PdCl2 Complexes Research Articles

Development and Application of SPOSiPs: A Class of Diphosphine Ligands Based on SPOSiOL.

Here, we report the development and application of a novel class of spirosilacycle-based diphosphine ligands (SPOSiPs). This type of diphosphine ligand could be readily prepared in two steps with high efficiency starting from enantiopure spirobiphenoxasilin-diol (SPOSiOL). According to the structural analysis of SPOSiP and its PdCl2 complex, SPOSiPs possess a flexible chiral pocket and feature a rigid configuration, a large dihedral angle, a long P-P distance, and a large P-M-P bite angle in their metal complexes. The potentials of SPOSiPs in asymmetric catalysis have also been preliminarily disclosed.

Crystal structure and Hirshfeld surface analysis of di-chlorido-[2-(3-cyclo-pentyl-1,2,4-triazol-5-yl-κN 4)pyridine-κN]palladium(II) di-methyl-formamide monosolvate.

This study presents the synthesis, characterization and Hirshfeld surface analysis of the title mononuclear complex, [PdCl2(C12H14N4)]·C3H7NO. The compound crystalizes in the P21/c space group of the monoclinic system. The asymmetric unit contains one neutral complex Pd(HL c-Pe)Cl2 [HL c-Pe is 2-(3-cyclo-pentyl-1,2,4-triazol-5-yl)pyridine] and one mol-ecule of DMF as a solvate. The Pd atom has a square-planar coordination. In the crystal, mol-ecules are linked by inter-molecular N-H⋯O and C-H⋯N hydrogen bonds, forming layers parallel to the bc plane. A Hirshfeld surface analysis showed that the H⋯H contacts dominate the crystal packing with a contribution of 41.4%. The contribution of the N⋯H/H⋯N and H⋯O/O⋯H inter-actions is somewhat smaller, amounting to 12.4% and 5%, respectively.

Well-defined (NHC)PdCl2(azetidine) complexes: Synthesis, characterization and catalytic activities

The synthesis of a series of well-defined (N-heterocyclic carbene)PdCl2(azetidine) complexes are presented. The structures of all complexes were fully characterized by 1H-NMR and 13C-NMR, which supported the proposed structures. The molecular structures of all complexes were further determined by single-crystal X-ray diffraction. The catalytic activities of the obtained Pd-complexes were then evaluated in Suzuki-Miyaura, Sonogashira and Mizoroki-Heck coupling reactions.

Molecular studies regarding colon cancer cell line (HCT116) treated by new ruthenium and palladium complexes

Ru(H2dtpa) (H2O) and Pd (DME)Cl2 were prepared, and their structures were confirmed by different structural tools. [Ru(H4dtpa) (cysteine)] Cl was separated as a model for the interaction of Ru (III) complex containing DTPA ligand with its corresponding most active amino acid and the geometrical parameters for the ternary complex and their constituent ligands are evaluated. Cytotoxicity was examined for both complexes against different cancer cell lines (HCT116, A549 and Mcf7). They were tested against a normal human lung cell line (W138). In addition, both complexes ensured cytocidal, not cytostatic effect. Several molecular tools were utilized in order to figure out the mechanism of action that two complexes followed to inhibit human colon cancer (HCT116) cell line. Gene expression analysis, cell cycle assay, genomic DNA analysis, and apoptosis were a molecular techniques that proved both Ru(H2dtpa) (H2O) and Pd (DME)Cl2 complexes were promising and effective chemotherapeutic agents against colon carcinoma in this current study. So, authors recommended more in vivo future studies should be done to make sure of complexes bioactivity and safety before they would be used commercially.

