Pd Metal Complexes Research Articles

Synthesis of novel NHC-based transition metal complexes of Pd(II), Au(I), Cu(I) and Ir(III) with pendant 1,2,3-triazole group for remediation of rhodamine B

The transition metal-NHC complexes presented here were all created by us. For instance, A bidentate ligand, [L1-H(Br)] having 1-methyl imidazolium salt, using for N-heterocyclic carbene as precursor, connected to a pendant triazole moiety via methylene bridge has been synthesized via ‘CuAAC’ or ‘Click’ reaction. Imidazolium salt, [L1-H(PF6)] with a non-coordinating anion PF6 has been prepared via anion exchange of [L1-H(Br)] with NH4PF6. Reaction of [L1-H(PF6)] with half an equivalent of Ag2O yielded the Ag(I)–NHC complex [(L1)2Ag](PF6). This Ag(I)–NHC complex is shown to be an excellent carbene transfer agent to other transition metals, both linear and non-linear, when reacted with appropriate equivalents of metal precursors to give variety of organometallic metal-NHC complexes via transmetallation. The compound [(L1)IrCl(Cp*)](PF6) has been applied for the remediation of a water pollutant rhodamine B dye from wastewater. The results of this study also provide good opportunities for organic synthesis in future research.

Preparation, characterization of some transition metal complexes of hydrazone derivatives and their antibacterial and antioxidant activities

A new series of metal complexes of Pd(II), Cd(II) and Cu(II, I) of polydentate Schiff base ligand (H2L), namely ((Z)-2-(phenylamino)-N'-(thiophen-2-ylmethylene) acetohydrazide) have been prepared. The ligand and its metal complexes have been characterized based on various physicochemical studies as elemental analyses, molar conductance, spectral (UV–Vis, MS, IR, 1H NMR, 13C NMR and XRD), magnetic moment measurements and thermal studies (TG, DTG). In the view of previous studies, the ligand (H2L) acts as polydentate one and coordinates with metal ions to form all metal complexes. The kinetic and thermodynamic parameters of decomposition process (ΔG, ΔH, ΔS) were calculated. The possible structures of the metal complexes have been computed using the molecular mechanic calculations using the hyper chem. 8.03 molecular modeling program. The calculations are performed to obtain the optimized molecular geometry. The antibacterial study of the selected compounds was assayed against two pathogenic bacteria. Moreover, the complexes (Cu II, I), Cd(II), Pd(II)) and the ligand revealed excellent antioxidant properties and could be useful in fighting the free radicals which occur in close connection with cancerous cells. It was remarkable that the two complexes (Cu II, I) demonstrated stronger antioxidant effects than their parent compounds. It is clear that the new complexes are good active compounds for use in a variety of applications.

Electronic structure and adsorption geometry of Pt and Pd metal complexes with 1,3-dithiole-2-thione-4,5-dithiolate ligand on TiO2(101) surface from first-principles calculations

Metal complexes based on 1,3-dithiole-2-thione-4,5-dithiolate (dmit) ligand have been intensively studied for more than 40 years due to their unusual chemical and physical properties. Besides, the highly delocalized frontier orbitals, that allow direct electron transfer through the ligand π orbitals, make these class of complexes promising candidates for photochemical devices as well as sensitizer for dye-sensitized solar cells. In this work, we investigated the electronic and geometric properties of Pd and Pt (CH3)2[M(dmit)2] complexes isolated on TiO2(101) surface by means of first-principles calculations using plane-wave basis sets and DFT calculation. Adsorption energies of metal complexes supported on a TiO2(101) surface are calculated for three different configurations, linked by the sulfur atom of Sthione, Sthiole–Sthiolate, and planar. The studies found that the most stable adsorption molecular configuration mode for the palladium(II) and platinum(II) complexes is the planar mode. TD-DFT molecular calculations revealed that the lowest energy transition in the ultraviolet visible near-infrared range mainly corresponds to the HOMO–LUMO excitation for the (CH3)2[M(dmit)2] complexes. Theoretical calculations of optical absorption spectra of (CH3)2[M(dmit)2] complexes adsorbed on the anatase (101) surface show that the interaction induces a slightly redshift of electronic absorption bands. Density of states for the metal complexes/TiO2(101) system revealed that the LUMO of the metal complexes lies at below the edge of the TiO2 conduction band. The adsorption of the (CH3)2[Pd(dmit)2] complex on the anatase (101) surface results in the emergence of new transitions below 1 eV that can be ascribed to the presence of a favorable overlap between the LUMO of the complex and the conduction band of the TiO2 semiconductor.

