Inorganic Chemistry Research
Volume:4 Issue: 2, Dec 2020

Dimethylplatinum(II) complex [PtMe2(pbt)], 1, with pbt = 2(2pyridyl)benzothiazole ligand, can react with dichloromethane solvent to give the corresponding organoplatinum(IV) complex [Pt(Cl)(CH2Cl)Me2(pbt)]. The reaction gives exclusively trans addition product in which Cl and CH2Cl are located trans to each other. The suggested mechanism for this oxidative addition reaction was computationally investigated and related species during this process are proposed. DFT calculations show that the reaction proceeds through a transition state with the energy barrier of 97.5 kJ/mol. Attempts to grow crystals of the Pt(II) complex 1 in CH2Cl2/nhexane mixture of solvents forms the dichloro Pt(IV) complex [PtCl2Me2(bpt)], which its structure is determined by X-ray crystallography.

The synthesis routes for the preparation of nanostructures have been developed in the past decade. Organometallic precursors played an important role in the synthesis of nanomaterials via various methods of synthesis. In this investigation, nanostructures were synthesized from organometallic precursors and applied as catalyst in various reactions. This mini review is mostly devoted to the research efforts carried out by our group on the search for new classes of organometallic precursors and applying them for the synthesis of nanostructured catalysts with different morphologies. Also we have investigated the effect of alloying and presence of support on catalytic activity. We found that stabilization of nanostructures on graphene oxide, aminoclay, ionic liquids or cyclodextrin supports can increase the catalytic activity by increasing the stability and dispersion. Furthermore, alloyed nanostructures can be efficient like noble metal catalysts in catalytic applications. Also, thin films fabricated by this method showed higher quality in comparison with the thin films fabricated by other synthetic methods.

Hydrous zirconia nanoparticles were covalently functionalized by 3-(trimethoxysilyl)-propylchloride and ethylenediamine to support VO(acac)2 complex. The prepared catalyst has been characterized by means of FT-IR spectroscopy, PXRD pattern, thermal analysis, elemental analysis, and scanning electron microscopy. Then it was used for the epoxidation of cis-cyclooctene. The catalytic procedure was subsequently investigated for each catalyst and followed by Gas-Liquid Chromatography. It was also applied repeatedly in the optimum reaction conditions to reveal its recycling ability. Then these conditions were used for successful epoxidation of other linear and non-linear alkenes.

Catalytic activity of a Pd/biphenyl based- phosphine system in the Ullmann cross-coupling reaction of various para-substituted aryl bromides were investigated. The results showed that the bulky electron-rich phosphine efficiently modify the electronic and steric properties of palladium center and promote the cross-coupling reaction. Mechanistic study using the Hammett correlation revels that electron-withdrawing substituents decrease the electron density at the palladium center and decrease the rate of oxidative-addition step such that this step will become the rate determining step (rds). On the other hand, electron-donating groups increase the rate of oxidative-addition step such that the reductive-elimination step will become the rds.

Boehmite nanoparticles were covalently functionalized by 3-(trimethoxysilyl)-propylamine to support H5[PMo10V2O40] and H5[PW10V2O40] Keggin type heteropolyacids. After characterizing these catalysts by FT-IR, PXRD, TG/DTA, CHN, ICP, and TEM techniques, they were applied to the epoxidation of cis-cyclooctene. The progress of the reactions was investigated by gas-liquid chromatography and the catalytic procedures were optimized for the parameters involved, such as the solvent and oxidant. The results showed that 20 mg of supported H5[PMo10V2O40] catalyst in 2 ml C2H4Cl2 with 0.5 mmol cyclooctene and 1 mmol tert-butyl hydroperoxide at reflux temperature gave 98% yield over 60 minutes. Recycling experiments revealed that these nanocatalysts could be repeatedly applied up to four times for a nearly complete epoxidation of cis-cyclooctene. The optimized experimental conditions were also used successfully for the epoxidation of some other alkenes such as cyclohexene, styrene and α-methyl styrene.

