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1.
Yu Sun 《Inorganica chimica acta》2006,359(15):4807-4810
3(5)-Pyrazolyl substituted triphenylphosphines have been investigated as ligands for the palladium catalyzed Heck reaction of aryl halides with styrene. Catalysts formed in situ from those phosphines and PdII(OAc)2 are comparable in activity and selectivity with the corresponding pre-synthesized Pd(II) complexes, while Pd2(dba)3 has turned out to be a less suitable palladium source. Among the ligands investigated, the bidentate P,N-ligand 2-[3(5)-pyrazolylphenyl]diphenylphosphine has shown the highest activities for the coupling of bromobenzene with styrene in the presence of PdII(OAc)2. In the presence of 1 equiv. of nBu4NI as the additive, unreactive 4-chloroacetophenone also undergoes Heck coupling with styrene.  相似文献   

2.
The novel palladium phosphino-thioether P-S chelate complex, [PdCl2{MeSC6H4-2-(CH2PPh2)}] (3) is a highly efficient catalyst for the olefinic coupling of aryl bromo and iodo compounds to olefins under aerobic conditions, leading to more than 106 turnovers for the reactions with bromo and iodo benzenes.  相似文献   

3.
Ligands containing the 2-organochalcogenomethylpyridine motif with substituents in the 4- or 6-position of the pyridyl ring, R4,R6-pyCH2ER1 [R4 = R6 = H, ER1 = SMe (1), SeMe (2), SPh (6), SePh (7); R4 = Me, R6 = H, ER1 = SMe (3), SPh (8), SePh (9); R4 = H, R6 = Me, ER1 = SMe (4), SPh (10), SePh (11); R4 = H, R6 = Ph, ER1 = SMe (5), SPh (12), SePh (13)] are obtained on the reaction of R4,R6-pyMe with LiBun followed by R1EER1. On reaction with PdCl2(NCMe)2, the ligands with a 6-phenyl substituent form cyclopalladated species PdCl{6-(o-C6H4)pyCH2ER1-C,N,E} (5a, 12a, 13a) with the structure of 13a (ER1 = SePh) confirmed by X-ray crystallography; other ligands form complexes of stoichiometry PdCl2(R4,R6-pyCH2ER1). Complexes with R6 = H are monomeric with N,E-bidentate configurations, confirmed by structural analysis for 3a (R4 = Me, ER1 = SMe), 7a (R4 = H, ER1 = SePh) and 9a (R4 = Me, ER1 = SePh). Two of the 6-methyl substituted complexes examined by X-ray crystallography are oligomeric with trans-PdCl2(N,E) motifs and bridging ligands, trimeric [PdCl2(μ-6-MepyCH2SPh-N,S)]3 (10a) and dimeric [PdCl2(μ-6-MepyCH2SePh-N,Se)]2 (11a). This behaviour is attributed to avoidance of the Me···Cl interaction that would occur in the cis-bidentate configuration if the pyridyl plane had the same orientation with respect to the coordination plane as observed for 3a, 7a and 9a [dihedral angles 8.0(2)-16.8(2)°]. When examined as precatalysts for the Mizoroki-Heck reaction of n-butyl acrylate with aryl halides in N,N-dimethylacetamide at 120 °C, the complexes exhibit the anticipated trends in yield (ArI > ArBr > ArCl, higher yield for electron withdrawing substituents in 4-RC6H4Br and 4-RC6H4Cl). The most active precatalysts are PdCl2(R4-pyCH2SMe-N,S) (R = H (1a), Me (3a)); complexes of the selenium containing ligands exhibit very low activity. For closely related ligands, the changes SMe to SPh, 6-H to 6-Me, and 6-H to 6-Ph lead to lower activity, consistent with involvement of both the pyridyl and chalcogen donors in reactions involving aryl bromides. The precatalyst PdCl2(pyCH2SMe-N,S) (1a) exhibits higher activity for the reaction of aryl chlorides in Bun4NCl at 120 °C as a solvent under non-aqueous ionic liquid (NAIL) conditions.  相似文献   

