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1.
New N‐Alkyl‐substituted imidazolium salts as well as a series of their corresponding [Pd(NHC)(MA)2] complexes have been obtained by three routes in good yield. The previously reported synthesis for the analogous N‐aryl substituted [Pd(NHC)(MA)2] complexes has been improved. The N‐alkyl‐substituted [Pd(NHC)(MA)2] complexes are thermally more labile than their N‐aryl counterparts. Catalytic transfer semi‐hydrogenation of phenylpropyne resulted in good to excellent chemo‐ and stereo‐ selectivity conversion into (Z)‐phenylpropene. The size of the alkyl substituents correlates with the rate of hydrogenation in the sense that more bulky substituents give rise to faster transfer hydrogenation rates. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

2.
《Journal of Coordination Chemistry》2012,65(16-18):2787-2799
Abstract

Mononuclear trans-Pd(II)–NHC complexes (where NHC?=?N-heterocyclic carbene) bearing asymmetrically substituted NHC-ligand have been synthesized via transmetalation reaction between Ag(I)–NHC complexes and [Pd(NCCH3)2Cl2]. The NHC precursors are accessible in two steps by N-n-alkyl reactions of benzimidazole. The resultant benzimidazolium salts were deprotonated with Ag2O by in situ deprotonation to facilitate the formation of mononuclear Ag(I)–NHC complexes. Single-crystal structural study for Pd(II)–NHC shows that the palladium(II) ion exhibits a square-planar geometry of two NHC ligands and two chloride ions. The cytotoxicity study was investigated against breast cancer cell line (MCF-7). The Ag(I)–NHC complexes exhibit better activities than their corresponding Pd(II)–NHC complexes, whereas all benzimidazolium salts are inactive toward MCF-7 cancer cell line.  相似文献   

3.
The phenylimidorhenium(V) complexes [Re(NPh)X3(PPh3)2] (X = Cl, Br) react with the N‐heterocyclic carbene (NHC) 1,3‐diethyl‐4,5‐dimethylimidazole‐2‐ylidene (LEt) under formation of the stable rhenium(V) complex cations [Re(NPh)X(LEt)4]2+ (X = Cl, Br), which can be isolated as their chloride or [PF6]? salts. The compounds are remarkably stable against air, moisture and ligand exchange. The hydroxo species [Re(NPh)(OH)(LEt)4]2+ is formed when moist solvents are used during the synthesis. The rhenium atoms in all three complexes are coordinated in a distorted octahedral fashion with the four NHC ligands in equatorial planes of the molecules. The Re–C(carbene) bond lengths between 2.171(8) and 2.221(3) Å indicate mainly σ‐bonding between the NHC ligand and the electron deficient d2 metal atoms. Attempts to prepare analogous phenylimido complexes from [Re(NPh)Cl3(PPh3)2] and 1,3‐diisopropyl‐4,5‐dimethylimidazole‐2‐ylidene (Li?Pr) led to a cleavage of the rhenium‐nitrogen multiple bond and the formation of the dioxo complex [ReO2(Li?Pr)4]+.  相似文献   

4.
《Polyhedron》1987,6(5):1021-1025
Two novel series of complexes of types [La(DAPCH)X2]X and [La(DAPTC)X2]X (DAPCH = a potentially pentadentate ligand derived from 2,6-diacetylpyridine and carbohydrazide; DAPTC = a potentially tridentate ligand derived from 2,6-diacetylpyridine and thiocarbohydrazide; X = Cl, Br or NO3) have been synthesized and characterized by elemental analyses, conductance measurements and IR spectral data. All these complexes contain terminal hydrazinic nitrogen atoms with an unshared electron pair and may take part in nucleophilic condensations. Therefore, the reactions of these complexes with 2,6-diacetylpyridine have also been studied which cause ring closure and formation of macrocyclic ligand complexes. Two types of cyclic products, viz. mononuclear [La(mac)X2]X, [La(mac′)X2]X and binuclear [La2(mac)X4]X2, [La2(mac′)X4]X2 (mac- = macrocyclic ligand derived from DAPCH and 2,6-diacetylpyridine; mac′ = macrocyclic ligand derived from DAPTC and 2,6-diacetylpyridine; X = Cl, Br or NO3) have been isolated by carrying out the reactions by different methods. The IR spectra of these cyclic products are reported.  相似文献   

5.

