Inorganic Chemistry Research
Volume:6 Issue: 1, Jun 2022

This study aims to prepare di-brominated Mn(III) Salophen, [MnSalBr], grafted onto CoFe2O3/graphene oxide (CFGO) via a covalent bond. The characterization of this heterogeneous catalyst (CFeGO@MnSalBr) was carried out by FTIR, DR UV-Vis, XRD, FESEM, EDX spectroscopy, elemental scanning mappings, thermogravimetric analysis (TGA/DTG), and nitrogen adsorption-desorption isotherm. The amount of manganese salophen loading on the CFG support was determined by inductively coupled plasma spectroscopy (ICP). At room temperature, the as-prepared catalyst was applied to oxidize olefins with H2O2 as a green oxidant. The result confirmed this catalyst's high catalytic reactivity and excellent selectivity in the epoxidation of various alkenes. The effects of different factors such as the kind of solvent and oxidant, amount of catalyst and oxidant, and reaction time were also studied. Furthermore, the GO-bound Mn salophen was reused for several runs without any noticeable activity loss or selectivity.

Nano-magnetic ferrite ZnFe2O4 among other magnetic nanoparticles include Fe2O3, Fe3O4, Ni(0.7)Zn(0.3)Fe2O4 and Mn(0.7)Zn(0.3)Fe2O4 was explored as an efficient catalyst for the synthesis of various 4H-Chromenes and 4H-Pyrano[2,3-c]pyrazoles in EtOH/H2O (2:1) via an easy and green procedure. The desired products were obtained in high yields via a three-component reaction between aromatic aldehydes with malononitrile and 5,5-dimethyl-cyclohexane-1,3-dione or 3-methyl-1-phenyl-2-pyrazolin-5-one at room temperature. The structure of this catalyst was fully characterized via Fourier transform infrared spectroscopy, XRD, SEM, TEM, EDAX, and VSM. The employed nanocatalyst was easily recovered using a magnetic field and reused ten times (in subsequent runs) without observation a significant decrease in activity.

Two new Mn(II) coordination compounds, [Mn(HL)(NCS)(Cl)(CH3OH)] (1) and [Mn4(L)2(µ-N3)4(N3)0.5(Cl)1.5(CH3OH)2]·3.5(CH4O) (2), were synthesized and characterized by elemental analysis and spectroscopic methods where HL is bis-[(E)-N'-(methyl(pyridin-2-yl)methylene)]thiocarbohydrazide. The compounds were synthesized by the reaction of HL, MnCl2∙4H2O and KSCN (in 1) or NaN3 (in 2) with 1:2:4 molar ratios in methanol. The crystal structures of 1 and 2 were determined by single-crystal X-ray diffraction analysis which revealed that 1 is a mononuclear Mn(II) coordination compound while 2 is an azido bridged tetranuclear Mn(II) cluster. In both 1 and 2 the Mn(II) ions have octahedral coordination environment which is created by coordination of nitrogen and sulfur atoms from thiocarbohydrazone ligand. In compound 1 the ligand acts as a neutral tridentate N2S-donor ligand while in 2 it acts as mononegative N4S-donor ligand. In 2, the azide anions act as both terminal and bridging ligand and four Mn(II) ions are connected together by four bridging azide ligands. Furthermore, the Mn(II) ions in 2 are also connected together by sulfur atoms of the thiocarbohydrazone ligand. The FT-IR spectra of 1 and 2 show the characteristic bands of SCN– and N3– anions, respectively. The analysis indicated that the pseudo-halide SCN– and N3– anions have considerable effect on the structure and nuclearity of the coordination compounds. The formation of tetranuclear cluster in the presence of azide anion was attributed to its higher ability to act as bridging group and also its relatively basic character which influence on the coordination mode of the thiocarbohydrazone ligand.

Herein, the catalytic performance of [Cu(3-hydroxy-2-naphtoate)2].4H2O complex has been examinated in synthesis of polyhydroquinoline and 2,3-dihydroquinazoline-4(1H)-one derivatives. The catalytic reactions have been carried out in solvent-free conditions. The obtained results have showed that the complex has high catalytic activity, so that the desired products were obtained in good to high yields. Moreover, the investigated catalyst was found to be reusable, which could be achieved after 3rd run with a considerable catalytic activity.