4.
Reactions of 1,3-C6H4(CH2Br)2 and the thiols HSCH2CH2Rfn (Rfn = (CF2)n−1CF3; n = 8, 10), or the dithiol 1,3-C6H4(CH2SH)2 and ICH2CH2Rfn, in the presence of carbonate or NaOEt (70-78 °C) give the title ligands 1,3-C6H4(CH2SCH2CH2Rfn)2 (4-Rf8, 58-61%; 4-Rf10, 49-50%). Reactions of 4-Rfn and Pd(OC(O)CF3)2 or (PhCN)2Pd(Cl)2 (80 °C) afford the title complexes (n/X = 8/OC(O)CF3 (5-Rf8), 44%; 10/OC(O)CF3, 58%; 8/Cl (6-Rf8), 45%; 10/Cl, 79%). Both 5-Rf8 and 6-Rf8 are effective catalyst precursors for the Heck reaction of iodobenzene and methyl acrylate (0.21-0.23 mol%, DMF, i-Pr2NEt, 100-125 °C). However, no active catalyst can be recycled by a subsequent extraction with fluorous solvents. Rather, activity remains in the reddish DMF phase, and is quenched by the addition of mercury. Palladium nanoparticles are visible by transmission electron microscopy. These, or low valent species derived therefrom, are believed to be the active catalysts, in accord with other recent studies involving related non-fluorous and fluorous palladacycles. The CF3C6F11/toluene partition coefficients of representative compounds are determined.  相似文献   

5.
A series of palladium complexes of the type [Pd(phPS2)(PAr3)] (phPS2) = [PhP(C6H4-2-S)2]2− have been synthesized in good yields and their crystal structures determined. Heck coupling reactions were carried out using the [Pd(phPS2)(PPh3)] (1), [Pd(phPS2){P(C6H4-4-Cl)3}] (2), [Pd(phPS2){P(C6H4-4-F)3}] (3), [Pd(phPS2){P(C6H4-4-CF3)3}] (4), [Pd(phPS2){P(C6H4-4-Me)3}] (5) and [Pd(phPS2){P(C6H4-4-OMe)3}] (6) complexes as catalyst precursors in order to examine the potential effect of the para-substituted triarylphosphines in the reaction of bromobenzene and styrene.  相似文献   

6.
A series of di-NHC ligands with alkyl bridges of different chain lengths (n = 2-4) and their bi-palladium complexes (4, 5 and 6) have been prepared. The molecular structure of 4 and 6 were determined by X-ray diffraction studies. The structures of complex 4 consist of two pseudo-square-planar subunits in a trans configuration, however 6 consist of two subunits in a cis configuration with π-π stacking between two pyridines. The influence of the different bridges on the structure and reactivity of the complexes has been studied. The catalytic activity of the new binuclear palladium complexes was successfully tested in the Mizoroki-Heck reaction of styrene with bromobenzene. The complex with 2 and 4 carbon linker gave higher yield, while the one with 3 carbon linker gave better regioselectivity.  相似文献   

7.
The potentially tridentate ligand 2,6-bis[(3-methylimidazolium-1-yl)methyl]pyridine dibromide reacts readily with silver(I) oxide in dichloromethane or dimethylsulfoxide to give a dinuclear silver(I)-carbene complex that was isolated as the tetrafluoroborate salt. Single crystal X-ray crystallography shows that each silver(I) ion is bridged by two ligands bonding through the carbene donors. Treatment of the silver(I) complex with suitable palladium(II) precursors gave the complexes PdCl[(CNC)]BF4 and [PdMe(CNC)]BF4 (CNC=2,6-bis[(3-methylimidazolin-2-yliden-1-yl)methyl]pyridine), in which the pyridyl and both carbene moieties are coordinated to a single palladium(II). The palladium(II) complexes have been fully characterised, including X-ray crystallography, and exhibit good activities in the Heck coupling reaction of 4-bromoacetophenone and n-butyl acrylate.  相似文献   