Development of highly efficient and fast-rate adsorbents has recently attracted intense attention of researchers for wastewater treatment. However, only few investigations have been done on the selective and fast-rate removal of Congo red and methyl orange by coordination polymers. In this work, a new cobalt-based coordination polymer was constructed via simple precipitation method by addition of diethyl ether to the methanolic solution of glutaric acid and cobalt acetate. Two anionic (Congo red and methyl orange) and two cationic (methylene blue and Rhodamine B) dyes were chosen as model targets to examine the adsorption efficiency of the prepared Co-ICP. The experimental data indicated that unlike the cationic dyes, the anionic dyes are excellent targets for adsorption by Co-ICP probably due to stronger electrostatic interactions. Furthermore, it was found that, only after 2 minutes the removal efficiency of Congo red by Co-ICP reaches to 88%. The analytical data confirmed the preservation of the primary structure of the Co-ICP even after 24 h soxhlet washing. The efficiency of obtained Co-ICP for anionic dyes removal partly decreased after four cycles probably due to the occupation of some adsorption sites and reduction of adsorption capacity.

Cycloplatinated(II) complexes are an important class of organoplatinum(II) compounds with impressive photophysical properties. The luminescent cycloplatinated(II) complexes have been employed in many aspects such as optoelectronic devices and bio-imaging applications. The center of emission in these complexes is significantly attributed to the cyclometalated ligand. The emission properties of this chromophoric ligand is perturbed by Pt(II) center as a heavy metal ion and also can be controlled by other ancillary ligands. The role of ancillary ligand seems to be crucial in tuning the photophysical properties of such complexes. In addition to the normal emissions that arise from the cyclometalated ligand, the ancillary ligand(s) may induce some emissions which are created by intra- or inter-molecular Pt…Pt and π…π interactions. In this regard, the presence of the other metal centers like Ag(I), Au(I), Tl(I) and Pb(II) in the structures of cycloplatinated(II) complexes may considerably affect their emission properties. Since almost 10 years ago, we have started to employ different kinds of ancillary ligands toward different cycloplatinated(II) precursor complexes and study their influences on the structural and photophysical properties of these complexes. In this direction, the new complexes were predominantly identified by means of NMR and Mass spectroscopies together with X-ray crystallography. For photophysical investigations, the UV-Vis and photoluminescence spectroscopies were applied and the obtained results were rationalized with the help of DFT calculation method. In this review article, we tried to share our experiences in this attractive field of research and mention how some of these luminescent complexes synthesized during these years.

In the present study, the goal was the synthesis, characterization, surface morphology and thermal ‎properties of organic-inorganic hybrid material of polyaniline/Ca-Fe layered double hydroxide ‎nanocomposites (Ca/Fe-LDH /PANI NCs). At first, Ca/Fe-LDH with intercalate bio-safe tartrate ‎anion (TA-Ca/Fe-LDH) was prepared via the co-precipitation and hydrothermal method. The ‎surface of as-synthesized TA-Ca/Fe/LDH was successfully modified by 3-‎aminopropyltriethoxysilane coupling agents. Then, polymer matrix nanocomposites (PMNCs) were ‎fabricated by in situ polymerization of aniline in the presence of different amounts of modified LDH. ‎The as-prepared PMNCs were characterized by X-ray diffraction, Fourier transform infrared, ‎transmission electron microscopy, field emission scanning electron microscopy, and ‎thermogravimetric analysis (TGA) techniques. The results of morphological studies showed the ‎morphological structure similar to the lamellar ‎structure and plate-like shape particles. According to ‎the TEM results, the sizes of the particle were reduced less than 33 nm. According to TGA results, ‎the thermal stability of polyaninline wad improved by adding modified LDH‎. ‎Also by increasing ‎silane modified LDH contents in the final NCs, the char yields at 700 °C were ‎improved.‎