The C-3 Functionalization of 1H-Indazole through Suzuki–Miyaura Cross-Coupling Catalyzed by a Ferrocene-Based Divalent Palladium Complex Immobilized over Ionic Liquid, as Well as Theoretical Insights into the Reaction Mechanism

The C-3 functionalization of 1H-indazole could produce a lot of highly valuable pharmaceutical precursors, which could be used for the treatment of cancer and many other inflammatory diseases. This work was focused on the C-3 functionalization of 1H-indazole through Suzuki–Miyaura cross-coupling of 3-iodo-1H-indazole with organoboronic acids, catalyzed by various palladium catalysts immobilized over imidazolium ionic liquids, as well as catalyst recycling. A series of reaction parameters, including the substrate, catalyst, and ionic liquid, were fully investigated. It is significant to note that the yields of the present Suzuki–Miyaura cross-coupling were mainly determined by the catalyst and the solvent used, more than the chemical structure of the substrate. Furthermore, ferrocene-based divalent palladium complexes showed better catalytic outputs compared to simple palladium salts. Moreover, using two imidazolium ionic liquids, BMImX (BMIm+ = 1-n-butyl-3-methylimidazolium, X− = BF4−, PF6−) not only improved the yields of cross-coupled products, but also avoided the formation of Pd(0) black, as compared to the non-ionic liquid facilitated reactions, and simultaneously making catalyst recycling more effective. On average, BMImBF4 performed better than BMImPF6. Additionally, scientific calculations revealed that 1,1′-bis(diphenylphosphino)ferrocene-palladium(II)dichloride dichloromethane complex (PdCl2(dppf)) showed a lower energy barrier in the formation of intermediates than [1,1′-bis(di-tert-butylphosphino)ferrocene]dichloropalladium(II) (PdCl2(dtbpf)), leading to higher catalytic outputs. This work may contribute to the development of 1H-indazole-derived new pharmaceuticals.

Rhenium(V) Tris(pyrazolyl)borate Complexes as Ligands in Square Planar Palladium and Platinum Complexes

The reactions of TpReO(SnC3H7)2 (Tp = tris(pyrazolyl)borate anion) with acetonitrile complexes PdCl2(MeCN)2 and PtI2(MeCN)2 in toluene solutions resulted in the formation of new heterometallic rhenium complexes TpReO(µ-SnC3H7)2MX2 (MX2 = PdCl2 (I), MX2 = PtI2 (II)). A similar complex TpReO(µ-SnC3H7)2PdI2 (III) was formed either on treatment of I with NaI in dichloromethane or in the reaction of TpReO(SnC3H7)2 with a suspension of PdI2 in toluene. Complexes I–III were characterized by IR and NMR spectroscopy and by X-ray diffraction (CCDC nos. 2172225–2172227).

Preparation, Characterization and Antimicrobial Activity of Pd(II), Zn(II) and Cu(II) Complexes of Benzimidazoles and Schiff Bases Including Ferrocene Group

PdCl2, ZnCl2 and CuCl2 complexes of three benzimidazole derivatives and two Schiff bases having the ferrocene group were synthesized and characterized. It was unexpectedly noticed that the Pd(II) and Zn(II) complexes exhibit paramagnetic characters corresponding to about one electron caused by the ferrocene moiety. For the same reason, the magnetic moment value of the Cu(II) complexes was also higher than the anticipated values. Besides, the antimicrobial activity of the complexes was investigated against six bacteria and three fungi. Comparing the ligands, the Schiff bases exhibited higher antimicrobial activity than the benzimidazole derivatives, especially on Gram+ bacteria. Among all compounds investigated in this work, [Zn(SB1)2]·2H2O showed the highest activity against S. epidermidis and S. aureus which are Gram+ bacteria.