8.
The dinuclear V(V) complexes (VOL)2O (L = SAE (1), SAMP (2), SAP (3)) have been synthesized from VO(acac)2 and the corresponding tridentate ligands LH2 in methanol under reflux conditions and subsequent air oxidation in organic solvent. They have been characterized by IR and NMR spectroscopy, by thermogravimetric analysis, and by single crystal X-ray diffraction for 1 and 2. DFT calculations were carried out for a better understanding of the vibrational pattern, principally the V-O related vibrations. Complex [VO(SAP)]2O (3) catalyzes the epoxidation of cyclooctene by TBHP in water in the absence of any added solvent with good selectivity.  相似文献   

9.
A new thiophene-functionalized benzimidazolium salt (2) has been prepared by reacting N-methylbenzimidazole with 2-bromomethylthiophene (1), which in turn was obtained by bromination of 2-thiophenemethanol with PBr3. Subsequent reaction of salt 2 with Pd(OAc)2 afforded the cis-configured bis(carbene) Pd(II) complex (cis-3), which in solution exists as an inseparable mixture of cis-anti and cis-syn-rotamers in a 3.5:1 ratio. All new compounds have been fully characterized by spectroscopic and spectrometric methods. A preliminary catalytic study shows that cis-3 is highly active in the Suzuki-Miyaura coupling of aryl bromides with phenylboronic acid in/on water as environmentally benign reaction media.  相似文献   

10.
Schiff bases of 2-hydroxybenzophenone (HBP) (C6H5)(2-HOC6H4)CN(CH2)nEAr (L1/L2: E = S, Ar = Ph, n = 2/3; L3/L4: E = Se, Ar = Ph, n = 2/3; L5/L6: E = Te, Ar = 4-MeOC6H4, n = 2/3) and their complexes [PdCl(L-H)] (L = L1L6; 1, 2, 3, 5, 7, 11), [PtCl(L3-H/L5-H)] (4/8), [PtCl2(L4/L6)2] (6/12), [(p-cymene)RuCl(L5/L6)]Cl (9/13) and [HgBr2(L5/L6)2] (10/14) have been synthesized and characterized by proton, carbon-13, selenium-77 and tellurium-125 NMR, IR and mass spectra. Single crystal structures of L1, 1, 3, 4, 5 and 7 were solved. The Pd-E bond distances (Å): 2.2563(6) (E = S), 2.3575(6)−2.392(2) (E = Se); 2.5117(5)−2.5198(5) (E = Te) are near the lower end of the bond length range known for them. The Pt-Se bond length, 2.3470(8) Å, is also closer to the short values reported so far. The Heck and Suzuki reaction were carried out using complexes 1, 3, 5 and 7 as catalysts under aerobic condition. The percentage yields for trans product in Heck reaction were found upto 85%.  相似文献   

11.
Different forms of metallic palladium (wire, foil and sponge) have been tested as potential catalysts in the Suzuki-Miyaura cross-coupling. All samples showed to be catalytically active for both electron-poor and electron-rich aryl bromides combined with a variety of arylboronic acids. Palladium wire has been recycled six times without decrease of activity. A series of poisoning experiments demonstrated that the true catalyst is a soluble form of palladium arising from a leaching process. Interestingly, metal leaching from palladium foil has been clearly evidenced by SEM.  相似文献   

12.
A series of new nickel complexes and palladium complexes bearing ortho-phenoxy modified anilido-imine ligands have been synthesized and characterized. X-ray diffraction analyses of the single crystal structures reveal that there are no direct metal-O interactions in all of the complexes. The steric hindrance of complexes has an importance influence on their coordinated geometries. The bulky complexes with 2,6-diisopropylphenyl substituent exist as a dimers with bromine-bridged structure while those with 2,6-dimethylphenyl or phenyl substituents adopt a distorted tetrahedral geometry with four nitrogen atoms of two anilido-imine ligands. The nickel complexes exhibited high activity up to 7.33 × 106 g/(mol of Ni · h) and palladium complexes showed very high activity up to 2.63 × 108 g/(mol of Pd · h) for norbornene polymerization with methylaluminoxane as cocatalyst. The nickel catalysts were attempted to polymerize ethylene at atmosphere pressure, however, only oligomers were produced.  相似文献   

