New direction in organopalladium chemistry: structure and reactivity of unsaturated hydrocarbon ligands bound to multipalladium units

Examination of the manner of interaction between Pd(0) and allylpalladium(II) complexes, both being involved as key intermediates in Pd-catalyzed allylic coupling, led us to discover a new role for such combinations in affecting the stereochemistry of the transformations. A similar investigation of the system involving Pd(0) and allenyl/propargyl complexes of Pd(II) led to the discovery of dinuclear Pd(I)bond;Pd(I) complexes containing bridging allenyl/propargyl ligands, which exhibited novel structural and reactivity aspects of great synthetic significance. A systematic comparison was made between the structure, stability, and reactivity of allyl and allenyl/propargyl ligands in dinuclear complexes and those in mononuclear counterparts. On the basis of MO calculations, coordination behavior specific to the ligands of the dinuclear complex is attributed to the occurrence of the back-donating interaction from filled Pdbond;Pd bonding orbitals to vacant ligand pi* orbitals. Similar bonding features are the origin of the ready synthesis of novel one-dimensional sandwich complexes composed of conjugated polyene ligands and linear polypalladium chains. A substitutionally labile dipalladium complex reacts with an equimolar amount of trienes or alkynes to give formal [4pi + 2sigma] or [2pi + 2sigma] adducts, respectively, which undergo further unique transformations with additional unsaturated substrates.     

Dinuclear Gold(I) Complexes Bearing N,N′‐Allyl‐Bridged Bisimidazolylidene Ligands

A novel N,N’‐allyl‐bridged bisimidazolium salt and a novel dinuclear Ag(I) and a Au(I) NHC complex are reported. Both metallacyclic complexes have a twisted structural shape due to the rigid allylic system and form two different isomers relating to the position of the double bonds. The allyl‐group shows photoisomerisation, but no reactivity towards bases for the additional coordination of Pd(II).     

Synthesis, structures, and solution dynamics of palladium complexes of quinoline-functionalized N-heterocyclic carbenes

A new type of quinoline-functionalized palladium N-heterocyclic carbene (NHC) complexes has been synthesized via silver transmetallation. The quinoline moiety was either directly attached to the imidazole ring or linked to it by a methylene group. NHCs with a methylene linker tend to form trans biscarbene complexes in the reaction of Pd(COD)Cl2, while NHCs without any linker form chelating NHC-quinoline (NHC-N) complexes. These two types of carbenes also react with [Pd(allyl)Cl]2 to give monodentate NHC palladium eta(3)-allyl chlorides [Pd(NHC)(allyl)Cl]. Fluxionality in the NMR time scale was observed for most complexes, and the origin of their dynamic behaviors was discussed for each type of structure. For [Pd(NHC)(allyl)Cl] with a relatively small wing tip group of the NHC, the fluxionality (selective line-broadening of (1)H NMR signals) is caused by selective eta(3)-eta(1)-eta(3) allyl isomerization. For NHC with a bulkier (t)Bu group, a different line-broadening pattern was observed and was ascribed to partially hindered Pd-C(carbene) bond rotation. For cationic chelating complexes [Pd(NHC-N)(allyl)]BF4, the dynamic exchange process likely originates from a dissociative boat-to-boat inversion of 7-membered palladacycles. Activation parameters were measured for this process. Crystal structures were reported for representative complexes in each category.     

Pd(II) complexes with polydentate nitrogen ligands. Molecular recognition and dynamic behavior involving Pd-N bond rupture. X-ray molecular structures of [[Pd(C6HF4)2](bpzpm)] and [[Pd(eta 3-C4H7)]2(bpzpm)] (CF3SO3)2 [bpzpm = 4,6-bis(pyrazol-1-yl)pyrimidine