New α‐(N)‐Heterocyclic Thiosemicarbazones Compounds Including The Cu2+ And Pd2+ Complexes: Applications Towards Potential Anti‐Cancer Agents

Our research team has synthesized new compounds involving the reaction of α‐(N)‐heterocyclic substrates, including methyl‐imidazole‐2‐carboxaldehyde, with several commercially available thiosemicarbazides (TSC's) to form many new α‐(N)‐heterocyclic thiosemicarbazone compounds, which act as tridentate monoanionic ligands with Cu2+ and Pd2+. These ligands were synthesized in the lab, recrystallized, and analyzed via ¹H NMR and ¹³C NMR spectroscopy using ¹H detected ¹³C and 15N Heteronuclear Single Quantum Coherence (HSQC) and Heteronuclear Multiple‐Bond Correlation (HMBC) experiments. The NMR spectra show evidence for the proposed structures for the ligands. We have performed anti‐proliferative MIC (minimum inhibitory concentration) studies using seven different microbes with the ligands and the metal complexes in order to determine the anti‐microbial properties of each TSC compound synthesized, and have found that the Cu and Pd metal complexes of these ligands have significant anti‐proliferative activities. We relate these anti‐microbial properties to activity against Topoisomerase IIa.

Hydrogen generation from hydrolysis of sodium borohydride with a novel palladium metal complex catalyst

Generally, the complex catalyst is considered homogeneous catalyst, which is coordinated some ligands. In this study, we have treated a solid–state complex catalyst for NaBH4 hydrolysis. We report the synthesis of salicylaldimine ligand and its Pd metal complex. The obtained Pd catalyst is tested for hydrogen generation from the hydrolysis of NaBH4. The effects of temperature, NaBH4 concentration, NaOH concentration and catalyst amount on the catalytic activity toward hydrogen production from hydrolysis of NaBH4 are comparatively investigated. The Pd-containing catalyst is characterized by various techniques, including X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Fourier transform infrared spectroscopy (FTIR).

Studies on thermogravimetric analysis and solvophobic interactions of micellization of Pd (II) complex in non aqueous solvents

The present paper deals with the synthesis and characterization of a Pd (II) metal complex by means of various spectroscopic, thermogravimetric and physicochemical techniques. The Pd metal complex was found to be thermally stable with melting point at 193°C. Thermodynamic decomposition parameters and activation energy were obtained using various methods. The micellization behavior of the complex was examined in different alcohols (n=2–5) and at various temperatures. Self assembly of synthesized metallosurfactant resulted in formation of inverted metallomicelles with cmc in range of 0.7–0.8mM. Thermodynamically micellization process was found to be enthalpy driven. Dynamic redox electrochemical behavior changes from reversible to irreversible process with change of alcohol as solvent for different micellar solution. The size of Pd ‘inverse’ metallomicelles was found to increase with increase in the hydrophobicity of the solvent. Moreover, the study also takes into account the role of metal ion in modifying the properties of a metallosurfactant.

