Periodicity of Single-Molecule Magnet Behaviour of Heterotetranuclear Lanthanide Complexes across the Lanthanide Series: A Compendium.

Acetato-bridged palladium-lanthanide tetranuclear heterometallic complexes of the form [Pd2 Ln2 (H2 O)2 (CH3 COO)10 ]⋅2 CH3 COOH [Ln2 =Ce2 (1), Pr2 (2), Nd2 (3), Sm2 (4), Tb2 (5), Dy2 (6), Dy0.2 Y1.8 (6''), Ho2 (7), Er2 (8), Er0.24 Y1.7 (8''), Tm2 (9), Yb2 (10), Y2 (11)] were synthesised and characterised by experimental and theoretical techniques. All complexes containing Kramers lanthanide ions [Ln3+ =Ce (1), Nd (3), Sm (4), Dy (6), DyY (6''), Er (8), ErY (8''), Yb (10)] showed field-induced slow magnetic relaxation, characteristic of single-molecule magnetism and purely of molecular origin. In contrast, all non-Kramers lanthanide ions [Ln3+ =Pr (2), Tb (5), Ho (7), Tm (9), Y3+ (11) is diamagnetic and non-lanthanide] did not show any slow magnetic relaxation. The variation in the electronic structure and accompanying consequences across the complexes representing all Kramers and non-Kramers lanthanide ions were investigated. The origin of the magnetic properties and the extent to which the axial donor-acceptor interaction involving the lanthanide ions and an electron-deficient d z 2 orbital of palladium affects the observed magnetic and electronic properties across the lanthanide series are presented. Unique consistent electronic and magnetic properties of isostructural complexes spanning the lanthanide series with properties dependent on whether the ions are Kramers or non-Kramers are reported

Kinetics and Mechanism of Electron Transfer Reaction of an Adipato Bridged Iron(III)-Salen Complex with Dithionite Ion in Perchloric Acid Medium

Redox kinetics of the reaction of an adipato bridged iron(III)-salen complex, [(Fe(salen))2adi] with dithionite ion, S2O42–, was investigated in perchloric acid at I = 0.05 mol dm–3 (NaClO4) and T = 29 ± 1 °C. Spectrophotometric titrations indicated consumption of one mole of S2O42– per mole of [(Fe(salen))2adi] reduced. Under pseudo-first order conditions of [S2O42–] above ten-fold excess of concentration of [(Fe(salen))2adi], observed rates increased with increase in [S2O42–] and second order rate constants were fairly constant (0.285 ± 0.01 dm3 mol–1 s–1) indicating first order dependence of the rate on [(Fe(salen))2adi]. A plot of logkobs versus log[S2O42–] was linear and gave a slope of 1.0 indicating first order dependence of the rate on [S2O42–]. The reaction rate increased with increase in [H+] within 3 × 10–3 mol dm–3 ≤ [H+] ≤ 14 × 10–3 mol dm–3. The reaction was unaffected by variation of ionic strength and dielectric constant of the medium. Addition of anion and cation did not catalyze the reaction. The reaction has been analyzed on the basis of an inner-sphere mechanism mediated by proton transfer

Geochemical, ecological, and health risk assessment of potentially toxic elements (PTEs) in the surrounding soil of a cement plant

Abstract Cement plants are the major anthropogenic sources of potentially toxic elements (PTEs), which are generated from the processing of raw materials and combustion of fossil fuels. This study determined the PTE concentration and assessed the geochemical, ecological, and health risks associated with the activities in the Ashaka cement plant, Bajoga, Nigeria. Soil samples were collected between 2019 and 2020, and analyzed by ICP-OES for 20 PTEs. The data obtained were statistically evaluated for descriptive and inferential statistics. The mean concentrations of PTEs were in the declined order of Al > Fe > Mn > Zn > Ti > Ba > Sr > Pb > Cu > V > Cr > Ni > As > Sc > Mo > Hg > Cd > Se > Sb > Co. Multivariate analysis revealed that the main sources of PTEs might be related to anthropogenic activities from the cement plant. The geochemical load index (GLI) values obtained range from unpolluted to moderate. The ecological risk ranged from 4.74 × 10–3 to 8.00 × 100, and the overall risk index indicated low contamination for the investigated elements. The hazard index (HI) was < 1, suggesting non-probable non-carcinogenic effects. However, children were more susceptible to risk than adults, and the cancer risk (CR) values of Cd for children and adults were higher than the threshold level of 1.0 × 10–4, which suggests probable development of cancer risk for residents

