Search results for "Metals"

Rhodium catalyzed oxidative coupling of salicylaldehydes with diazabicyclic olefins: a one pot strategy involving aldehyde C–H cleavage and π-allyl c…

2013

An efficient one pot strategy for the synthesis of cyclopentene fused chromanone derivatives through the direct oxidative coupling of salicylaldehydes with bicyclic olefins in the presence of a rhodium-copper catalyst system is described. This is the first report on the ring opening-ring closing of bicyclic hydrazines via metal catalyzed oxidative coupling reaction.

DELAYED ELECTRON EMISSION OF NEGATIVELY CHARGED TUNGSTEN CLUSTERS

1996

The delayed electron emission of negatively charged tungsten clusters has been investigated on a time scale from 1 to 500 ms. After being stored in a Penning trap clusters ions [Formula: see text] were heated via multiphoton absorption (hν=1.81 eV). In contrast to alkali and coinage metals no photofragmentation could be detected. Instead, for all cluster sizes studied so far only a decrease in the initial ion intensity as a function of time after excitation was observed. This decrease is not caused by ion loss from the trap, but has to be attributed to neutralization via delayed electron emission. The presented results strongly suggest that this process can be viewed as “thermionic emissio…

Multivariate statistical analysis of heavy metals and physico-chemical parameters in the groundwater of Karak District, Khyber Pakhtunkhwa, Pakistan

2021

Groundwater heavy metal pollution is a major concern all around the world. For the assessment of heavy metals and physico-chemical characteristics. groundwater samples were collected from different locations of the Karak District, Pakistan. With the help of the global information system device (GIS), groundwater samples were collected and studied from 47 locations. The present study focused on the water table (WT), water source depth (WSD), pH, electrical conductivity (EC), dissolved oxygen (DO), total dissolved solids (TDS), lead (Pb(II)), silver (Ag(I)), iron (Fe(II)) and chromium (Cr(VI)) parameters. Heavy metals were analyzed by the Atomic Absorption Spectrophotometer (AAS). The Pearson…

Influence of Mn site doping on electrical resistivity of polycrystalline La1-yAyMn1-xBxO3 (A=Ba, Sr; B=Cu, Cr, Co) Manganites

2008

We have the measured electrical resistivity of La1-yBayMn1-xCuxO3 (0.17?y?0.30; 0.04?x?0.10), La1-ySryMn1-xCrxO3 and La1-ySryMn1-xCoxO3 (0.270?y?0.294; 0.02?x?0.10) polycrystalline samples in the 25-325 K temperature range. The increase of Mn site doping concentration leads to an increase of the electrical resistivity of the samples and the appearance of a ?double-peak? structure in the electrical resistivity versus temperature graphs. The first peak represents the insulator-metal transition in vicinity of the paramagnetic-ferromagnetic transition (TC). We have found that the intensity of the second peak increases with an increase of concentration of Mn substituents, due to the hole scatter…

The effect of ash and compost on the content and bioaccumulation of selected heavy metals

2019

Abstract Therefore the carried out study aimed at determination of the effect of high-calcium brown coal ash and compost being produced from municipal sewage sludge on the content and bioaccumulation of heavy metals in potato tubers, wheat grains and rapeseeds during a three-year period. Rapeseeds contained most Cd whereas wheat rains less. Potato tubers, wheat grains and rapeseeds contained more Mn, Ni and Zn in the fertilization objects with municipal sewage sludge with or without coal ash and compared to those where calcium carbonate or coal ash had been introduced into the soil at a dose corresponding to 1.5 Mg CaO · ha–1 at the beginning of this study. Differences in the Mn, Ni and Zn …

Zawartość metali ciężkich w kompostach z odpadów jako czynnik ograniczający ich wykorzystanie do celów nawozowych

2009

Reactivity of bis(cyclohexylammonium) 4-nitrophenylphosphate with SnMe3 Cl. X-ray structure of 4-NO2 C6 H4 PO4(SnMe3)2·H2 O

2014

The reaction of bis(cyclohexylammonium) 4-nitrophenylphosphate with Me3 SnCl (1:2) under reflux in ethanol yielded the title compound 4-NO2 C6 H4 PO4(SnMe3)2H2 O (1). The X-ray crystallographic analysis achieved on single crystals obtained by slow evaporation at room temperature revealed the formation of an unexpected supramolecular coordination network. The elementary building block can be viewed as two Me3 Sn moieties linked by a bridging 4-nitrophenylphosphate ligand. The two tin atoms are five-coordinated and describe a trans-Me3 SnO2 geometry in a trigonal bipyramidal arrangement. However, the Sn atoms are distinct, exhibiting two different environments. Thus, one is linked to two axia…

An Overview on the Performance of 1,2,3-Triazole Derivatives as Corrosion Inhibitors for Metal Surfaces

2021

This review accounts for the most recent and significant research results from the literature on the design and synthesis of 1,2,3-triazole compounds and their usefulness as molecular well-defined corrosion inhibitors for steels, copper, iron, aluminum, and their alloys in several aggressive media. Of particular interest are the 1,4-disubstituted 1,2,3-triazole derivatives prepared in a regioselective manner under copper-catalyzed azide-alkyne cycloaddition (CuAAC) click reactions. They are easily and straightforwardly prepared compounds, non-toxic, environmentally friendly, and stable products to the hydrolysis under acidic conditions. Moreover, they have shown a good efficiency as corrosi…

Organotin(IV) selenate derivatives – Crystal structure of [{(Ph 3 Sn) 2 SeO 4 } ⋅ CH 3 OH] n

2021

Abstract Crystallization of [(Ph3Sn)2SeO4] ⋅ 1.5H2O in methanol leads to the formation of [{(Ph3Sn)2SeO4} ⋅ CH3OH] n (1) which constitutes a new specimen of organotin(IV) selenate derivatives. In the solid state, complex 1 is arranged in polymeric zig-zag chains, composed of alternating Ph3Sn and SeO4 groups. In addition, pendant Ph3Sn ⋅ CH3OH moieties are branched along chains according to a syndiotactic organization and via Sn-O-Se connections. From a supramolecular point of view, intermolecular hydrogen bonds established between the selenate groups (uncoordinated oxygen) and the hydroxyl functions (CH3OH) of the pendant groups link the chains together.

Synthesis, spectroscopic study, and crystal structure of a new organotin(IV) selenate derivative

2018

Abstract The polymeric organotin(IV) selenate complex [(Me3Sn)3(SeO4)(OH)]n (1) has been isolated as single crystals from the reaction of [(Me2NH2)2SeO4] and Me3SnCl in methanol. In the solid state, compound 1 was characterized by X-ray diffraction analysis, Fourier transform-infrared spectroscopy, and elemental analysis. 1 crystallizes in the orthorhombic system space group Pbca with a=11.0231(2) Å, b=16.3461(3) Å, c=20.9945(4) Å, α=β=γ=90°, V=3782.89(12) Å3, and Z=8. Its structure can be described as a polymeric zigzag chain based on Me3Sn moieties linked by tridentate selenate anions. Pendant (Me3Sn)2OH groups are also connected to the chain, according to a syndiotactic organization, and…