The ligands 4,6-bis(pyrazol-1-yl)pyrimidine (bpzpm) and 4,6-bis(4-methylpyrazol-1-yl)pyrimidine (Me-bpzpm) were synthesized and their reactions with some palladium derivatives explored. Mononuclear or dinuclear neutral or cationic complexes were obtained by reaction of the ligands with 1 or 2 equiv of Pd(C6XF4)2(cod) (cod = 1,5-cyclooctadiene; X = F, H) or the palladium fragment [Pd(eta 3-2-Me-C3H4)(S)2]+ (S = acetone). The reaction of the dinuclear derivatives with 1 equiv of the respective free ligand immediately led to the regeneration of the mononuclear complexes. Except in the case of the synthesis of [[Pd(C6HF4)2][Pd(C6F5)2](bpzpm)], where two similar metallic groups are present, all attempts to obtain dinuclear asymmetric complexes with two different palladium fragments failed. Instead, the dinuclear symmetric complexes were formed. This result could be considered as an example of molecular recognition with the ligand acting as a ditopic receptor. This behavior is comparable to chemical symbiosis but in this case applied to the ligand rather than to the metal center as occurs normally. The polyfluorophenyl rings are situated on average in a perpendicular orientation with respect to the coordination plane. Their restricted rotation results in several atropoisomers for the complexes with m-C6HF4. Different cross-reaction experiments were carried out, and these showed the mobility of the metallic fragments, with the more difficult process being that involving the more strongly bonded polyfluorophenyl palladium groups. By means of 1H NMR variable temperature studies, the interconversion of the two isomers of [[Pd(eta 3-C4H7)]2-(bpzpm)]Tf2 (Tf = CF3SO3) was analyzed. In the case of [[Pd(eta 3-C4H7)](bpzpm)]Tf the existence of two processes, an intramolecular apparent allyl rotation and an intermolecular exchange of the allylpalladium fragments, has been demonstrated. Different delta Gc++ values at the coalescence temperatures have also been determined. An X-ray single-crystal analysis was carried out on [[Pd(eta 3-C4H7)]2(bpzpm)]Tf2, which crystallizes in the monoclinic system, space group I2/m, with a = 9.368(2), b = 16.191(3), c = 20.228(6) A, beta = 101.26(3), and Z = 4. Compound [[Pd(C6HF4)2](bpzpm)] crystallized in the triclinic system, space group P1, with a = 8.845(6), b = 12.6609(9), c = 12.826(3) A, alpha = 88.45(2), beta = 74.36(3), gamma = 89.32(2), and Z = 2.     

Mixed N-heterocycles/N-heterocyclic carbene palladium(II) allyl complexes as precatalysts for direct arylation of azoles with aryl bromides

A series of mixed N-heterocycles/N-heterocyclic carbene palladium(II) allyl complexes with general formula [(NHC)Pd(η³-allyl)]₂(μ₂-N-heterocycles)(BF₄)₂ were prepared in one pot based on anion metathesis of (NHC)Pd(η³-allyl)Cl complexes and then ligand replacement with N-heterocycles [N-heterocycles?=?pyrazine (pyz), 4,4′-bipyridine (bpy) and trans-4,4′-bipyridylethylene (bpe)]. The solid-state structures shown dinuclear structures with two palladium(II) centers holding together by bridged N-heterocycles. Initially investigation of the obtained complexes as precatalysts for direct CH bond arylation of azoles with aryl bromides was carried out.     

Redox reactions in palladium catalysis: on the accelerating and/or inhibiting effects of copper and silver salt additives in cross-coupling chemistry involving electron-rich phosphine ligands

Challenging a catalytic cycle: Pd(0) catalysts are readily oxidized by Cu and Ag salts to give dinuclear Pd(I) complexes and Cu(I) or Ag(I) cubanes (see scheme). The reactivities of the resulting Pd(I) dimers are consistent with several observations of additive effects in cross-coupling chemistry. The results indicate the possibility for alternative catalytic cycles involving dinuclear Pd(I) complexes over the currently accepted synergistic cycles involving Pd(0)/Pd(II) intermediates and Cu or Ag.     

Coordination features of bis(N-heterocyclic carbenes) and bis(oxazolines) with 1,3-alkylidene-2,4,6-trimethylbenzene spacers. Synthesis of the ligands and silver and palladium complexes