Synthesis, spectral characteristics, and structure of palladium(I) carbonyl complexes containing anions of N-heterocyclic carboxylic acids and pyridine-2-sulfonic acid of the general formula [Pd(CO)(NHC-CO2)]n/[Pd(CO)(NHC-SO3)]n, where NHC is an N-heterocycle, were described. The resulting complexes can be attributed to a binuclear structure with bridging or terminal coordination of carbonyl ligands depending on the nature of the substituents in the heterocycle.

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6.
The synthesis of the complexes trans-[Pd(C6Cl5)X(CNMe)2] (X = Cl, Br, I, SCN) is described. These complexes undergo ready insertion of the CNMe ligand into the PdC6Cl5 bond to give pentachlorobenzimidoyl-bridged derivatives [Pd2{μ-C(C6Cl5NMe}2X2(CNMe)2].Aft terminal pentachlorobenzimidoyl complexes [Pd{μ-C(C6Cl5)NMe}X(CNR)2] can be isolated.  相似文献   

7.
On the Reaction of Halomethylphosphonium Halides, [R3PCYnX3–n]X, with Phosphanes, R′3P The results of the reaction of 19 different halomethylphosphonium halides, [R3PCYnX3–n]X (R = Ph, n-Bu, Me2N, Et2N; Y = H, F; X = Cl, Br, I; n = 0–2), with Ph3P, n-Bu3P, and (R2N)3P are presented. As reaction products bisphosphonium salts, [R3P? CYnX2–n? PR′3]X2, and phosphoranylphosphonium salts, [R3P=CY? PR′3]X, or reduced (halo)methyl-phosphonium salts, [R3PCHYnX2–n]X, are obtained. [Ph3PCBrF2]Br and [Bu3PCBrF2]Br react with R′3P by trans-alkylation forming [R′3PCBrF2]Br. The factors influencing the course of the reaction are discussed.  相似文献   

8.
A series of new benzimidazolium salts as N‐heterocyclic carbene (NHC) precursors has been synthesized. Reactions of these salts with Ag2O with varying metal‐to‐salt ratio facilitate the formation of a series of new binuclear and mononuclear Ag(I)–NHC complexes. All compounds were characterized using physicochemical and spectroscopic techniques. Single‐crystal X‐ray diffraction study reveals a binuclear structure for one of the complexes and a mononuclear one for two others. These complexes exist as cationic Ag(I)–NHC complexes with the chelation of carbene carbons to the silver centre in an almost linear manner. The compounds were screened for their anti‐bacterial activities against Staphylococcus aureus (ATCC 12600) as a Gram‐positive bacterium and Escherichia coli (ATCC 25922) as a Gram‐negative bacterium. The results show that both bacteria appear markedly inhibited. Furthermore, the results suggest the possibility of steric variation as a modulation of the anti‐bacterial activities. The nuclease activities of the compounds were assessed using gel electrophoresis and the results indicate that these complexes can cleave or degrade DNA and RNA via a non‐oxidative mechanism. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

9.
Novel acyclic Pd(II)‐N‐heterocyclic carbene (NHC) metallacrown ethers 5a , 5b have been synthesized. Reaction of the imidazolium salts bearing a long polyether chain with Ag2O afforded Ag‐NHC complexes, which then reacted as carbene transfer agent with PdCl2(MeCN)2 to give the desired acyclic Pd(II)‐NHC metallacrown ether complexes 5a and 5b . The 1H NMR and 13C NMR spectra show 5a and 5b exist as mixtures of cis and trans isomers in solution. The trans isomer of 5a was characterized by X‐ray diffraction, which clearly demonstrated two pseudo‐crown ether cavities in trans‐ 5a . Pd(II)‐NHC complexes 5a and 5b have been shown to be highly effective in the Suzuki‐Miyaura reactions of a variety of aryl bromides in neat water without the need of inert gas protection.  相似文献   

