Selective reductive amination of aldehydes from nitro compounds catalyzed by molybdenum sulfide clusters

Secondary amines are selectively obtained from low value starting materials using hydrogen and a non-noble metal-based catalyst. The reductive amination of aldehydes from nitroarenes or nitroalkanes is efficiently catalyzed by a well-defined diamino molybdenum sulfide cluster in a one-pot homogeneous reaction. The integrity of the molecular cluster catalyst is preserved along the process

A three-dimensional adamantane-like nanoscopic cage built from four iodide-bridged triangular Mo3S7 cluster units

Chemical oxidation of a Mo3S7 cluster featuring catecholate ligands, namely [Mo3S7(Cl4cat)3]2 (Cl4cat = tetrachlorocatecholate), allows the isolation of a unique nanoscopic molecular cage made of four iodide-bridged Mo3S7 clusters as the kinetically favoured produc

Recycling of Cr/Ni/Cu plating wastes as black ceramic pigments

The non-ferrous metal industry, such as Cr/Ni/Cu plating, produces acid sludge which is usually neutralized with lime slurry in batch processes, and the resulting waste is dewatered by vacuum filtration or filter-pressing. Dewatered sludge contains calcium sulphate (CaSO4) coming from the neutralization process, as well as transition metals (Cr, Ni and Cu), oil, grease and suspended solids. In this communication, two residual sludges from Cr/Ni/Cu plating have been dried (110 C) and fired (1100 C), and both dried (gray coloured) and fired powders (black coloured) have been characterized by DTA-TG, XRD and SEMEDX techniques. XRD shows only quartz crystallization in dried samples, while NiCr2O4 chromite spinel and NiO periclase crystallize in fired powders, along with CaSO4 anhydrite and CaSiO3 wollastonite. The powders have been introduced as ceramic pigments into three different conventional glazes: a) a lead bisilicate (PbO.2SiO2) double fire frit (1000 C), b) a double fire frit with low lead content (1000 C), and c) a double fire frit without lead (1050 C). Glazed samples were characterized by UV-Vis-NIR (diffuse reflectance) and CIEL⁄a⁄b⁄ (color parameters). Dried powders induce glaze defects (pin-holing and crawling), but fired powders did not show these faults exhibiting more intense (higher L⁄ ) and yellowish (higher b⁄ ) black colors than the standard spinel

Hydroxylated phosphines as ligands for chalcogenide clusters: Self assembly, transformations and stabilization

© 2017 IUPAC & De Gruyter.This contribution is a documentation of recent advances in the chemistry of chalcogenide polynuclear transition metal complexes coordinated with mono-and di-phosphines functionalized with hydroxo groups. A survey of complexes containing tris(hydroxymethyl)phosphine (THP) is presented. The influence of the alkyl chain in bidentate phosphines, bearing the P-(CH2)x-OH arms, is also analyzed. Finally, isolation and structure elucidation of the complexes with HP(OH)2, P(OH)3, As(OH)3, PhP(OH)2, stabilized by coordination to Ni(0) and Pd(0) centers embedded into chalcogenide clusters, is discussed

Conectividad molecular. Su aplicación a algunas propiedades físico-químicas de un grupo de alcoholes

Se ha aplicado el método de Conectividad Molecular a un grupo de alcoholes, usando como propiedades a correlacionar: la refracción molar, la entalpia de formación y la temperatura de ebullición, y como índices topológicos los de Kier y Hall y los geométricos. Los resultados indican que en estudios de relación estructura-actividad, así como en los de predicción, los índices geométricos son adecuados para propiedades moleculares (Rrn, ∆Hf), mientras que los de Kier y Hall lo son para propiedades molares (Te).Molecular connectlvlty method has been used for studying sorne physico chemical properties, such as molar refraction, heat of formation and boiling point, in a group of alcohols, using the Kier and Hall's and geometrical indices. The results indicate that these are the better for molecular properties (i.e. molar refraction and heat of formation), while Kier and Hall's were for molar properties (i.e. boiling temperature)

Conectividad molecular. Su aplicación a algunas propiedades físico-químicas de un grupo de alcoholes

Molecular connectlvlty method has been used for studying sorne physicochemical properties, such as molar refraction, heat of formation and boiling point, in a group of alcohols, using the Kier and Hall's and geometrical indices. The results indicate that these are the better for molecular properties (i.e. molar refraction and heat of formation), while Kier and Hall's were for molar properties (i.e. boiling temperature).Se ha aplicado el método de Conectividad Molecular a un grupo de alcoholes, usando como propiedades a correlacionar: la refracción molar, la entalpia de formación y la temperatura de ebullición, y como índices topológicos los de Kier y Hall y los geométricos. Los resultados indican que en estudios de relación estructura-actividad, así como en los de predicción, los índices geométricos son adecuados para propiedades moleculares (Rrn,  ∆Hf), mientras que los de Kier y Hall lo son para propiedades molares (Te)

Hybrid Organic/Inorganic Complexes Based on Electroactive Tetrathiafulvalene-Functionalized Diphosphanes Tethered to C3-Symmetrized Mo3Q4 (Q = S, Se) Clusters

