 3,5-di- tert -butyl-1,2,4-diazaphospholide chromium(III) dichloride [( η 2 -3,5- t Bu 2 dp)Cr(THF) 2 Cl 2 ] ( 1 ), 3,5-di-phenyl-1,2,4-diazaphospholide chromium(III) dichloride [( η 2 -3,5-Ph 2 dp)Cr(THF) 2 Cl 2 ] ( 2 ), and 2,6-bis( N -1,2,4-diazaphosphol-1-yl)pyridine chromium(III) trichloride {[2,6-bis( N -1,2,4-diazaphosphol-1-yl)pyridine]CrCl 3 } ( 3 ). X-ray diffraction analysis has shown that these six-coordinate complexes each have a pseudo-octahedral configuration. Electron paramagnetic resonance (EPR) spectroscopy data for complex 1 for the paramagnetic S = 3/2 system ( d 3 electron configuration) confirm a Cr(III) center in the octahedral coordination environment. The magnetic susceptibility of complex 1 followed the Curie–Weiss law well between 25 and 300 K. The magnetic moment of 1 was found to be close to the spin-only magnetic moment expected for three unpaired electrons (3.87 μ B ).

A series of tetracarboxamide and macrocyclic tripeptides have been prepared starting from 3,5 - bis[ N -(1-hydrazinyl-1-oxo-3-phenylpropan-2-yl)]pyridinecarboxamide 4 as starting material, which was synthesized from dinicotinic acid 1 . Treatment of 4 with 1,4-diaminobutane, 1,6-diaminohexane, or cycloalkanone derivatives gave the corresponding macrocyclic tetracarboxamides ( 5a , b ) and cycloalkyl hydrazone derivatives ( 6a–c ), respectively. Additionally, the reaction of 4 with acetophenone or acetylpyridine derivatives gave the corresponding Schiff base derivatives 7a–e and 8a–c , respectively. Also, carboxylic acid hydrazide 4 was treated with acid anhydrides in glacial acetic acid to afford the corresponding diimide tetracarboxamide derivatives 9a , b , 10, and 11 , respectively. The structures of newly synthesized compounds are established by physical and spectral data evidences. Some of the synthesized compounds were screened as antimicrobial agents.

Potential high energetic dense oxidizers with the 1,1,1-trinitropropan-2-yl moiety are described in this study. The urea, N , N ′-bis(1,1,1-trinitropropan-2-yl)urea ( 1 ), is synthesized by the reaction of urea with acetaldehyde and trinitromethane. The reaction of 1,1,1-trinitropropan-2-ol ( 2 ) with the reagent chlorosulfonyl isocyanate results in the formation of 1,1,1-trinitroprop-2-yl carbamate ( 3 ). The nitration of 3 with anhydrous nitric and sulfuric acid yields the nitrocarbamate ( 4 ). All compounds were fully characterized by multinuclear NMR ( 1 H, 13 C, 14/15 N) and vibrational spectroscopy, mass spectrometry and elemental analysis (C,H,N). For analysis of the thermostability differential scanning calorimetry (DSC) was used. Energetic properties, the sensitivities towards impact, friction and electrostatic discharge were tested and compared with the corresponding 2,2,2-trinitroethyl and 3,3,3-trinitropropyl derivatives. The crystal structures of two compounds with that of the 1,1,1-trinitroprop-2-yl moiety have been determined by low temperature X-ray diffraction and discussed. The energies of formation were evaluated and several detonation parameters such as the velocity of detonation and the propulsion performance were calculated with the program package explo5 .

A general difficulty in the comparison of catalysts regarding their electrochemical activities is the significant dependency on the electrode preparation method. In addition to single-crystal, thin-film, and polycrystalline electrodes, most electrocatalysts contain a physical mixture of catalytically active nanocrystals (NCs), conductive carbon support, and binding agent. This type of preparation makes the agglomeration of NCs to larger entities inevitable and simultaneously decreases the catalytically active surface area. In this work, electocatalysts based on two-dimensional arrays of self-assembled monodisperse Au NCs with a particle size of 8 nm have been fabricated. Their electrocatalytic performance in the electrochemical oxidation reaction of methanol and ethanol was investigated for different pH values. The self-assembly of Au NCs into two-dimensional arrays enables to fabricate electrocatalysts with a high mass activity in alkaline electrolytes for alcohol oxidation reactions.

Colorless powders of orthorhombic Ag[N(CN) 2 ] were synthesized by blending aqueous solutions Ag[NO 3 ] with stoichiometric amounts of Na[N(CN) 2 ] equally dissolved in water. Single crystals of both modifications of Ag[N(CN) 2 ] could be obtained by recrystallizing the powder with aqueous ammonia. Non-isothermal evaporation of the solvent at room temperature within a few hours yielded the orthorhombic modification as the main product crystallizing in the space group Pnma (no. 62) with the unit-cell parameters a = 1612.45(12), b = 361.58(3) and c = 599.02(4) pm ( Z = 4). Upon evaporating the solvent much more slowly, isothermally within a few days, mainly thin hexagonal platelets of the trigonal modification of Ag[N(CN) 2 ] were obtained, crystallizing in the space group P 3 1 21 (no. 152) with the lattice constants a = 359.86(3) and c = 2285.91(17) pm ( Z = 3). Both results corroborate earlier structure determinations, but show higher precision. The vibrational spectra confirm the presence of the dicyanamide anion [N(CN) 2 ] − , but exhibit slight differences to literature data. Differential scanning calorimetry/thermogravimetry (DSC/TG) analyses were performed to further characterize the two modifications.