852573-38-7

Upstream product

• 626-60-8 3-Chloropyridine 
• 55528-77-3 trans-PdCl₂(S(C₂H₅)2)2 
• 14726-45-5 dichlorobis (methyl ethyl sulfide) palladium (II) 
• 51481-13-1 dichlorobis (diphenyl sulfide) palladium (II) 
• 66462-60-0 trans-[Pd(i-PrSMe)2Cl₂] 
• 914772-48-8 trans-[Pd(PhSMe)2Cl₂] 

Relevant academic research and scientific papers

Synthesis and characterization of novel PEPPSI type bicyclic (alkyl)(amino)carbene (BICAAC)-Pd complexes

A series of bicyclic alkylamino carbenes (BICAAC) (where N-aryl = dipp, mes, 2,6-dimethyl-4-(dimethylamino)phenyl, 5a–d) and their novel air- and moisture-resistant pyridine (pyridine, 4-dimethylaminopyridine) containing palladium Pd(II) complexes (6a–e) were synthetized and characterized. As novel examples of the PEPPSI (“pyridine enhanced precatalyst preparation stabilization and initiation”)-Pd compounds, the reported complexes have shown high activity in Mizoroki–Heck coupling reaction even at as low as 100 ppm loading (TON up to 10000). Kinetic studies revealed that reactions carried out in the presence of elemental mercury resulted decrease in activity. It indicates that the coupling reaction may have both molecular and Pd(0)-mediated catalytic paths.

Understanding existing and designing novel synthetic routes to Pd-PEPPSI-NHC and Pd-PEPPSI-PR3pre-catalysts

The reaction mechanism leading to the formation of cross-coupling palladium pre-catalysts of the PEPPSI family was investigated. Two intermediates were isolated and proved to be both suitable synthons to the pre-catalysts, with one permitting the design of a novel and greener user-friendly synthetic route. In light of this mechanistic understanding, the traditional one-pot method was shown to be possible using stoichiometric amounts of throw-away ligand, which represents a considerable synthetic improvement over the wasteful “in pyridine” approach.

One pot synthesis of ureas and carbamates via oxidative carbonylation of aniline-type substrates by CO/O2 mixture catalyzed by Pd-complexes

Abstract Carbonylation of aromatic amines by direct insertion of carbon monoxide is catalyzed by PdCl2(XnPy)2 complexes (where Py = pyridine, X = -CH3, -Cl; n = 0-2) and gives, depending on the conditions, ethyl N-phenylcarbamates or N,N′-diphenylureas. For carbonylation of aniline, a proper choice of XnPy ligands in PdCl2(XnPy)2 catalyst and application of molecular oxygen instead of nitrobenzene (conventionally used oxidant for carbonylations) allow to carry out the process under mild conditions with high yield and selectivity. The best results (75% yield of the main product with selectivity of catalyst above 90%) were obtained for the process catalyzed by PdCl2(2,4-Cl2Py)2 complex at 100°C and they were greatly improved in comparison to 41% yield and 68% selectivity obtained for CO/nitrobenzene used at 180°C.

Application of Pd(II) Complexes with Pyridines as Catalysts for the Reduction of Aromatic Nitro Compounds by CO/H2O

Many efforts have been undertaken to minimize the cost of large-scale conversion of aromatic nitro compounds to amines. Toward this end, application of CO/H2O as a reducing agent instead of molecular hydrogen seems to be a promising method, and the process can be catalyzed by Pd(II) complexes. In this work, the catalytic activity of square planar complexes of general structure PdCl2(XnPy)2 (where XnPy = pyridine derivative) was studied. Particular attention was paid to the effects of substituents both in the aromatic ring of XnPy (ligand) and the nitro compound to be reduced (YC6H4NO2). Incorporation of electron-withdrawing Y in the aromatic ring of YC6H4NO2 increases the conversion, indicating that the kinetics of this process is similar to that for the carbonylation of nitrobeznene by CO in the absence of water (described in J. Mol. Catal. A: Chem. 2011, 337, 9-16). Surprisingly, the incorporation of electron-withdrawing substituents into the aromatic ring of the XnPy ligand also increases the conversion of YC6H4NO2 (regardless of the structure of the YC6H4NO2 substrate).

Tuning of the catalytic properties of PdCl2(X nPy)2 complexes by variation of the basicity of aromatic ligands

The position and number of substituents in pyridine ligands (X nPy) were correlated with structural, physical, and chemical properties of PdCl2(XnPy)2 complexes applied as catalysts for the carbonylation of aromatic nitrocompounds (phosgene-free method of carbamates production). Thermal stability and catalytic activity of PdCl2(XnPy)2 complexes without steric hindrance increases with increasing XnPy's basicity whereas a decrease of thermal stability and catalytic activity of the complexes is observed for sterically crowded complexes (with the ortho-substituted XnPy). The complexes with X = Cl in meta- position of XnPy decompose to a mixture of PdCl2 and metallic Pd (similarly to complexes with Me nPy) whereas complexes with ortho-chlorine (in XnPy) decompose to the organopalladium products. Therefore, two different mechanisms of thermal decomposition are proposed for PdCl2(Cl nPy)2 and PdCl2(MenPy)2. The results of complex thermal and structural analysis of a series of PdCl 2(XnPy)2 complexes allow us to get insight into the mechanism of nitrobenzene (NB) carbonylation catalyzed by PdCl 2(XnPy)2 at 150-180 °C. We conclude that the electron transfer from Pd(0) to nitrobenzene is the rate determining step of catalytic cycle of NB carbonylation.