A two-step procedure for the preparation of hybrid complexes based on electroactive tetrathiafulvalene (TTF)- functionalized o-P2 diphosphanes (o-P2 = 3,4-dimethyl-3,4-bis(diphenylphosphino)tetrathiafulvalene) and inorganic C3-symmetrized Mo3Q4 (Q = S, Se) clusters, namely, [Mo3S4Cl3(o-P2)3]PF6 ([1]PF6) and [Mo3Se4Cl3(o-P2)3]PF6 ([2]PF6), is reported. Their molecular and electronic structures are also described on the basis of X-ray diffraction experiments and density functional theory (DFT) calculations aimed at understanding the interactions established between both the organic and the inorganic parts. Cyclic voltammograms of compounds [1]PF6 and [2]PF6 display reduction features associated to the Mo3Q4 core and oxidation characteristics due to the TTF skeleton. The oxidation chemistry of [1]PF6 and [2]PF6 in solution is also investigated by means of in situ electrospray ionization (ESI) mass spectrometry, UV-vis, and, electron paramagnetic resonance (EPR) measurements. Upon addition of increasing amounts of NOPF6 (less than 3 equiv), the sequential formation of 1n+ (n = 1-4) species was observed whereas addition of a 3-fold excess of NOPF6 allows to access the three-electron oxidized [Mo3S4Cl3(o-P2)3]4+ (14+) and [Mo3Se4Cl3(o-P2)3]4+ (24+) cations. These 14+ and 24+ cations represent still rare examples of complexes with oxidized TTF-ligands that are remarkably stable either toward diphosphane dissociation or phosphane oxidation. Polycrystalline samples of compound [1](PF6)4 were obtained by oxidation of compound [1]PF6 using NOPF6 which were analyzed by solid state absorption, UV-vis, and Raman spectroscopies

Lattice Distortions Around a Tl+ Impurity in NaI:Tl+ and CsI:Tl+ Scintillators. An Ab Initio Study Involving Large Active Clusters

Ab initio Perturbed Ion cluster-in-the-lattice calculations of the impurity centers NaI:Tl+ and CsI:Tl+ are pressented. We study several active clusters of increasing complexity and show that the lattice relaxation around the Tl+ impurity implies the concerted movement of several shells of neighbors. The results also reveal the importance of considering a set of ions that can respond to the geometrical displacements of the inner shells by adapting selfconsistently their wave functions. Comparison with other calculations involving comparatively small active clusters serves to assert the significance of our conclusions. Contact with experiment is made by calculating absorption energies. These are in excellent agreement with the experimental data for the most realistic active clusters considered.Comment: 7 pages plus 6 postscript figures, LaTeX. Submmited to Phys, Rev.

Water-Soluble Mo3S4 Clusters Bearing Hydroxypropyl Diphosphine Ligands: Synthesis, Crystal Structure, Aqueous Speciation, and Kinetics of Substitution Reactions

The [Mo3S4Cl3(dhprpe)3]+ (1+) cluster cation has been prepared by reaction between Mo3S4Cl4(PPh3)3 (solvent)2 and the watersoluble 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe, L) ligand. The crystal structure of [1]2[Mo6Cl14] has been determined by X-ray diffraction methods and shows the typical incomplete cuboidal structure with a capping and three bridging sulfides. The octahedral coordination around each metal center is completed with a chlorine and two phosphorus atoms of the diphosphine ligand. Depending on the pH, the hydroxo group of the functionalized diphosphine can substitute the chloride ligands and coordinate to the cluster core to give new clusters with tridentate deprotonated dhprpe ligands of formula [Mo3S4(dhprpe-H)3]+ (2+). A detailed study based on stopped-flow, 31P{1H} NMR, and electrospray ionization mass spectrometry techniques has been carried out to understand the behavior of acid−base equilibria and the kinetics of interconversion between the 1+ and the 2+ forms. Both conversion of 1+ to 2+ and its reverse process occur in a single kinetic step, so that reactions proceed at the three metal centers with statistically controlled kinetics. The values of the rate constants under different conditions are used to discuss on the mechanisms of opening and closing of the chelate rings with coordination or dissociation of chloride

Ab Initio Calculation of the Lattice Distortions induced by Substitutional Ag- and Cu- Impurities in Alkali Halide Crystals

An ab initio study of the doping of alkali halide crystals (AX: A = Li, Na, K, Rb; X = F, Cl, Br, I) by ns2 anions (Ag- and Cu-) is presented. Large active clusters with 179 ions embedded in the surrounding crystalline lattice are considered in order to describe properly the lattice relaxation induced by the introduction of substitutional impurities. In all the cases considered, the lattice distortions imply the concerted movement of several shells of neighbors. The shell displacements are smaller for the smaller anion Cu-, as expected. The study of the family of rock-salt alkali halides (excepting CsF) allows us to extract trends that might be useful at a predictive level in the study of other impurity systems. Those trends are presented and discussed in terms of simple geometric arguments.Comment: LaTeX file. 8 pages, 3 EPS pictures. New version contains calculations of the energy of formation of the defects with model clusters of different size