Synthesis and Characterization of Phosphinecarboxamide and Phosphinecarbothioamide, and Their Complexation with Palladium(II) Complex

Reactions of isocyanates/isothiocyanates with primary and secondary phosphines without solvent at room temperature afforded phosphinecarboxamide/phosphinecarbothioamide, respectively, in excellent yields. Furthermore, palladium complex Pd(COD)Cl2 was allowed to react with Ph2PC(O)NHPh (1a) to afford [Pd{Ph2PC(O)NHPh-κP}2Cl2] (3). On the other hand, the reaction of Pd(COD)Cl2 with 1 eq. of Ph2PC(S)NHPh (2a) afforded [PdCl2{Ph2PC(S)NHPh-κP,S}] (4). In the case of a 1:2 molar ratio, [PdCl{Ph2PC(S)NHPh-κP,S}{Ph2PC(S)NHPh-κP}]Cl (5) was formed. The newly obtained compounds were fully characterized using multielement NMR measurements and elemental analyses. In addition, the molecular structures of Ph2PC(O)NH(CH2)2Cl (1j), Ph2PC(S)NHPh(4-Cl) (2c), and 3–5 were determined using single-crystal X-ray diffraction.

Carbonylative Suzuki Coupling Catalyzed by Pd Complexes Based on [N,P]‐Pyrrole Ligands: Direct Access to 2‐Hydroxybenzophenones

AbstractThe Suzuki‐Miyaura cross‐coupling is one of the most useful synthetic tools to build C−C bonds, but the use of hydroxyaryl halides to direct access hydroxy‐byaryls still remains a challenge. For the carbonylative version of the reaction, the synthesis of hydroxybiaryl ketones is commonly solved by protecting group strategies. In this work, we report a protocol of carbonylative Suzuki‐ Miyaura coupling catalysed by a [N,P]‐PdCl2complex using aryl halides, various aryl boronic acids and CO. We were able at first to obtain biphenyls, finding a singular reactivity towards 2‐bromophenol, that later was extended to the carbonylation reaction, resulting in methodology that allows the obtention of 2‐hydroxybiaryl ketones, with a functional group tolerance toward amines, alkoxy, ketones, esters, and halides.magnified image

Synthesis, Characterization, Thermal Analysis, DFT, and Cytotoxicity of Palladium Complexes with Nitrogen-Donor Ligands.

Three new palladium complexes ([Pd(DABA)Cl2], [Pd(CPDA)Cl2], and [Pd(HZPY)Cl2]) bearing dinitrogen ligands (DABA: 3,4-diaminobenzoic acid; CPDA: 4-chloro–o-phenylenediamine; HZPY: 2-hydraziniopyridine) were synthesized, characterized, and tested against breast cancer (MCF-7), prostate carcinoma cell line (PC3) and liver carcinoma cell line (HEPG2). [Pd(DABA)Cl2] complex exhibited the highest inhibition percentage, lying between 68–71%. The hydrolysis mechanism of each palladium complex, the key step preceding the binding to the biological target, as well as their photophysical properties were explored by means of DFT and TDDFT computations. Results indicate a faster hydrolysis process for the Pd(DABA)Cl2 complex. The computed activation energies for the first and second hydrolysis processes suggest that all the compounds could reach DNA in their monohydrated form.

Formation of exceptional monomeric YPhos-PdCl2 complexes with high activities in coupling reactions.

The use of well-defined palladium(ii) complexes as precatalysts for C-X cross-coupling reactions has improved the use of palladium catalysts in organic synthesis including large-scale processes. Whereas sophisticated Pd(ii) precursors have been developed in the past years to facilitate catalyst activation as well as the handling of systems with more advanced monophosphine ligands, we herein report that simple PdCl2 complexes function as efficient precatalysts for ylide-substituted phosphines (YPhos). These complexes are readily synthesized from PdCl2 sources and form unprecedented monomeric PdCl2 complexes without the need for any additional coligand. Instead, these structures are stabilized through a unique bonding motif, in which the YPhos ligands bind to the metal through the adjacent phosphine and ylidic carbon site. DFT calculations showed that these bonds are both dative interactions with the stronger interaction originating from the electron-rich phosphine donor. This bonding mode leads to a remarkable stability even towards air and moisture. Nonetheless, the complexes readily form monoligated LPd(0) complexes and thus the active palladium(0) species in coupling reactions. Accordingly, the YPhos-PdCl2 complexes serve as highly efficient precatalysts for a series of C-C and C-X coupling reactions. Despite their simplicity they can compete with the efficiency of more complex and less stable precatalysts.