Methadone is a synthetic drug utilized to manage chronic pain and treat opioid maintenance. The drug enters water bodies as a contaminant due to its widespread use in various communities, which is usually not removed by wastewater treatment plants. Therefore, a photodegradation procedure was developed to degrade and remove methadone in water samples. A hydrothermal strategy was applied to prepare three photocatalysts based on Cr2O3 nanoparticles, a polyoxometalate (phosphotungstic acid), and a hybrid material (Cr2O3 nanoparticles encapsulating phosphotungstic acid). The effective factors, such as methadone concentration, pH, photocatalyst amount, and H2O2 concentration, in the photodegradation method for each catalyst were optimized by an experimental design using a central composite design. Under the optimum conditions, the kinetic model and maximum photodegradation efficiency of the process for each catalyst were studied to compare their ability for methadone degradation. The maximum photodegradation efficiencies for methadone degradation using phosphotungstic acid and Cr2O3 nanoparticles were 82.00 and 77.18% for 120 min. In comparison, the maximum photodegradation efficiency in the presence of Cr2O3 nanoparticles encapsulating phosphotungstic acid was 90.11% for 100 min. The results indicated the new hybrid material prepared from encapsulating phosphotungstic acid with Cr2O3 nanoparticles, leading to a proper increase in the methadone degradation and reducing the degradation time significantly.

Tetradentate platinum(II) emitters are a research topic of great interest since they can be used as dopants for organic light emitting diodes (OLEDs). These compounds benefit from the square-planar geometry of platinum(II) and the rigidity of the tetradentate ligand. Cyclometallated ligands are particularly appealing since they are thermally stable and display a high ligand field splitting which favors efficient emission. The photophysical properties of these complexes can be tuned by structural modifications, introduction of substituents or control of the intermolecular interactions. Several of the studied compounds have been successfully tested for electroluminescent devices. An overview of the advances reported in this field for the last five years is presented in this work.

3-Ethoxy salicylaldehyde on reaction with 1,2-phenylenediamine and 2-aminophenol yielded heterocyclic ligands (HLBIZ and HLBOZ) under ultrasonic irradiation in ethanol solvent. The reaction of these ligands with copper(II) acetate monohydrate salt led to the related Cu(L)2 complexes in methanol solvent. FT-IR, 1H & 13C NMR, and elemental analysis were used to investigate the structures of the synthesized ligands, while the copper(II) complexes were characterized by CHN analysis and FT-IR spectroscopy. The imino nitrogens and phenolic oxygens are involved in the coordination of the ligands to the Cu2+ ions to generate the complex. The parameters estimated by DFT at the B3LYP/Def2-TZVP level of theory show that the theoretical values are consistent with the experimental findings.

The chemistry of bis[dimethylplatinum(II)] complexes of four ditopic ligands based on anthracene [1,8-C14H8(N=CH-2-C5H4N)2, L1, and 1,8-C14H8(CC-4-C6H4-N=CH-2-C5H4N)2, L2] or 2,7-di-t-butyl-9,9-dimethyl-xanthene [4,5-C23H28O(N=CH-2-C5H4N)2, L3, and [4,5-C23H28O(C(=O)NH-4-C6H4-N=CH-2-C5H4N)2, L4] backbones. Each complex [(PtMe2)2(L1)] - [(PtMe2)2(L4)] reacted with MeI to give the corresponding platinum(IV) complex [(PtIMe3)2(L1)] - [(PtIMe3)2(L4)] as a mixture of two isomers which equilibrated slowly at room temperature.  The complex [(PtMe2)2(L3)] also underwent oxidative addition with PhCH2Br, I2 or HgBr2 to give [(PtBrMe2CH2Ph)2(L3)], [(PtI2Me2)2(L3)] or [(PtBrMe2)2(Hg)(L3)] respectively, the last containing a Pt-Hg-Pt unit.  Finally, the complexes [(PtIMe3)2(L3)] and [(PtIMe3)2(L4)] reacted with silver triflate and pyrazine (C4H4N2) to give the complexes [(PtMe3)2(C4H4N2)(L3)][O3SCF3]2 and [(PtMe3)2(C4H4N2)(L4)][O3SCF3]2, respectively, each of which contains a bridging pyrazine ligand.