13.
New Pd(II) and Pt(II) complexes [ML2] (HL=a substituted 2,5-dihydro-5-oxo-1H-pyrazolone-1-carbothioamide) have been synthesized by reacting K2MCl4 (M=Pd, Pt) or Pd(OAc)2 with beta-ketoester thiosemicarbazones. The structures of seven of these complexes were determined by X-ray diffraction. Although all exhibit a distorted square-planar coordination with trans- or (in one case) cis-[MN2S2] kernels, their supramolecular arrangements vary widely from isolated molecules to 3D-networks. The in vitro antitumoral assays performed with two HL ligands and their metal complexes showed significant cytostatic activity for the latter, with the most active [ML2] derivative (a palladium complex) being about sixteen times more active than cis-DDP against the cisplatinum-resistant cell line A2780cisR.  相似文献   

14.
Reaction of [Mo(O)Cl(CNMe)4]+ with the linear tetraphos ligand meso and rac prP4 leads to a mixture of [Mo(O)Cl(κ4-meso-prP4)]+ and [Mo(O)Cl(CNMe)(κ3-rac-prP4)]+ which are identified by X-ray structural analysis and/or 31P NMR spectroscopy. In the meso κ4-product both of the phenyl groups of the central phosphorus atoms are oriented towards the oxo ligand whereas in the rac κ3-product one of these phenyl groups is oriented to the oxo and the other to the chloro ligand. The origin of the different coordination modes lies in the different steric demands of the oxo and chloro ligands. The influences of the steric interactions are enhanced by the fact that exchange of the fourth isonitrile is difficult. This hypothesis is supported by the preparation of the complex [Mo(O)Cl(CNMe)(dpepp)]PF6 whose isonitrile ligand is inert towards exchange by monophosphines, even under drastic conditions.  相似文献   

15.
Two isomers of the N,O-coordinated acetylpyrrolyl complex [Ru(PPh3)2(CO)(NC4H3C(O)CH3)H] {cis-N,H (1) and trans-N,H (2)} have been prepared as models for catalytic intermediates in the Murai reaction. Complex 2 isomerises to 1 upon heating via a dissociative pathway (ΔH = 195 ± 41 kJ mol−1; ΔS = 232 ± 62 J mol−1 K−1); the mechanism of this process has been modeled using density functional calculations. Complex 2 displays moderate catalytic activity for the Murai coupling of 2′-methylacetophenone with trimethylvinylsilane, but 1 proved to be catalytically inactive under the same conditions.  相似文献   

16.
The ability of organoiridium derivatives of catalyzing oligomerization and polymerization of terminal alkynes is markedly influenced by the nature of non-participative ligands coordinated to the metal. The dimeric species [Ir(cod)Cl]2 and [Ir(cod)(OMe)]2 (cod = 1,5-cyclooctadiene) as well as the phosphine complexes HIr(cod)(PR3)2 (PR= PPh3, P(p-MeOC6H4)3, P(o-MeOC6H4)Ph2, PCyPh2) catalyze the polymerization reaction, whereas the diphosphine derivatives HIr(cod)(P-P) (P-P = Ph2P(CH2)nPPh2 (n = 1-4), o-C6H4(PPh2)2) promote the regioselective formation of 1,2,4-trisubstituted benzenes. On the other hand, the iridium complexes with nitrogen chelating ligands Ir(cod)(N-N)X and Ir(hd)(N-N)X (hd = 1,5-hexadiene; N-N = 1,10-phenanthroline and substituted derivatives; X = halogen) catalyze alkynes polymerization. In most cases one catalytic reaction predominates over the other possible routes, so that polymerization often takes place in the absence of oligomerization side reactions, and conversely cyclotrimerization is rarely accompanied by formation of either polyene or dimers.  相似文献   

17.
Compounds 1-6 of the type MoO2X2L2 (X=F, Cl, Br; L=OPMePh2, OPPh3) have been prepared in order to investigate the variation in catalytic activity with changes in electronic and steric properties. All six complexes catalyze the epoxidation of cyclohexene with tert-butylhydroperoxide, and the species with X=Cl and L=OPMePh2 (2) displays the best activity with 83% conversion and 90% selectivity in one hour at ambient atmosphere. These inexpensive and easily prepared dioxo catalysts are stable to air and water. Reactions of the dioxo compounds with H2O2 and t-BuOOH have also been carried out. The structures of MoO2F2(OPMePh2)2 (1) and the product of its reaction with H2O2, MoO(O2)2(OPMePh2)2 (7) have been solved by single crystal X-ray diffraction.  相似文献   