Synergistic effect of Thiourea and HCl on Palladium (II) recovery: An investigation on Chemical structures and thermodynamic stability via DFT

This work duly investigates the recovery of Pd (II) chlorocomplexes from industrial wastewater. Chemical structures and thermodynamic stabilities of the complex formed are evaluated via density functional theory (DFT). By applying synergistic solutions of thiourea mixed with hydrochloric acid (HCl), the stripping reaction of Pd (II) in the loaded Aliquat 336 occurs and Pd (II) chlorocomplexes coordinated thiourea ligands are formed, thus 80.19% of Pd (II) chlorocomplexes can be recovered. The aim of this study is to gain a better understanding of the stripping mechanisms and the structure of the complexes formed via the synergistic system. Such an understanding is still limited since little research has been conducted in this field. Owing to their molecular geometry, ligand coordination and donor groups play a vital role in the reactivity of palladium (II) complex. Quantum models have been developed to evaluate the chemical structure and thermodynamics stability of ((NH2)2CS·PdCl2) namely: (i) DFT with B3LYP/6-31g(d,p) and MP2/6-31g(d,p) basis set, (ii) MP2 with cc-pVTZ basis set and (iii) CCSD(T)/cc-pVTZ. Results demonstrate that the highest geometric stability exhibited is the structure of Pd-S bonding with 180° Cl-Pd-Cl. The distance (r) and angle (a) of the selected geometrical parameters for (NH2)2CS·PdCl2 complex are reported. Additionally, FTIR and UV–vis spectroscopies have been conducted to analyze the sampling solutions. Further, the calculated vibrational frequencies and experimental spectroscopic results show good agreement with the optimized geometry.

Catalytically active nanosized Pd9Te4 (telluropalladinite) and PdTe (kotulskite) alloys: first precursor-architecture controlled synthesis using palladium complexes of organotellurium compounds as single source precursors.

Several intermetallic binary phases of Pd–Te including Pd3Te2, PdTe, PdTe2, Pd9Te4, Pd3Te, Pd2Te, Pd20Te7, Pd8Te3, Pd7Te2, Pd7Te3, Pd4Te and Pd17Te4 are known, and negligible work (except few studies on PdTe) has been done on exploring applications of such phases and their fabrication at nanoscale. Hence, Pd(ii) complexes Pd(L1)Cl2 and Pd(L2-H)Cl (L1): Ph–Te–CH2–CH2–NH2 and L2: HO–2-C6H4–CH Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> N–CH2CH2–Te–Ph were synthesized. Under similar thermolytic conditions, complex Pd(L1)Cl2 with bidentate coordination mode of ligand provided nanostructures of Pd9Te4 (telluropalladinite) whereas Pd(L2-H)Cl with tridentate coordination mode of ligand yielded PdTe (kotulskite). Bimetallic alloy nanostructures possess high catalytic potential for Suzuki coupling of aryl chlorides, and reduction of 4-nitrophenol. They are also recyclable upto six reaction cycles in Suzuki coupling.

Catalytic Hydrogenation of Sorbic Acid using Pyrazolyl Palladium(II) and Nickel(II) Complexes as Precatalysts

ABSTRACT We have prepared several pyrazolyl palladium and nickel complexes ([(L1)PdCl2](1), [(L2) PdCl2](2), [(L3) PdCl2](3), [(L1) NiBr2](4), [(L2) NiBr2](5) and [(L3) NiBr2](6)) by reacting 3,5-dimethyMH-pyrazole (L1), 3,5-di-ferf-butyl-1ZÏ-pyrazole (L2) and 5-ferrocenyl-1Zf-pyrazole(L3) with [PdCl2(NCMe)2] or [NiBr2(DME)] to afford mononuclear palladium and nickel complexes, respectively. These complexes were then investigated as pre-catalysts in the hydrogenation of 2,4-hexadienoic acid (sorbic acid). The active catalysts from these complexes demonstrate significant activities under mild experimental conditions. Additionally, the active catalysts show that the hydrogenation of sorbic acid proceeds in a sequential manner, where the less hindered C=C bond (4-hexenoic acid) is preferentially reduced over the more hindered C=C bond (2-hexenoic acid). Keywords: Pyrazolyl catalysts, sorbic acid, hydrogenation, selectivity.