The synthesis of simple imidazolium-based ligand precursors containing a 1,3-alkylidene-2,4,6-trimethylbenzene spacer was examined and different synthetic protocols were applied depending on the nature of the alkylidene arm. For a methylene arm, simple dications 5a,b.2CI were obtained directly. The higher homologue counterparts were conveniently prepared by general multistep routes following a five-step sequence for ethylene dications 6a,b.2Br or a six-step sequence for propylene dications 7a,b.2Br in > or = 52% overall yield. Imidazolium salts based on the shorter methylene spacer were used to prepare palladium complexes (17-20) with N-heterocyclic carbenes via transmetallation from well-defined silver compounds or directly in basic conditions. In order to facilitate spectroscopic characterisation of the palladium species two [Pd(allyl)(bis-oxazoline)]+ (25-26) complexes with the same ligand bridge were synthesized. [PdX2bisL] complexes appeared in solution as mixtures of species, mononuclear with cis- or trans-geometry or oligomeric compounds. The reaction of [PdCl(allyl)]2 and micro-bis(carbene)(AgX)2 complexes in 1 : 1 or in 0.5 : 1 ratio leads to binuclear compounds [Pd2Cl2(allyl)2(micro-bis-carbene)] (19a,19b) and to very labile monomeric [Pd(allyl)(bis-carbene)]+ (20a,20b) compounds, respectively. The preparation of analogous [Pd(allyl)(bis-oxazoline)]+ complexes showed the formation of one of the four possible isomers. [Pd(allyl)(bis-oxazoline)]PF6 complexes were inactive as catalytic precursors in the allylic substitution reaction.     

Dinuclear palladium-azido complexes containing thiophene derivatives: reactivity toward organic isocyanides and isothiocyanates

Cyclopalladated tetranuclear Pd(II) complexes, [Pd2(micro-Cl)2(Y)]2 (Y = L1 or L2; H2L1 = di(2-pyridyl)-2,2'-bithiophene; H2L2 = 5,5'-di(2-pyridyl)-2,2':5',2'-terthiophene), containing two pyridyl-alpha, alpha'-disubstituted derivatives of thiophene were prepared. Treating these products with PR3 and subsequently with NaN3 produced the dinuclear Pd-azido complexes [(PR3)2(N3)Pd-Y-Pd(N3)(PR3)2] (Y = L1 or L2) or a cyclometallated complex [(PR3)(N3)Pd-Y'-Pd(N3)(PR3)] (Y' = C,N-L2). Reactions of these Pd-azido complexes with CN-Ar (Ar = 2,6-Me(2)C(6)H(3), 2,6-i-Pr(2)C(6)H(3)) or R-NCS (R = i-Pr, Et, allyl) led to the complexes containing end-on carbodiimido groups [(PMe3)2(N[double bond]C[double bond]N-Ar)Pd-Y-Pd(N[double bond]C[double bond]N-Ar)(PMe3)2] or S-coordinated tetrazole-thiolato groups {(PMe3)2[CN4(R)]S-Pd-Y-Pd-S[CN4)(R)](PMe3)2}. Interestingly, when treated with elemental sulfur, the carbodiimido complexes transformed into the cyclometallated derivatives, [(PMe3)(N[double bond]C[double bond]N-Ar)Pd-Y'-Pd(N[double bond]C[double bond]N-Ar)(PMe3)] (Y' = C,N-L1, C,N-L2). We also report the preparation of linear, thienylene-bridged dinuclear Pd complexes [L2(N3)Pd-X(or X')-Pd(N3)L2] (L = PMe3 or PMe2Ph; H2X = 2,2'-bithiophene or H2X' = 2,2':5',2'-terthiophene) and their reactivity toward organic isocyanide and isothiocyanates.     

Self-adaptable catalysts: substrate-dependent ligand configuration

Pd(II) allyl and Pd(0) olefin complexes containing the configurationally labile ligand 1,2-bis-[4,5-dihydro-3H-dibenzo[c-e]azepino]ethane were studied as models for intermediates in Pd-catalyzed allylic alkylations. According to NMR and DFT studies, the ligand prefers C(s) conformation in both eta3-1,3-diphenylpropenyl and eta3-cyclohexenyl Pd(II) complexes, whereas in Pd(0) olefin complexes it adopts different conformations in complexes derived from the two types of allyl systems in both solution and, as verified by X-ray crystallography, in the solid state. These results demonstrate that the Pd complex is capable of adapting its structure to the reacting substrate. The different structural preferences also provide an explanation for the behavior of 1,3-diphenyl-2-propenyl acetate and 2-cyclohexenyl acetate in Pd-catalyzed allylic alkylations using pseudo-C2 and pseudo-C(s) symmetric ligands.     

Allyl stannanes as electrophiles or nucleophiles in the palladium-catalyzed reactions with alkynes

The reactivity of the allyl stannanes can be inverted by changing the oxidation state of the catalyst from Pd(II) to Pd(0). Whereas with Pd(II) an anti nucleophilic attack of the allyl stannane on the alkyne takes place, the reaction with Pd(0) proceeds by oxidative addition to form (η³-allyl)palladium complexes leading to a formal syn addition to the alkyne. This mechanistic proposal is supported by DFT calculations.     