Crystal structure, electronic properties and cytotoxic activity of palladium chloride complexes with monosubstituted pyridines

Palladium(ii) complexes attract great attention due to their remarkable catalytic and biological activity. In the present study X-ray characterization, UV-Vis and Time-Dependent Density Functional Theory (TD-DFT) calculations for six PdCl2(XPy)2 complexes (where: Py = pyridine; X = H, CH3 or Cl) were applied in order to investigate substituent effects on their crystal structures and electronic properties and to combine the results with their catalytic and cytotoxic activity. The structures of complexes PdCl2(3-MePy)2, PdCl2(4-MePy)2 and PdCl2(2-ClPy)2, have been described for the first time and we compared our results with available data for the whole series of six complexes. All compounds exhibit a square planar coordination geometry in which the palladium ion coordinates two nitrogen atoms of pyridine ligands and two chlorine atoms in trans positions. For complexes with ortho substituted XPy ligands a cis disposition of substituents takes place, whereas for other ligands: 3-MePy and 3-ClPy - the substituents are in trans positions. For XPy the energies of π-π* and n-π* transitions depend on the position and nature of the X substituent in the XPy ring. After complex formation a hipsochromic shift (24-34 nm) of π-π* and a bathochromic shift of n-π* bands are observed. The UV-Vis spectra of PdCl 2(XPy)2 confirm that square planar coordination geometry of complexes I-VI and two dπ-π* transitions are expected. With the help of the TD-DFT calculations we proved that dπ-π* transitions in solutions of PdCl2(XPy)2 complexes result from MLCT (metal-to-ligand charge transfer) with contribution from chlorine atoms to palladium. We also studied substituent effects on cytotoxic properties of Pd(ii) complexes against the human breast cancer cell line MCF7, the human prostate cancer cell line PC3, and the human T-cell lymphoblast-like cell line CCRF. The studied complexes were the most active against the CCRF cell line and less or even no cytotoxic effect was observed for PC3 cells. Complexes with MePy ligands showed increased cytotoxic activity compared to unsubstituted pyridine ligands.

Catalytic activity of PdCl2 complexes with pyridines in nitrobenzene carbonylation

Synthesis of square planar palladium(II) complexes of general structure PdCl2(XnPy)2 (where: Py = pyridine; X nPy = 2-MePy; 3-MePy; 4-MePy; 2,4-Me2Py; 2,6-Me 2Py; 2-ClPy; 3-ClPy and 3,5-Cl2Py) has been performed in order to study activity of these complexes as catalysts of nitrobenzene (NB) carbonylation - a process of industrial importance leading to production of ethyl N-phenylcarbamate (EPC). Electron withdrawing/electron donating properties of XnPy ligands (described by experimentally determined acidity parameter pKa) have been correlated with activities of PdCl 2(XnPy)2 complexes during NB carbonylation in presence of catalytic system PdCl2(XnPy) 2/Fe/I2/XnPy. We observed that conversions of substrates and yields of EPC increase within increasing basicity of X nPy ligand (for not sterically hindered XnPy's). On the basis of current work and our previous studies a detailed mechanism of catalytic carbonylation of NB is proposed.

Supramolecular chemistry of halogens: Complementary features of inorganic (M-X) and organic (C-X′) halogens applied to M-X...X′-C halogen bond formation

Electronic differences between inorganic (M-X) and organic (C-X) halogens in conjunction with the anisotropic charge distribution associated with terminal halogens have been exploited in supramolecular synthesis based upon intermolecular M-X...X′-C halogen bonds. The synthesis and crystal structures of a family of compounds trans-[MCl2(NC5H 4X-3)2] (M = Pd(II), Pt(II); X = F, Cl, Br, I; NC 5H4X-3 = 3-halopyridine) are reported. With the exception of the fluoropyridine compounds, network structures propagated by M-Cl...X-C halogen bonds are adopted and involve all M-Cl and all C-X groups, M-Cl...X-C interactions show Cl...X separations shorter than van der Waals values, shorter distances being observed for heavier halogens (X). Geometries with near linear Cl...X-C angles (155-172°) and markedly bent M-Cl...X angles (92-137°) are consistently observed. DR calculations on the model dimers {trans-[MCl2(NH3)(NC 5H4X-3)]}2 show association through M-Cl...X-C (X ≠ F) interactions with geometries similar to experimental values. DFT calculations of the electrostatic potential distributions for the compounds trans-[PdCl2(NC5H4X-3)2] (X = F, Cl, Br, I) demonstrate the effectiveness of the strategy to activate C-X groups toward halogen bond formation by enhancing their electrophilicity, and explain the absence of M-Cl...F-C interactions. The M-Cl...X-C halogen bonds described here can be viewed unambiguously as nucleophile-electrophile interactions that involve an attractive electrostatic contribution. This contrasts with some types of halogen-halogen interactions previously described and suggests that M-Cl...X-C halogen bonds could provide a valuable new synthon for supramolecular chemists.