10.
The dihalomethanes CH2X2 (X=Cl, Br, I) were co‐crystallized with the isocyanide complexes trans‐[MXM2(CNC6H4‐4‐XC)2] (M=Pd, Pt; XM=Br, I; XC=F, Cl, Br) to give an extended series comprising 15 X‐ray structures of isostructural adducts featuring 1D metal‐involving hexagon‐like arrays. In these structures, CH2X2 behave as bent bifunctional XB/XB‐donating building blocks, whereas trans‐[MXM2(CNC6H4‐4‐XC)2] act as a linear XB/XB acceptors. Results of DFT calculations indicate that all XCH2–X???XM–M contacts are typical noncovalent interactions with estimated strengths in the range of 1.3–3.2 kcal mol?1. A CCDC search reveals that hexagon‐like arrays are rather common but previously overlooked structural motives for adducts of trans‐bis(halide) complexes and halomethanes.  相似文献   

11.
Cationic palladium(II) and rhodium(I) complexes bearing 1,2-diaryl-3,4-bis[(2,4,6-tri-t-butylphenyl)phosphinidene]cyclobutene ligands (DPCB–Y) were prepared and their structures and catalytic activity were examined (aryl = phenyl (DPCB), 4-methoxyphenyl (DPCB–OMe), 4-(trifluoromethyl)phenyl (DPCB–CF3)). The palladium complexes [Pd(MeCN)2(DPCB–Y)]X2 (X = OTf, BF4, BAr4 (Ar = 3,5-bis(trifluoromethyl)phenyl)) were prepared by the reactions of DPCB–Y with [Pd(MeCN)4]X2, which were generated from Pd(OAc)2 and HX in MeCN. On the other hand, the rhodium complexes [Rh(MeCN)2(DPCB–Y)]OTf were prepared by the treatment of [Rh(μ-Cl)(cyclooctene)2]2 with DPCB–Y in CH2Cl2, followed by treatment with AgOTf in the presence of MeCN. The cationic complexes catalyzed conjugate addition of benzyl carbamate to α,β-unsaturated ketones.  相似文献   

12.
By a reaction of [BiX6]3– with salts of various N-alkylated pyridine derivatives in 2M HX (X = Cl, Br), (N-BzPy)4[Bi2X10] complexes (X = Cl (1), Br (2), (4-MePyH)4[Bi2Cl10] (3)) are obtained and structurally characterized.  相似文献   

13.
Summary New complexes of the general formulae [MLA(H2O)2]-Cl2 (M=Ni or Cu), [MLAX2] (M=Co or Cu; X=Cl or Br), [NiLABr2]·H2O, [MLA] [MCl4] (M=Pd or Pt), [NiLB(H2O)2]Cl2·2H2O, [MLBCl2] (M=Co, Ni, Cu, Pd or Pt; X=Cl or Br) and [MLB] [MCl4] (M=Pd or Pt), where LA=N,N-ethylenebis(2-acetylpyridine imine) and LB=N, N-ethylenebis(2-benzoylpyridine imine), have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, t.g./d.t.g. methods, magnetic susceptibilities and spectroscopic (i.r., far-i.r., ligand field,1Hn.m.r.) studies. Monomeric pseudo-octahedral stereochemistries for the CoII, NiII and CuII complexes andcis square planar structures for the compounds [MLBX2] (M=Pd or Pt; X=Cl or Br) are assigned in the solid state. The molecules LA and LB behave as tetradentate chelate ligands in the CoII, NiII, CuII and Magnus-type PdII and PtII complexes, bonding through both the pyridine and methine nitrogen atoms. A bidentateN-methine coordination of the Schiff base LB is assigned in the [MLBX2] complexes (M=Pd or Pt; X=Cl or Br). The anomalous magnetic moment values of the CoII complexes are discussed.  相似文献   

14.
A number of Pd and Pt complexes were considered with similar structures and with the most stable states of the metal oxidation (+2 and +2, +4 for Pd and Pt, respectively). The majority of binuclear complex fragments were shown to have the planar metal coordination, whereas the anions lie in the symmetry center. The dimeric [M2X6]2? anions have unusual bent conformation with different angles of bending along the line joining the bridging metal atoms occupying the general position in the elementary cell.  相似文献   

15.
NHC adducts of the stannylene Trip2Sn (Trip=2,4,6‐triisopropylphenyl) were reacted with zero‐valent Ni, Pd, and Pt precursor complexes to cleanly yield the respective metal complexes featuring a three‐membered ring moiety Sn‐Sn‐M along with carbene transfer onto the metal and complete substitution of the starting ligands. Thus the easily accessible NHC adducts to stannylenes are shown to be valuable precursors for transition‐metal complexes with an unexpected Sn? Sn bond. The complexes have been studied by X‐ray diffraction and NMR spectroscopy as well as DFT calculations. The compounds featuring the structural motif of a distannametallacycle comprised of a [(NHC)2M0] fragment and Sn2Trip4 represent rare higher congeners of the well‐known olefin complexes. DFT calculations indicate the presence of a π‐type Sn–Sn interaction in these first examples for acyclic distannenes symmetrically coordinating to a zero‐valent transition metal.  相似文献   