Synthesis, Structural, and Antibacterial Studies of Some Transition Metal Complexes Derived from Thiosemicarbazone and Semicarbazone

A series of metal complexes of Pd(II), Pt(II), Rh(III), Ir(III), and Ru(III) with thiosemicarbazone and semicarbazone of 2-acetyl thiophene have been synthesized. Their structures were determined on the basis of elemental analyses; molar conductance; magnetic susceptibility measurements; and IR, 1 H NMR, and electronic spectral studies. On the basis of molar conductance, the complexes may be formulated as [M(L)2]Cl2 and [M′(L)2Cl2]Cl [where M = Pd(II), Pt(II) and M′ = Rh(III), Ir(III), and Ru(III)] due to their 1:2 and 1:1 electrolytic nature. On the basis of IR, 1H NMR, and electronic spectral studies, an octahedral geometry has been assigned for Rh(III), Ir(III), and Ru(III), while square planar geometry has been assigned for the Pd(II) and Pt(II) complexes. The synthesized ligands and their complexes have been screened for bactericidal activity against several bacterial species (i.e., B. macerans, A. aureus, E. coli), and it is shown that the metal complexes act as more active antimicrobial agents than the uncomplexed ligands from which they derive.

Electrochemical formation and properties of two-component films of transition metal complexes and C60 or C70

The electrochemically active polymers have been formed during electro-reduction carried out in solution containing fullerenes, C60 or C70, and transition metal complexes of Pd(II), Pt(II), Rh(III), and Ir(I). In these films, fullerene moieties are covalently bounded to transition metal atoms (Pd and Pt) or their complexes (Rh and Ir) to form a polymeric network. All films exhibit electrochemical activity at negative potentials due to the fullerene cages reduction process. For all studied metal complexes, yields of formation of films containing C70 are higher than yields of electrodeposition of their C60 analogs. C70/M films also exhibit higher porosity in comparison to C60/M layers. The differences in film morphology and efficiency of polymer formation are responsible for differences in electrochemical responses of these films in acetonitrile containing supporting electrolyte only. C70/M films shows more reversible voltammeric behavior in negative potential range. They also show higher potential range of electrochemical stability. Processes of film formation and electrochemical properties of polymers depend on the transition metal ions or atoms bonding fullerene cages into polymeric network. The highest efficiency of polymerization was observed for fullerene/Pd and fullerene/Rh films. In the case of fullerene/Pd films, the charge transfer processes related to the fullerene moieties reduction in negative potential range exhibit the best reversibility among all of the studied systems. Capacitance performances of C60/Pd and C70/Pd films deposited on the porous Au/quartz electrode were also compared. Capacitance properties of both films are significantly affected by the conditions of electropolymerization. Only a fraction of the film having a direct contact with solution contributes to pseudocapacitance. Capacitance properties of these films also depend on the size of cations of supporting electrolyte. The C70/Pd film exhibits much better capacitance performance comparison to C60/Pd polymer.

Solvent-free isomerization of methyl chavicol to trans-anethole using transition metal complexes as catalysts

Metal complexes of Pd, Ru and Rh were studied for the isomerization of methyl chavicol 1-methoxy-4-(2-propen-1-yl)benzene to trans-anethole (1-methoxy-4-(1-propen-1-yl)benzene) at 491 K and atmospheric pressure without using any solvent. The complex RuCl 3(AsPh 3) 2 · CH 3OH showed the highest conversion (97%) with selectivity (87%) for trans-anethole.

Reaction chemistry of palladium acetate complexes in polycarbonate: a comparative study

Palladium acetate complexes have been incorporated into polycarbonate (PC) films as a dispersion medium using tetrahydrofuran (THF). The resulting light brown-coloured homogeneous films of 10–30 wt.% Pd metal complex concentration are found to be thermally stable up to 150°C, and the relatively electron rich oxygen atoms of ketone groups in polycarbonate molecules are assumed to interact with Pd complexes on the basis of their infrared spectroscopic and thermal analyses. The reaction chemistry of Pd in PC has been investigated by reacting Pd sites with small gaseous molecules such as CO, H 2, O 2, NO, and olefins in the temperature range of 25 to 150°C, and various Pd-carbonyls, -hydride, -nitrosyl, and -ethylene species formed in PC are characterized. The treatment of Pd-containing PC film with H 2 gas at 120°C produces small Pd metal particles of ca. 40–330 Å in diameter in PC, which show various catalytic reactivities in CO oxidation, NO reduction, dimethyl carbonate formation and hydrogenation of styrene-monomer.

