Volume 79, Issue 2-3

The crystal-chemical relationship of the cubic Laves phase MgCu 2 (space group F d 3 ‾ $d\overline{3}$ m , cF 24) with the ternary phases Cd 2 Cu 3 In, Na 2 Au 3 Al, Mg 2 Rh 3 P, Li 2 Pd 3 B, Ag 2 Pd 3 S, Cu 3 Pt 2 B, Mo 3 Al 2 C, Mo 3 Ni 2 N, and V 3 Ga 2 N (subgroup P 4 1 32, cP 24, dca ) is discussed based on a group-subgroup scheme. The course of the lattice parameters and the free positional parameters show substantially different distortions and thus clear differences in chemical bonding, classifying these phases as isopointal rather than isotypic (usually they are all assigned to the Mo 3 Al 2 C type). The group-subgroup scheme further shows that the β -Mn and SrSi 2 structures are vacancy-ordered variants of the cP 24, dca phases. The structures of Mn 3 IrSi and LaIrSi (space group types P 2 1 3; translationengleiche subgroups) are their ternary ordered versions.

In the present study, 12-tungestocobaltic acid, H 5 CoW 12 O 40 , was immobilized on nano silica from rice husk (CoW@NSiO 2 ) to develop a novel, efficient, heterogeneous and recyclable nano catalyst for the synthesis of β -enaminones. It is apparent from acidity and cyclic voltammetric measurements that, the catalyst is electroactive and undergoes reversible redox transitions, as well as it is contains strong acid sites and mobile protons. As evidenced from mechanistic investigations, CoW@NSiO 2 can catalyze the synthesis of β -enaminones with two simultaneous ways: electron transfer and Brønsted acid mechanisms. In order to confirm the synthesis of enaminones through simultaneous mechanisms of electron transfer and acidity, the model reaction was carried out in the presence of K 5 Co as an electroactive catalyst and CoW@NSiO 2 with electron scavenger as an acid catalyst. The results showed that the reaction proceeded simultaneously through both mechanisms. There is evidence that the electron transfer property of this catalyst is most pronounced in this type of organic reactions. The catalyst demonstrated outstanding performance, and the methodology proved to be versatile, yielding excellent results across a wide range of substrates. It is worth mentioning that aliphatic amines were well-tolerated in the process and produced β -enaminone compounds with excellent yields and short reaction times. Also, reactions with dimedone, a cyclic 1,3-diketone, delivered moderate product yields. Additionally, the catalyst showed remarkable recyclability, maintaining its activity for a minimum of five consecutive cycles without any noticeable decline. Notably, the cyclic voltammetric and acidity measurements revealed that the catalyst’s electron transfer property and Brønsted acidity remained unchanged after five runs.

A Metal-Organic Framework (MOF) based on a tricarboxylic acid ligand (H 3 L = biphenyl-2,4′,5-tricarboxylic acid), namely [Cd 3 (L) 2 (H 2 O) 4 ] ( 1 ), had been prepared and characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction (PXRD), thermogravimetric analyses (TGA), and single-crystal X-ray diffraction. Fluorescence studies showed that 1 has high quenching efficiency for testing acetone and Fe 3+ ions in aqueous systems. Therefore, it can be used as a new type of fluorescence probe to detect solvent molecules and metal ions in water.

In the present study, chiral 2-(4-substiuted phenyl)amino-5-[1-(4-substituted benzenesulphonamido)alkyl]-1,3,4-thiazdiazoles 5a – x were synthesized from enantiopure l- amino acids in a multistep sequence. The starting acids were reacted with arylsulphonyl chlorides to produce N -arylsulfonyl amino acids 1a – h , followed by esterification to obtain the corresponding esters 2a – h . Treatment of esters with hydrazine hydrate afforded the corresponding hydrazides 3a – h . The coupling of hydrazides with aryl isothiocyanates followed by cyclization gave the target thiadiazoles 5a – x in good yields. The new synthesized compounds were assayed against HIV-1 and HIV-2 in MT-4 cells using MTT assay. Compounds 5s , 5v and 5w showed IC 50 values of > 1.58, >1.98 and > 2.04 μ m with SI > 1, respectively, indicating that these compounds were cytotoxic at concentrations values of 1.58, 1.98 and 2.04 μ m , respectively.

A novel 1D Mn(II) coordination polymer, namely, [Mn 3 (bpz) 2 (MeCN) 2 Cl 6 ] n ( 1 ) was synthesized by a solvothermal method based on bpz and MnCl 2 , where bpz is di(1 H -pyrazol-1-yl)methane. The X-ray diffraction data show that the crystal structure of complex 1 is a one-dimensional polymer with two different coordination modes of the Mn(II) ions. The structure was modelled with Density Functional Theory (DFT) calculations and the intermolecular interactions were analyzed using the Hirshfeld surface method.

The electron density distribution (EDD) of a plant cyclic nonapeptide of orbitide type was studied. Crystal X-ray diffraction data was obtained from the Cambridge Structural Database (CSD) and refitted using scattering factors of the invariom library, thereby providing aspherical electron density. Bond topological, atomic properties and molecular surfaces (electrostatic potential and Hirshfeld surfaces) were derived. The partial double bond character of the peptide bond was confirmed by the ellipticity ε  = 0.25. For eight N–H⋯O hydrogen bonds, atomic charges of contributing atoms differ depending on the type of the accepting oxygen atom. Atomic charge differences between negative main and positive side chains of this nonapeptide result in characteristic features of the electrostatic potential, which shows a positive isosurface around the molecule leading to repulsive interactions in the solid state structure. Weak intermolecular interactions are indicated by insignificant ED concentrations on the Hirshfeld surface except for weak signals at sites of intermolecular N–H⋯O and C–H⋯O hydrogen bonds.