钯配合物对结核杆菌RecA intein蛋白质剪接的抑制作用

研究了5种钯配合物Pd(bipy)Cl₂, Pd(phen)Cl₂, [Pd(dien)Cl]Cl, trans-Pd(NH₃)₂Cl₂和cis-Pd(NH₃)₂Cl₂对结核杆菌RecA intein蛋白质剪接的抑制作用. 结果表明, trans-Pd(NH₃)₂Cl₂的抑制活性最好, IC₅₀=3.3×10^-5 mol/L. 钯配合物通过与intein的第一个氨基酸(半胱氨酸)配位, 从而抑制蛋白质的剪接活性. 荧光猝灭的动力学数据表明, 配体的大小会明显影响钯配合物与intein的相互作用, 配体越大, 作用越慢.     

Dinuclear Pd(II) and Pt(II) compounds bearing a bridging π-conjugated moiety: synthesis and reactivity toward alkynes and isocyanides

Abstract

Dinuclear Pd(II) halides that contain bridging π-conjugated groups, trans,trans-[(PR₃)₂(X)Pd–Y–Pd(X)(PR₃)₂] (X?=?Br; YH₂ = terpyridine, fluorenone, benzil, benzthiadiazole), were prepared by the oxidative addition of corresponding dihalo π-conjugated reagents to [Pd(styrene)(PR₃)₂]. Similar reactions involving dihalobenzil, dihalobithiophene, or dihaloterthiophene afforded dinuclear Pt(II) halides containing bridging π-conjugated groups. Additionally, when the dihalosilole derivatives {2,5-dibromo-1,1-dimethyl (or diphenyl)-3,4-diphenylsilole} reacted with [Pd(styrene)(PR₃)₂], mono or dinuclear Pd(II) complexes bearing a dimethyl (or diphenyl)-3,4-diphenylsilole group were obtained. π-Conjugation extension reactions of dinuclear bithiophene-bridged Pd(II) halides with HC≡C–R {R?=?SiPh₃, C(O)OMe} in the presence of CuI and HNEt₂ led to the unexpected formation of bis(acetylide) Pd(II) complexes of the form, [Pd(C≡C–R)₂(PR₃)₂] and bithiophene. In contrast, treatment of the dinuclear Pd(II) halides with two equiv of organic isocyanide resulted in isocyanide insertion into the Pd???C bonds to afford π-conjugation-extended dinuclear Pd(II) compounds bearing a π-conjugated moiety.     

Oxidative dinuclear addition of a PdI-PdI moiety to arenes: generation of μ-η3:η3-arene-Pd(II)2 species

We report the oxidative dinuclear addition of a Pd(I)-Pd(I) bond to arenes. The oxidative dinuclear addition products, which have a bi-π-allyl-type arene dipalladium(II) structure, were obtained from [2.2]paracyclophane, anthracene, tetracene, and pentacene. A systematic study of the reaction of [Pd(2)(CH(3)CN)(6)][BF(4)](2) with benzene and polyacenes showed that the larger polyacenes, tetracene and pentacene, afforded the oxidative dinuclear addition products, while benzene, naphthalene, and anthracene gave the π-sandwich Pd(I)-Pd(I) complexes.     

Coordination chemistry of dinucleating P2N2S ligands: preparation and characterization of cationic palladium complexes

The thioethers (4-tert-butyl-2,6-bis((2-(diphenylphosphino)ethylimino)methyl)phenyl)(tert-butyl)sulfane (tBuL3) and (4-tert-butyl-2,6-bis((2-(diphenylphosphino)ethylamino)methyl)phenyl)(tert-butyl)sulfane (tBuL4) react readily with [Pd(NCMe)2Cl2] to give the dinuclear palladium thiophenolate complexes [(L3)Pd2(Cl)2]+ and [(L4)Pd2(micro-Cl)]2+ (HL3=2,6-bis((2-(diphenylphosphino)ethylimino)methyl)-4-tert-butylbenzenethiol, HL4=2,6-bis((2-(diphenylphosphino)ethylamino)methyl)-4-tert-butylbenzenethiol). The chlorides in could be replaced by neutral (MeCN) and anionic ligands (NCS-, N3-, I-, CN-) to give the dinuclear PdII complexes [(L3)Pd2(NCMe)2]3+, [(L3)Pd2(SCN)2]+, [(L3)Pd2(N3)2]+, [(L3)Pd2(I)2]+, and [(L3)Pd2(CN)2]+. The acetonitrile ligands in are readily hydrated to give the corresponding amidato complex [(L3)Pd2(NHCOMe)]2+. All complexes were isolated as perchlorate salts and studied by infrared, 1H, and 31P NMR spectroscopy. In addition, complexes [ClO4].EtOH, [ClO4]2, [ClO4], [ClO4].EtOH, and [ClO4]2.MeCN.MeOH have been characterized by X-ray crystallography. The dipalladium complex was found to catalyse the vinyl-addition polymerization of norbornene in the presence of MAO (methylalumoxane) and B(C6F5)3/AlEt3.     