Pd(II)-catalyzed addition polymerization and ring opening metathesis polymerization of alicyclic monomers: routes to new matrix resins for 193 nm photolithography

A series of alicyclic polymers designed for 193 nm photoresist applications have been synthesized and characterized. These polymers were synthesized by Pd(II)-catalyzed addition and ring opening metathesis polymerization techniques. Methods for removing residual metal complexes of Pd(II) and Ir(IV) from alicyclic polymers were developed. The low absorbance of these polymers at 193 nm and their high dry etch resistance make them attractive candidates for 193 nm lithography. When formulated with onium-type photoacid generators and plasticizers in propylene glycol monomethyl ether acetate, these photoresists have demonstrated high resolution and high sensitivity.

5690747 Method for removing photoresist with solvent and ultrasonic agitation

A series of alicyclic polymers designed for 193 nm photoresist applications have been synthesized and characterized. These polymers were synthesized by Pd(II)-catalyzed addition and ring opening metathesis polymerization techniques. Methods for removing residual metal complexes of Pd(II) and Ir(IV) from alicyclic polymers were developed. The low absorbance of these polymers at 193 nm and their high dry etch resistance make them attractive candidates for 193 nm lithography. When formulated with onium-type photoacid generators and plasticizers in propylene glycol monomethyl ether acetate, these photoresists have demonstrated high resolution and high sensitivity.

5691117 Method for stripping photoresist employing a hot hydrogen atmosphere

A series of alicyclic polymers designed for 193 nm photoresist applications have been synthesized and characterized. These polymers were synthesized by Pd(II)-catalyzed addition and ring opening metathesis polymerization techniques. Methods for removing residual metal complexes of Pd(II) and Ir(IV) from alicyclic polymers were developed. The low absorbance of these polymers at 193 nm and their high dry etch resistance make them attractive candidates for 193 nm lithography. When formulated with onium-type photoacid generators and plasticizers in propylene glycol monomethyl ether acetate, these photoresists have demonstrated high resolution and high sensitivity.

Metal complexes of new chiral tridentate ligands with N, P and S donors: The crystal structure of [( S)-Ph 2POCH 2CH(NMe 2)CH 2CH 2SCH 3]W(CO) 3

Two new ligands, ( S)-Ph 2POCH 2CH(NMe 2)CH 2CH 2SCH 3, derived from L-methionine, and ( R)-Ph 2POCH 2CH(NMe 2)CH 2-SCH 3 from L-cysteine have been prepared and characterized. Several metal complexes of Pd, Mo and W have been prepared. These ligands produce a chiral electronically asymmetric environment at the metal that is evidenced by trans influences on the other ligands. A crystal structure has been determined for [( S)-Ph 2POCH 2CH(NMe 2)CH 2CH 2SCH 3]W(CO) 3. The sulfur adopts an S s configuration in the solid and significant trans influences are observed in the metrical parameters of the carbonyls. This tungsten complex crystallizes in the monoclinic space group P2 1 with a = 8.8435(6) Å, b = 14.384(1) Å, c = 9.546(1) Å, β = 107.01(8), Z = 2 and V = 1161.0(4) Å 3.

Development of Organic Polymer-bound Metal Complex Catalysts.