The quasi-binary system YbMg 2 -YbIn 2 was studied around the equiatomic composition. In contrast to the ordered rare earth ( RE ) phases RE MgIn (ZrNiAl type), ytterbium forms phases with different structures and pronounced Mg/In mixing ( M sites). The structures of YbMg 0.75 In 1.25 (CaLiSn type, P 3 m 1, a = 501.95(7), c = 1087.3(2) pm, wR 2 = 0.0490, 790 F 2 values, 32 variables) and Yb 6 Mg 6.41 In 5.59 (Yb 6 Ir 5 Ga 7 type, P 6 3 / mcm , a = 1060.77(14), c = 970.27(16) pm, wR 2 = 0.0484, 701 F 2 values, 26 variables) were refined from single-crystal X-ray diffractometer data. YbMg 0.75 In 1.25 is an AlB 2 superstructure with a tripling of the subcell. The magnesium and indium atoms form three differently puckered layers of M 6 hexagons. The Yb 6 Mg 6.41 In 5.59 structure is derived from the hexagonal Laves phase YbMg 2 (MgZn 2 type, P 6 3 / mmc ). A klassengleiche symmetry reduction leads to four crystallographically independent M sites for the rows of corner- and face-sharing tetrahedra which allow a composition close to the equiatomic one. The M – M distances in both structures cover the broad range from 289 to 331 pm, comparable to the sums of the covalent radii. Temperature dependent magnetic susceptibility studies of the polycrystalline YbMg 0.75 In 1.25 and Yb 12 Mg 13 In 11 samples indicate Pauli paramagnetism with room temperature values of 2.8(1) × 10 −3  emu mol −1 (YbMg 0.75 In 1.25 ) and 5.2(1) × 10 −3  emu mol −1 (Yb 12 Mg 13 In 11 ).

The reaction of chlorodimethylphosphane with dilithiated bis(ethynyldimethylsilyl)methane leads to the corresponding bis[(dimethylphosphanylethynyl)dimethylsilyl]methane ( 1 ) which reacts readily with chloroauric acid in the presence of a reductant to form its dinuclear chlorogold(I) complex ( 2 ). The terminal chloride units of this compound can be substituted by reaction with nucleophiles. Furthermore, the metallophilic host functionality of the dinuclear complex 2  towards metallophilic atoms such as copper, silver, and thallium was tested. The crystal structure of bis[(dimethylphosphanylethynyl)dimethylsilyl]methane-digold(I) dichloride ( 2 ) is presented, which shows chains of the molecules aggregated by intermolecular aurophilic contacts.

The Lu 3 Co 2 In 4 -type stannides RE 3 Ir 2 Sn 4 ( RE = Y, Sm, Gd–Tm, Lu) were synthesized from the elements by arc-melting and subsequent annealing sequences in sealed silica ampoules. For a more comprehensive phase analytical study, the isotypic stannide Sm 3 Rh 2 Sn 4 and the ZrNiAl-type stannides DyIrSn and LT-YIrSn were also obtained. The polycrystalline samples were characterized through their X-ray powder patterns. The structures of DyIrSn and Gd 3 Ir 2.63(2) Sn 3.37(2) (ZrNiAl type, space group P 6‾2 m ), Sm 3 Ir 2.52(2) Sn 3.48(1) , Gd 3 Ir 2.49(1) Sn 3.51(1) and Tm 3 Ir 2.20(3) Sn 3.80(3) (Lu 3 Co 2 In 4 type, space group P 6‾) were refined from single-crystal X-ray diffractometer data, revealing residual Ir/Sn disorder in the low-symmetry variants. The RE 3 Ir 2 Sn 4 stannides are derived from the equiatomic stannides RE IrSn (≍ RE 3 Rh 3 Sn 3 ) by partial Ir/Sn substitution. The symmetry reduction from space group P 6‾2 m to P 6‾ is forced by the Ir/Sn ordering within the RE 6 trigonal prisms. The new Sn2 position shows the rare motif of a trigonal planar tin coordination with 289 pm Sn2–Sn1 distances (data for Gd 3 Ir 2.49(1) Sn 3.51(1) ). 119 Sn Mössbauer spectra confirm the two crystallographically independent tin sites in Tm 3 Ir 2 Sn 4 and the structural disorder in Gd 3 Ir 2 Sn 4 .

Polycrystalline diguanidinium hexafluoridogermanate (IV) was obtained by co-precipitation from solutions of diguanidinium carbonate and germanium dioxide in 48 % hydrogen fluoride. The [C(NH 2 ) 3 ] 2 [GeF 6 ] structure was refined from single crystal X-ray diffractometer data: [C(NH 2 ) 3 ] 2 [TiF 6 ] type, C 2/ m , a = 1276.67(8), b = 732.70(5), c = 616.37(5) pm, b = 114.497(5)°, w R = 0.0700, 1033 F 2 values, 53 variables. The trigonal planar [C(NH 2 ) 3 ] + cations and the octahedral [GeF 6 ] 2− anions are condensed to double layers through strong H⋯F hydrogen bonds (208–213 pm H⋯F). The centers of gravity of the two building units have an antifluorite-like topology.