Design and self-assembly of ditopic and tetratopic cavitand complexes

The self-assembly of open ditopic and tetratopic cavitand complexes has been investigated by using monofunctionalized cavitand ligands and suitable metal precursors. In the case of ditopic complexes, self-assembly protocols, leading exclusively to the formation of both thermodynamically stable cis-Pt square-planar complexes 8 and 9 and the kinetically inert fac-Re octahedral complex 14, have been elaborated. The use of cis-[Pt(CH3)CN)2Cl2] as metal precursor led to the formation of monotopic trans-10 and ditopic trans-11 cavitand complexes, while cis-[Pt(dmso)2Cl2] afforded both cis-13 and trans-11 isomers. The self-assembly of tetratopic cavitand complexes has been achieved by using mononuclear [Pd(CH3CN)4(BF4)2] and dinuclear [M2(tppb)(OTf)4] (19: M = Pt; 20: M = Pd) metal precursors. Only the tetratopic dinuclear complexes 21 and 22 were stable. The ligand configuration with two phosphorus and two cavitand ligands at the metal centers is the most appropriate to build tetratopic cavitand complexes with sufficient kinetic stability.     

Pyrazole-3-carboxylates assisted N-heterocyclic carbene palladium complexes: synthesis,characterization, and catalytic activities towards arylation of azoles with arylsulfonyl hydrazides

Four mononuclear and dinuclear pyrazole-3-carboxylates assisted NHC–Pd complexes have been synthesized and characterized. Notably, the bridge-cleavage reactions of [Pd(μ-Cl)(Cl)(NHC)]₂ with 1H-pyrazole-3-carboxylic acid afforded dinuclear complexes [(NHC)Pd(μ-1H-pyrazolato-3-carboxylate)]₂, in which the 1H-pyrazolato-3-carboxylate was employed as a N^N^O dianionic chelating and bridging ligand. To further explore the structural features and catalytic properties of the complexes, 1-methyl-1H-pyrazole-3-carboxylic acid was introduced into the coordination with [Pd(μ-Cl)(Cl)(NHC)]₂ and the corresponding mononuclear complexes (NHC)PdCl(1-methyl-1H-pyrazole-3-carboxylate) were obtained. The catalytic properties of the complexes in desulfitative arylation of azoles with arylsulfonyl hydrazides were initially investigated.     

Carbon-carbon bond formation by electrophilic addition at the central carbon of the mu-eta(3)-allenyl/propargyl ligand on the Pd-Pd bond.

The mu-eta(3)-allenyl/propargyldipalladium complexes were synthesized by the reaction of the corresponding eta(1)-allenyl- or eta(1)-propargylpalladium complexes with Pd(2)(dba)(3). The X-ray diffraction analysis indicates that the dinuclear complex has a unique structure, in which two palladium, three carbon, two phosphorus, and one halogen atoms are in the same plane. These dinuclear complexes react with electrophiles, such as HCl or AcCl, at the central carbon of the mu-eta(3)-allenyl/propargyl ligand to give the mu-eta(3)-vinylcarbenedipalladium complexes. Intramolecular reaction proceeded smoothly to give cyclization products quantitatively. Addition of a catalytic amount of a palladium(0) complex dramatically accelerated the carbon-carbon bond formation. The MO calculations on the mu-eta(3)-allenyl/propargyl complexes indicated that the reaction proceeds via orbital control.     