Preparation of polystyrene and ethylene oligomer-bound transition metal complexes (metal: Pd, Rh, Ni, Ru and Nd) and their catalysis for various organic reactions have been studied. Heterogeneous phosphinated polystyrene-bound Pd(II) complexes prepared by the reaction of phosphinated polystyrene with PdCl2, which could be used for reusable catalysts for selective hydrogenation of olefins and acetylenes, and for codimerization of acetylenes and allylic halides. Cationic Pd(II) complexes obtained from the treatment of the polymeric Pd(II) complexes with AgBF4 had the catalytic activity for selective cooligomerizations of olefins. Reduction of the polymeric Pd(II) complexes with hydrazine gave polymer-bound Pd(0) complexes as stable species, which had catalytic activities for representative types of Pd(0)-induced organic reactions. Aminated polystyrene-bound Rh carbonyl cluster complexes (Rh6, Rh7, and Rh14 species) were selectively formed by the reaction of aminated polystyrenes with Rh6(CO)16 in the presence of H2O and CO. These polystyrene-bound Rh cluster anion complexes catalyzed deoxygenation of various N-O bonds (nitro compounds, oximes, hydroxyl amines, and N-oxides), hydrohydoxymethylation of olefins, and selective reduction of carbonyl compounds under the WGSR conditions. Amino moieties on polystyrene play an important role, both in the generation of active Rh species and the catalysis for the above reactions.Functional linear ethylene oligomers (degrees of polymerization between 150-300) having phosphine, phosphinite, and carboxylate ligands were synthesized. The treatment of the functional oligomers with transition metal complexes of Pd, Rh, Ru, Ni, and Nd gave the corresponding oligomer-bound metal complexes, which were recoverable and reusable homogeneous catalysts for a wide variety of organic reactions (hydrogenation, oligomerization, allylic substitution, oxidation, etc.). Such oligomeric complexes dissolved completely in the above reaction conditions at 100-110°C and cooling the solutions led to quantitative recovery of heterogeneous catalysts. Their reactivity and selectivity in the above reactions accurately mirror those of low molecular weight analogs. A combination catalyst system of ethyleneoligomer-bound Rh(I) complex and polyvinylpyridine-bound Cr(VI) complex could be used for the two-step oxidation reduction sequence (wolf and Lamb reaction); unsaturated alcohols gave directly saturated ketone in a H2 atmosphere.

Some analytical applications of aromatic sulfonyl haloamines: Determination of thiosemicarbazide alone and in its metal complexes with bromamine-B and dichloramine-B

Simple, rapid, and reproducible back titration methods for the determination of thiosemicarbazide (TSC) in free state and in Zn, Cd, Hg, Ni, Pt, and Pd metal complexes with bromamine-B (BAB) and dichloramine-B (DCB) have been developed. The oxidation reaction involves a 12-electron change per TSC molecule in 0.2–1.0 M NaOH and water-acetic acid media with BAB and DCB, respectively. The proposed analytical procedures for the assay of TSC are also useful for computing the number of TSC ligands present in the respective metal complexes. The two aromatic sulfonyl haloamines used, BAB and DCB, were prepared and then characterized by 13C FT-NMR spectral data.

Some analytical applications of aromatic sulfonyl haloamines: Determination of thiocyanate and cyanide ions in metal complexes and salts and thiosemicarbazide in metal complexes with bromamine-T

A simple, rapid, and accurate method for the determination of thiocyanate and cyanide ions in metal complexes and salts, and thiosemicarbazide (TSC) in Zn, Cd, Hg, Ni, Pt, and Pd metal complexes with excess of bromamine-T has been developed. The oxidation involves eight- and two-electron changes, respectively, with NCS− and CN− ions and a 12-electron stoichiometry per TSC molecule, in 0.1–0.2 N NaOH medium. The proposed method could be employed for computing the number of thiocyanate, cyanide, and TSC ligands in the respective complexes. The aromatic sulfonyl haloamine, bromamine-T, has been prepared and characterized by uv, ir, and FT NMR 1H and 13C spectral data and its mass spectrum.