An aminopropyl-functionalized multi-walled carbon nanotubes (NH2-MWCNTs) was used as a suitable modified solid nanomaterial to immobilize efficient epoxidation active catalyst like Venturello anion i.e. {PO4[W(O)(O2)2]4}3−, via strong electrostatic interaction. FT-IR spectroscopy, CHN analysis, energy dispersive X-ray (EDX) spectroscopy, N2 adsorption-desorption technique, and transmittance electron microscopy (TEM) confirmed the successful immobilization of Venturello anion and synthesis of desired heterogeneous catalyst. Superior catalytic activity was achieved in the epoxidation of some olefins (e.g. > 99 % for cyclooctene and > 86% for cyclohexene) in the presence of prepared heterogeneous catalyst with utilizing H2O2 as green and benign oxidant. Moreover, the high stability and reusability of catalyst was examined in 4th catalytic cycles which approves its stability without loss of its activity.

Two new mercury(II) Schiff base complexes [Hg((2,6-Cl-ba)2-1,2-pn)X2] (X = Cl (1), I (2) and (2,6-Cl-ba)2-1,2-pn = N,N'-bis(2,6-dichlorobenzylidene)-1,2-diaminopropane) have been synthesized and characterized by elemental analysis (CHN), FT-IR and 1H-NMR spectroscopy. The crystal structure of complexes 1 and 2 were determined by single-crystal X-ray diffraction. X-ray results shown that the mercury(II) ions in these complexes have a distorted tetrahedral geometry with HgN2Cl2 and HgN2I2 chromophores, respectively. In these complexes, the Schiff base ligand (2,6-Cl-ba)2-1,2-pn act as chelating bidentate ligand, coordinating via the two iminic nitrogen atoms and it adopts an E,E conformation. Finally, the thermal behavior of complexes was study using thermogravimetry in order to evaluate their thermal stability and thermal decomposition pathway.

In this study, a new N3-Schiff base ligand (L) was obtained from via condensation reaction of diethylenetriamine and (Z)-3-(4-(dimethylamino)phenyl)acrylaldehyde (1:2 ratio). Then some its new five coordinated HgLX2 complexes inwhich X is halide/pseudohalide were synthesized. The ligand and its complexes were characterized by various analysis tools such as FT-IR, 1H and 13C NMR, UV–visible, thermal analyses and molar conductivity measurements. Based on the spectral data and conductivity measurements, all the newly prepared compounds were found to be non-electrolyte. Moreover some mercury complexes were prepared in nano-structured size by sonochemical method and confirmed by X-ray powder diffraction method (XRD) and scanning electron microscopy (SEM) analyses. The Schiff base and its mercury complexes have been screened for their in-vitro antibacterial activities (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis) and antifungal activities (Candida albicans and Aspergillus oryzae) using well diffusion method. Furthermore, thermal behaviors of ligand and its mercury complexes were evaluated in the range of room temperature to 1000°C under nitrogen atmosphere. The Schiff base ligand and complexes were decomposed completely via 2 to 5 thermal steps.

In previous studies, the mechanism for the reduction of Tetrachrorido platinum(IV) complex with 5ˊ-dGMP has been investigated. In this research, two platinum(IV) complexes [PtCl4(N-N)] (N-N = 4,4ˊ-dimethyl -2,2ˊ-bipyridine, A and 5,5ˊ-dimethyl -2,2ˊ-bipyridine, B) were considered and compared with PtIVdach (N-N = diamino cyclohexane) theoretically, by means of the Becke3LYP DFT functional calculations. The mechanism of two electron reduction were thoroughly followed for three compounds. The relatives Gibbs energies for all intermediate, transition states and products were calculated and compared. LUMO –HOMO energy gap was also determined, where this energy gap was 3.5ev in complexes A and B; and 4.5ev in PtIVdach. The overall calculated Gibbs energy for the formation of corresponding PtII complex is 30.0 kJ/mol in A, 28.5 kJ/mol in B and 43.2 kJ/mol in PtIVdach. Thus compounds A and B illustrate more favorability for the proposed two electron reduction, interestingly. The results demanded that the hydrogen bonds play a critical role in the stability of intermediates and transition states in PtIVdach. The effective parameters in the mechanism were also discussed.