ESI-MS studies of the dehydrogenative Heck reaction of furans with acrylates using benzoquinone as the reoxidant and DMSO as the solvent

Electrospray ionization mass spectrometry, subsequent MS/MS, and high-resolution mass spectrometry were used to study the dehydrogenative Heck reaction of 2-alkylfurans 1 with acrylates 2, using [Pd(OAc)(2)](3) as the precatalyst, benzoquinone (BQ) as the stoichiometric oxidant, and a mixture of DMSO and AcOH as the solvent. Complexation of [Pd(OAc)(2)](3) by DMSO afforded mononuclear and dinuclear Pd(II) species, which proved to be active catalysts for the C-H activation of 1. Mononuclear and dinuclear Pd(II) species seem also to be involved in the insertion of 2 into the furyl-Pd bond. The C-H activation of 2 and DMSO by mononuclear complexes was observed. The reaction leads to 5,5'-dialkyl-2,2'-bifuran 4 as a byproduct. Bifuryl-palladium, which is an intermediate in the formation of 4, showing the coordination of BQ, was obtained and characterized.     

Unusual reactivity of a sterically hindered diphosphazane ligand, EtN{P(OR)(2)}(2), (R = C(6)H(3)(Pr(I))(2)-2,6) towards (eta(3)-allyl)palladium precursors

The reactivity of (eta(3)-allyl)palladium chloro dimers [(1-R-eta(3)-C(3)H(4))PdCl](2) (R = H or Me) towards a sterically hindered diphosphazane ligand [EtN{P(OR)(2)}(2)] (R = C(6)H(3)(Pr(i))(2)-2,6), has been investigated under different reaction conditions. When the reaction is carried out using NH(4)PF(6) as the halide scavenger, the cationic complex [(1-R-eta(3)-C(3)H(4))Pd{EtN(P(OR)(2))(2)}]PF(6) (R = H or Me) is formed as the sole product. In the absence of NH(4)PF(6), the initially formed cationic complex, [(eta(3)-C(3)H(5))Pd{EtN(P(OR)(2))(2)}]Cl, is transformed into a mixture of chloro bridged complexes over a period of 4 days. The dinuclear complexes, [(eta(3)-C(3)H(5))Pd(2)(mu-Cl)(2){P(O)(OR)(2)}{P(OR)(2)(NHEt)}] and [Pd(mu-Cl){P(O)(OR)(2)}{P(OR)(2)(NHEt)}](2) are formed by P-N bond hydrolysis, whereas the octa-palladium complex [(eta(3)-C(3)H(5))(2-Cl-eta(3)-C(3)H(4))Pd(4)(mu-Cl)(4)(mu-EtN{P(OR)(2)}(2))](2), is formed as a result of nucleophilic substitution by a chloride ligand at the central carbon of an allyl fragment. The reaction of [EtN{P(OR)(2)}(2)] with [(eta(3)-C(3)H(5))PdCl](2) in the presence of K(2)CO(3) yields a stable dinuclear (eta(3)-allyl)palladium(I) diphosphazane complex, [(eta(3)-C(3)H(5))[mu-EtN{P(OR)(2)}(2)Pd(2)Cl] which contains a coordinatively unsaturated T-shaped palladium center. This complex exhibits high catalytic activity and high TON's in the catalytic hydrophenylation of norbornene.     

Mono- and dinuclear Pd(II) complexes of different salicylaldimine ligands as catalysts of transfer hydrogenation of nitrobenzene with cyclohexene and Suzuki-Miyaura coupling reactions

In this study, the synthesis, spectroscopic, catalytic, and electrochemical properties of salicylaldimine Schiff-base ligands (L_n) and their dinuclear Pd(II) complexes for L₁ and L₂ ligands with mononuclear Pd(II) complexes for L₃ and L₄ ligands were investigated. The ligands and their mono- or dinuclear Pd(II) complexes were characterized by FT-IR, UV-Vis, ¹H NMR and elemental analysis, as well as through magnetic susceptibility and spectroelectrochemical techniques. The catalytic studies showed that the introduction of tert butyl groups on the salicyl ring of the molecules increased the catalytic activity towards hydrogenation of nitrobenzene and cyclohexene in DMF at 25 and 45 °C. It was also observed that the steric hindered mono- and dinuclear Pd(II) complexes were thermally stable complexes and were not sensitive to air or the moisture. The complexes were easily prepared from cheap materials that could be used as versatile and efficient catalysts for different C-C coupling reactions (Suzuki-Miyaura reactions).