In this work, two Cu(II) complexes containing 5-amino-1-R-1H-benzimidazol-4-yl)(4-chloro)phenylmethanone hydrazones ligands were synthesized and their spectral characterization, DFT calculations, and catalytic activity were reported. New heterocyclic hydrazone ligands were prepared by the reaction of o-amino-ketones with hydrazine hydrate in high yield. Structural assignments of new compounds were based on their microanalytical and spectral data and formula [Cu(L)2(H2O)2](SO4) was suggested for complexes. Moreover, to gain a further insight into the geometry of synthesized complexes, the DFT calculations were carried out at the B3LYP/6-311+G(d,p) level of theory. The catalytic activity of Cu(II) complexes as heterogeneous catalysts were also investigated in the synthesis of biologically active compound 3,4-dihydropyrimidin-2(1H)-one C5 ester, via classical Biginelli reaction followed by trans-esterification reaction. The results confirmed that the current method formed the products at the lower reaction time and high yields, which might as a result of the enhanced reactivity of the reactants on the surface sites of Cu(II) complexes.

A new palladium(II) complex is synthesized via the treatment of unsymmetrical tetradentate Schiff base (H2LUns) with Pd(CH3COO)2. An analytical technique like combustion analysis for the estimation of C, H, and N and other spectroscopic techniques such as FT-IR and 1H NMR were used to elucidate the structural confirmation of the synthesized complex. Furthermore, the theoretical parameters of the optimized structures calculated by the DFT employing the B3LYP/Def2-TZVP level of theory were carried out to correlate the calculated findings with the actual data obtained experimentally. The spectroscopic and theoretical data findings revealed that the ligand is coordinated via phenolic oxygen and imine nitrogen atoms. Moreover, the catalytic activity of the palladium(II) complex was studied in the Suzuki-Miyaura cross-coupling reactions (SMCR).

The natural diatomite nanoparticles (Dt) were covalently functionalized by 3-(trimethoxysilyl)-propylamine (MSPA) and salicylaldehyde to support VO(acac)2 and MoO2(acac)2 precursor complexes. The prepared compounds were characterized by FT-IR, PXRD, SEM, EDX, ICP, and BET techniques. Then they were used to catalyze the heterogeneous epoxidation of cis‐cyclooctene as a model alkene using tert-butyl hydroperoxide (TBHP). Various parameters that affect catalytic efficiency were investigated, and the optimized experimental conditions were successfully used for the epoxidation of other linear and non-linear alkenes. The important advantages of these new catalytic systems are their simple preparation, low catalyst loading, and high product yield. Moreover, these catalysts can be used up to three times for an efficient epoxidation of cis‐cyclooctene.

A density functional theory (DFT) study of the reaction of [Me2Pt(µ-NN)(µ-dppm)PtMe2] (1) (NN = phthalazine, dppm = bis(diphenylphosphino)methane) with two equivalents of iodomethane in acetone (A) and benzene (B) reveals a mechanism in agreement with spectrocopic and kinetic data reported earlier by Rashidi and coworkers, for which computation permits additional insights. Following initial oxidation at one platinum(II) centre to form mixed valence outer-sphere ion-pairs containing a PtII→PtIV interaction, [Me3Pt(+)(µ-NN)(µ-dppm)PtMe2·I(-)] (6A, 7B), two competing mechanisms are found for the second oxidative addition at the remaining platinum(II) centre. In one mechanism (Path I), a rearrangement of intermediate 6A and 7B to form [Me3Pt(κ1-NN)(µ-dppm)(µ-I)PtMe2] (2aA, 2aB) occurs prior to oxidative addition giving, after subsequent steps, outer-sphere ion-pairs [Me3Pt(κ1-NN)(µ-dppm)(µ-I)PtMe3(+)·I(-)] (10A, 10B), followed by dissociation of phthalazine and formation of the product complex [Me3Pt(µ-dppm)(µ-I)2PtMe3] (4A, 4B) containing two PtIV centres.. In the other mechanism (Path 1I), oxidative addition occurs at the PtII centre of 7A and 7B, leading also to 10A and 10B. Paths I and II are competitive in acetone, but Path I is preferred in benzene. The first oxidative addition computes as having a lower barrier than the second, in accord with  experiment, and we attribute this to the occurrence of a Pta···Ptb interaction assisting the first oxidative addition at Ptb.