Synthesis, characterization, and coordination chemistry of a phenanthridine-containing N-heterocyclic carbene ligand

An N-heterocyclic carbene ligand precursor bearing a π-extended phenanthridine (3,4-benzoquinoline) unit is presented. The proligand was isolated as the imidazolium salt of chloride (1•HCl), bromide (1•HBr), or hexafluorophosphate (1•HPF6) counterions. These salts can be deprotonated and the carbene installed on silver centres using Ag2O as both a base and a source of metal ion. The resulting Ag(I) complex (1)AgCl can be used in a transmetalation reaction to generate a Pd(II) coordination complex (1)Pd(CH3CN)Cl2. The characterization and photophysical properties of these complexes is presented, along with a demonstration of the utility of (1)Pd(CH3CN)Cl2 in mediating a catalytic C-N cross-coupling reaction for the preparation of the pharmaceutical Piribedil.

Synthesis, structural characterization and antimicrobial activity of Schiff bases and benzimidazole derivatives and their complexes with CoCl2, PdCl2, CuCl2 and ZnCl2

In this study, new Schiff bases (H2L1 and H2L2) and benzimidazolylphenol derivatives (HL3 − HL5) derived from 5-chlorosalicylaldehyde and appropriate aminophenol and o-phenylenediamine derivatives including 4-methyl/4,5-dimethyl/4-chloro‑5-nitro groups were synthesized and characterized. CoCl2, PdCl2, CuCl2 and ZnCl2 complexes of the ligands were synthesized and characterized by using elemental analysis, molar conductivity, magnetic moment, FT-IR and NMR spectroscopy. In addition, the crystal structure of H2L1 and [Pd(L1)(CH3CN)]·H2O were determined by X-ray diffraction spectroscopy. Keto-enol tautomerism is observed in the Schiff base compounds according to spectral data. Antimicrobial activities of the compounds were tested toward six bacteria and three fungi. Some metal complexes (e.g. Co(II) complexes of the benzimidazole derivatives) showed higher activity towards the test microorganisms than the ligands. In addition, it is observed that the Co(II) complexes show in a wide range antimicrobial activity compared to the other complexes.

Synthesis, Structure, and Complexation of an S-Shaped Double Azahelicene with Inner-Edge Nitrogen Atoms.

An S-shaped double azahelicene (1) was synthesized in excellent yield by a palladium-catalyzed double dehydrogenative C-H coupling reaction. The stereochemistry of 1 was confirmed to be dl by single-crystal X-ray diffraction analysis. Selective formation of dl-1 was attributed to the isomerization of the kinetically controlled product (meso-1) into the more thermodynamically stable dl-1 under the applied reaction conditions. dl-1 can coordinate to palladium(II) in a bidentate trans-chelating fashion, which was confirmed by X-ray absorption fine structure (XAFS) as well as by X-ray photoelectron spectroscopy (XPS), diffuse reflectance (DR) UV/Vis, and far-infrared (FIR) absorption spectroscopy. Theoretical calculations of palladium complex 16 revealed a weak attractive interaction between palladium and carbon atoms on the central dimethoxynaphthalene core, which could facilitate a disproportionation between a trans-chelating (dl-1)⋅PdCl2 complex and PdCl2 to form 16.