18.
Iminophosphinite pincer palladium complexes were synthesized and evaluated as potential catalysts in the Suzuki coupling reactions of phenylboronic acid and various aryl halides. The iminophosphinite ligands were synthesized through condensation reactions between 2-bromo-3-hydroxybenzaldehyde and 2,4,6-trimethylaniline and 2,6-diisopropylaniline, followed by phosphorylation with chlorodiphenylphosphine and chlorodicyclohexylphosphine. Oxidative addition of the pincer ligands to Pd2(dba)3 afforded palladium iminophosphinite complexes [(2-(CHNR)-6-(OPR′2)C6H3)PdBr] (R = 2,6-iPr2C6H3, R′ = Ph (2a) or Cy (2b); R = 2,4,6-Me3C6H2, R′ = Ph (2c) or Cy (2d)). Reaction of 2b and silver trifluoroacetate gave the corresponding iminophosphinite palladium trifluoroacetate (3). The solid state structures of 2a, 2d, and 3 were determined by X-ray single crystal diffraction studies.  相似文献   

19.
The first chiral bis(pyridine) N-C(H)-N pincer ligand, (5S,7S)-1,3-bis(6,6-dimethyl-5,6,7,8-tetrahydro-5,7-methanquinolin-2-yl)benzene (HL) has been synthesized and characterized by a thorough 1H NMR analysis. Reaction of HL with K2[PtCl4] in acetic acid gives [Pt(L)Cl] (1), where L acts as a tridentate N-C-N pincer ligand. The analogous palladium(II) derivatives [Pd(L)Cl] (2), and [Pd(L)(OAc)] (3), were first prepared through a transmetalation reaction between Pd(OAc)2 and the organomercury compound [Hg(L)Cl] (4). The structures of compounds 1 (Pt) and 2 (Pd), as determined by X-ray diffraction, are reported and compared. Compound 2 can also be obtained from Na2[PdCl4] and HL in refluxing acetic acid, i.e., under the same conditions used for compound 1. Apparently, this is the first palladium pincer derivative of a 1,3-bis(pyridyl)benzene ligand synthesized by direct C-H activation.The neutral complexes 1-3 are catalysts of modest activity, but devoid of enantioselectivity in the Heck reaction between iodobenzene and methyl acrylate and in the aldol condensation of benzaldehyde with methyl isocyanoacetate.  相似文献   

20.
Palladium [PdCl2(L)] complexes with N-alkylpyridylpyrazole derived ligands [2-(5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L1), 2-(1-ethyl-5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L2), 2-(1-octyl-5-trifluoromethyl-1H-pyrazol-3-yl)pyridine (L3), and 2-(3-pyridin-2-yl-5-trifluoromethyl-pyrazol-1-yl)ethanol (L4) were synthesised. The crystal and molecular structures of [PdCl2(L)] (L = L2, L3, L4) were resolved by X-ray diffraction, and consist of monomeric cis-[PdCl2(L)] molecules. The palladium centre has a typical square-planar geometry, with a slight tetrahedral distortion. The tetra-coordinate metal atom is bonded to one pyridinic nitrogen, one pyrazolic nitrogen and two chlorine ligands in cis disposition. Reaction of L (L2, L4) with [Pd(CH3CN)4](BF4)2, in the ratio 1M:2L, gave complexes [Pd(L)]2(BF4)2. Treatment of [PdCl2(L)] (L = L2, L4) with NaBF4 and pyridine (py) and treatment of the same complexes with AgBF4 and triphenylphosphine (PPh3) yielded [Pd(L)(py)2](BF4)2 and [Pd(L)(PPh3)2](BF4)2 complexes, respectively. Finally, reaction of [PdCl2(L4)] with 1 equiv of AgBF4 yields [PdCl(L4)](BF4).  相似文献   

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