N′-[(4Z)-1-(3-Methyl-5-oxo-1-phenyl-4,5-dihydro-1H-pyrazol-4-ylidene)hexyl]benzenesulfonohydrazide

In the title compound, C22H26N4O3S, the dihedral angle between the pyrazoloneand phenyl rings is 21.73 (4)°. The benzensulfonohydrazide group adopts a gauche conformation about the N—N vector. The C—N—N—S torsion angle is −109.88 (13)°. The molecule exists as the enamine tautomeric form (C=C—NH). An intramolecular N—H...O=C hydrogen bond occurs. In the crystal, molecules are linked by pairs of N—H...O=C hydrogen bonds, forming centrosymmetric dimers

N-(2-Chloroethyl)morpholine-4-carboxamide

The title compound, C7H13ClN2O2, synthesized by the reaction of 2-chloroethyl isocyanate and morpholine, crystallizes with four molecules in the asymmetric unit, which have similar conformations and comprise two pairs each related by approximate non-crystallographic inversion centres. Two of them have a modest orientational disorder of the 2-chloroethyl fragments [occupancy ratio of 0.778 (4):0.222 (4)]. In the crystal, molecules are linked by N—H...O=C hydrogen bonds, forming three crystallographically different kinds of infinite hydrogen-bonded chains extending along [001]

Crystal structure of N′-[(1E)-1-(6-methyl-2,4-dioxo-3,4-dihydro-2H-pyran-3-ylidene)ethyl]benzenesulfonohydrazide

In the title compound, C14H14N2O5S, the molecule exists in the enamine (C=C—NH) tautomeric form. The hydrazone fragment derived from the 3-acetyl-4-hydroxy-6-methyl-2H-pyran-2-one moiety is approximately planar, with a maximum deviation of 0.1291 (11) Å for the N atom bound to the S atom of the benzensulfonohydrazide group. The latter adopts a gauche conformation relative to the hydrazone N—N bond, with an N—N—S angle of 113.54 (10)°. There is an intramolecular N—H...O=C hydrogen bond that stabilizes the tautomeric form. In the crystal, molecules are linked by N—H...O=C hydrogen bonds into chains extending parallel to [100]

A Novel Schiff Base of 3-acetyl-4-hydroxy-6-methyl-(2H)pyran-2-one and 2,2'-(ethylenedioxy)diethylamine as Potential Corrosion Inhibitor for Mild Steel in Acidic Medium

The corrosion inhibition activity of a newly synthesized Schiff base (SB) from 3-acetyl-4-hydroxy-6-methyl-(2H)-pyran-2-one and 2,2'-(ethylenedioxy)diethylamine was investigated on the corrosion of mild steel in 1 M HCl solution using potentiodynamic polarization and electrochemical impedance spectroscopic techniques. Ultraviolet-visible (UV-vis) and Raman spectroscopic techniques were used to study the chemical interactions between SB and mild steel surface. SB was found to be a relatively good inhibitor of mild steel corrosion in 1 M HCl. The inhibition efficiency increases with increase in concentration of SB. The inhibition activity of SB was ascribed to its adsorption onto mild steel surface, through physisorption and chemisorption, and described by the Langmuir adsorption model. Quantum chemical calculations indicated the presence of atomic sites with potential nucleophilic and electrophilic characteristics with which SB can establish electronic interactions with the charged mild steel surface