Synthesis, Characterization and Antimicrobial Activity of Schiff Bases Including Three Hydroxy Groups and Their CoCl2, PdCl2, CuCl2 and ZnCl2 Complexes

AbstractFour Schiff bases, (3/4/2/4)‐{[(2‐hydroxy‐5‐methylphenyl)imino]methyl}benzene‐1,2/1,3/1,4/1,2‐diols (H3L1‐H3L4), derived from 2,3/2,4/2,5/3,4‐dihydroxybenzaldehydes and 2‐amino‐4‐methylphenol, and their CoCl2, PdCl2, CuCl2 and ZnCl2 complexes were synthesized and characterized. The structures of the complexes were suggested on the basis of elemental analysis, TGA, molar conductivity, magnetic moment, FT‐IR, UV‐vis and NMR spectroscopy. According to the analytical and spectral data, the ligands H3L1, H3L2 and H3L3 acted as tridentate, giving chelate structures in the complexes, via the C=N nitrogen and two phenolate oxygen atoms whereas H3L4 acted as bidentate. In addition, the crystal structure of H3L1 was determined by X‐ray diffraction. The spectral data show that there is keto‐enol tautomerization in the ligands and keto form is dominant in H3L1 and H3L3 while enol form is in H3L2 and H3L4. Antimicrobial activities of the compounds were tested against six bacteria and three fungi. [Zn(H2L1)Cl]⋅4H2O showed superior activity toward the fungi C. albicans, C. parapsilosis and C. tropicalis compared to H3L1 and the other compounds. Strong activity of H3L1, H3L2 and H3L3 was observed toward S. aureus whereas they showed weak activity to the other microorganisms.

Transition metal complexes of monodentate 2-oxazolines containing long chain alkyl groups. The crystal structure of trans-PdCl2(κ 1-N-rac-2-heptadecyl-4,5-dihydro-5-methyl-2-oxazole)2

Abstract The synthesis, characterisation and properties of several divalent metal complexes (Co, Ni, Pd) containing 2-oxazoline ligands L1–L3, appended with long chain alkyl and/or ester groups, is reported. The X-ray crystal structure aspects of one such complex, trans-PdCl2(rac-2-heptadecyl-4,5-dihydro-5-methyl-2-oxazole)2 (i.e. PdCl2(L1)2: 3), is described. This latter material contains one of the longest alkyl chains to be crystallographically characterised appended to an oxazoline ligand. The complexes reported herein represent the first transition metal derivatives of these high molecular weight, long chain and presumably low polarity monodentate oxazoline ligands. A combination of spectral and theoretical calculations (semi-empirical PM6(tm) level of theory) are used to support the proposed structure in the case of the hydrates of NiCl2 and CoBr2 complexes derived from L1. A trio of PdCl2 complexes of the ligand set are likewise detailed. Complex 3 is shown to be a useful pre-catalyst for the promotion of a Heck coupling reaction between bromobenzene and styrene under typical conditions.

Reactivity of Fluorinated-Chalcone Phosphines, RPEWO-F4, Induced by C–F Activation upon Coordination to PdCl2

The E phosphine ligands (R = Ph, o-Tol, Cy), abbreviated as RPEWO-F4, are stable in solution, but they develop a rich reactivity on coordination to PdCl2. The chelate P-olefin coordination to PdCl2 leads eventually to a Z conformation of the fluorinated-chalcone group o-C6F4CH═CHC(O)Ph. From there, a cyclization reaction occurs involving the C═O group and activation of a F atom, yielding a strongly chelated PdCl2(P-carbene) complex. The carbene carbon atom in the complex displays some electrophilicity, which is expressed in hydrolysis, ammonolysis, and oxidation (with peroxide) reactions, affording PdCl2 complexes with new P,C,O-pincer, P,C,N-pincer, or P,O-chelate fluorinated ligands. The C–F activation reactions are slow in comparison to the catalysis rates when the [PdCl2(RPEWO-F4)] complexes have been used in Negishi catalyses. Consequently, the reactivity discussed here is not expected to interfere with the interpretation of the data obtained in Pd-catalytic studies or processes, at least for fast transmetalating nucleophiles.