16.
The reactions of 4N‐ethyl‐2‐[1‐(pyrrol‐2‐yl)methylidene(hydrazine carbothioamide ( 4 EL1 ) and 4N‐ethyl‐2[1‐(pyrrol‐2‐yl)ethylidene(hydrazine carbothioamide ( 4 EL2 ) with Group 12 metal halides afforded complexes of types [M(L)2X2] (M = Zn, Cd; L = 4 EL1, 4 EL2; X = Cl, Br, I; 1 – 6 , 14 – 19 ) and [M(L)X2] (M = Hg; L = 4 EL1, 4 EL2; X = Cl, Br, I; 7 – 9 , 20 – 22 ). In addition, reaction of 4 EL1 with salts of CuII, NiII, PdII and PtII afforded compounds of type [M(4 EL1–H)2] ( 10 – 13 ). The new compounds were characterized by elemental analysis, FAB mass spectrometry, IR and electronic spectroscopy and, for sufficiently soluble compounds, 1H, 13C and, when appropriate, 113Cd or 199Hg NMR spectrometry. The spectral data suggest that in their complexes with Group 12 metal cations, both thiosemicarbazones are neutral and S‐monodentate; and for [Zn(4 EL1)2I2] ( 3 ), [Cd(4 EL1)2Br2] ( 5 ) and [Hg(4 EL1)Cl2]2 ( 7 ) this was confirmed by X‐ray diffractometry. By contrast, in its complexes with CuII and Group 10 metal cations, 4 EL1 is monodeprotonated and S,N‐bidentate, as was confirmed by X‐ray diffractometry for [Ni(4 EL1–H)2] ( 11 ) and [Pd(4 EL1–H)2] ( 12 ).  相似文献   

17.
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.  相似文献   

18.
Pd(MME)Cl2 complex, where MME = methionine methyl ester, was synthesized and characterized by elemental analysis and spectroscopic techniques. [Pd(MME)(H2O)2]2+ interacts with some DNA constituents giving 1 : 1 and 1 : 2 complexes. The binuclear complexes having 4,4′-bipiperidine as a linker and involving [Pd(MME)(H2O)2]2+ and DNA constituents were investigated. The results show formation of [(H2O)(MME)Pd(Bip)Pd(MME)(H2O)]4+. Inosine, uracil, and thymine interact with the previously mentioned complex by substitution of the two coordinated water molecules. Formation constants of all possible mono- and binuclear complexes were determined and their speciation diagrams were evaluated.  相似文献   

19.
A new method for the synthesis of complexes PtIV(NHC)X4L (NHC is N-heterocyclic carbene of imidazole or benzimidazole series; X = Cl, Br; L is N-coordinated pyridine or NHC) based on mechanochemical oxidation of complexes PtII(NHC)X2L with dichloroiodobenzene (PhICl2) or pyridinium hydrobromide perbromide (PyHBr3) was proposed. Mechanochemical activation led to reduction in the synthesis time and increase in the selectivity of halogenation and yields of the target PtIV complexes (74–98%) as compared to the reaction in solutions.  相似文献   

20.
The aurophilicity exhibited by AuI complexes depends strongly on the nature of the supporting ligands present and the length of the Au–element (Au—E) bond may be used as a measure of the donor–acceptor properties of the coordinated ligands. A binuclear iron–gold complex, [1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene‐2κC2]dicarbonyl‐1κ2C‐(1η5‐cyclopentadienyl)gold(I)iron(II)(AuFe) benzene trisolvate, [AuFe(C5H5)(C27H36N2)(CO)2]·3C6H6, was prepared by reaction of K[CpFe(CO)2] (Cp is cyclopentadienyl) with (NHC)AuCl [NHC = 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene]. In addition to the binuclear complex, the asymmetric unit contains three benzene solvent molecules. This is the first example of a two‐coordinated Au atom bonded to an Fe and a C atom of an N‐heterocyclic carbene.  相似文献   

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