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1.
Umie F.M. Haziz Rosenani A. Haque Shun-Ze Zhan Hassan H. Abdallah Mohd R. Razali 《应用有机金属化学》2020,34(10):e5818
The synthesis and characterizations for a series of dinuclear gold (I)-di-NHC complexes, 1–8 through the trans-metalation method of their respective silver (I)-di-NHC complexes, i–viii are reported (where NHC = N-heterocyclic carbene). The successful complexation of a series of unusual non-symmetrical and symmetrical di-NHC ligands, 3,3'-(ethane-1,2-diyl)-1-alkylbenzimidazolium-1'-butylbenzimidazolium (with alkyl = methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, benzyl) with the gold (I) ions are suggested by elemental analysis, Fourier transform-infrared, 1H- and 13C-NMR data. The 13C-NMR spectra of 1–8 show a singlet sharp peak in the range of 190.00–192.00 ppm, indicating the presence of a carbene carbon that bonded to the gold (I) ion. From single crystal X-ray diffraction data, the structure of complex 6 with the formula of [di-NHC-Au (I)]2·2PF6 is obtained [where NHC = 3,3'-(ethane-1,2-diyl)-1-hexylbenzimidazolium-1'-butylbenzimidazolium]. The photophysical study in solid state of 6 displays an intense photoluminescence with a strong emission maxima, λem = 480 nm, upon excitation at 340 nm at room temperature. Interestingly, the emission maximum at 77 K shows a structural character with a strong peak at 410 nm, a medium at 433 nm and a weak at 387 nm, accompanied by a tail band to about 500 nm. 相似文献
2.
《Tetrahedron letters》2019,60(24):1582-1586
Rh(II)-catalyzed decomposition of certain cyclic α-diazocarbonyl compounds in the presence of cyclic ethers has been shown to give bicyclic ring expansion products. These are thought to arise from a [1,4]-alkyl shift toward the carbonyl oxygen atom and are in contrast with the recently observed spirocyclic products of a Stevens-type [1,2]-alkyl shift within the postulated oxonium ylide intermediate. Quantum chemical calculations performed at the B3LYP/6-31G* level of theory showed that the former reaction pathway (toward fused bicycles) is kinetically preferred. 相似文献
3.
Junhua Chen 《Journal of organometallic chemistry》2006,691(3):470-474
Four novel hexadentate imidazolium salts were synthesized from hexakis(bromomethyl)benzene and 1-substituted imidazole. The arylation of aldehydes with arylboronic acids was effected conveniently and in high yields by a catalyst system generated in situ from these hexadentate imidazolium salts, [Rh(COD)Cl]2 and a base. 相似文献
4.
Adriana Tudose 《Tetrahedron letters》2006,47(48):8529-8533
Simple catalysts formed in situ from palladium acetate and a variety of imidazolium and imidazolinium carboxylates and dithiocarboxylates have been screened in the coupling of aryl halides with trans-2-phenylvinylboronic acid. Imidazol(in)ium carboxylates show an excellent activity, which compares to that displayed by the parent imidazol(in)ium chlorides, whereas imidazol(in)ium dithiocarboxylates are poorly efficient. Interestingly, the base employed exerts a profound influence on the trans/cis stereochemistry of the coupling product. 相似文献
5.
《Chemistry (Weinheim an der Bergstrasse, Germany)》2006,12(1):303-313
The reaction of electron‐deficient alkenes with alkoxyalkynyl Fischer carbene complexes (FCCs) represents a straightforward route to a new type of captodative (donor–acceptor) alkynylcyclopropanes, which have been prepared in moderate to high yields and in a diastereoselective manner. Some studies regarding the employment of additives to facilitate the recovery of the metal moiety after the reaction are also described. Finally, the first example of a cyclopropanation reaction through employing Fischer carbene complexes under microwave irradiation is presented; this method proved to be an advantageous alternative to the thermal reaction. 相似文献
6.
New, sterically demanding 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (2) as NHC precursors have been synthesized and characterized. These salts, in combination with palladium acetate, provided active catalysts for the cross-coupling of aryl chlorides and bromides under mild conditions. The catalytic system was applied to the Heck, Suzuki and benzaldehyde (Kumada) coupling reactions. Catalyst activity was found to be influenced by the presence of a methoxy group on the ring of the p-position of benzyl substituent of the ligand precursor. 相似文献
7.
Rüdiger Beckhaus 《Angewandte Chemie (International ed. in English)》1997,36(7):686-713
The relation of thermodynamic stability and kinetic lability of σ-organometallic compounds of transition metals, together with an improved understanding of the subtle interactions between central metal, ligands, and substrates, has increased the chemist's ability to plan organometallic syntheses. This article presents new results on intermediary and isolable synthetic building blocks incorporating metal–ligand multiple bonds of electron-deficient transition metals; the main emphasis will be placed on compounds with titanium–carbon double bonds. This particular class of compounds is mainly generated by H-transfer reactions starting from readily accessible alkyl and alkenyl derivatives. The preparative use of [L2Ti(CHR2)R′] derivatives as sources for [L2Ti?CR2] intermediates will be discussed, as well as the nature of these intermediates. Application of the same approach to vinyltitanium compounds [L2Ti(CH?CH2)R] opens up an access to a short-lived metallaallene derivative [L2Ti?C?CH2] of an electron-deficient transition metal. The reactivity of these synthetic building blocks is mainly characterized by the nucleophilic properties of the α-C atoms as well as by the spatial orientation of the π-bonding planes. Numerous cycloaddition products with unsaturated substrates could be isolated and characterized for the first time by using [L2Ti?C?CH2] intermediates. Hence it is possible to compare the properties of a multitude of metallacyclic ring systems with those obtained from “Tebbe–Grubbs chemistry”, and in this context, the dependence of the properties of metallacyclic four-membered rings on the substitution pattern is discussed. This class of compounds includes the metallaoxetanes, which have been obtained for the first time by the cycloaddition of the [CpTi?C?CH2] intermediate with cumulenes and metal carbonyls. The differing cycloreversion behavior of these metallaoxetanes enables the differentiation of species exhibiting classical and nonclassical reactivity. The number and position of the exocyclic double bonds are the determining factors of the reactivity of the formed metallacycles. The discussion of the products obtained from titanium methylene and vinylidene building blocks is an up-to-date report on the formation and applications of carbene complexes and carbene intermediates of group 4 metals. 相似文献
8.
Jingya Li 《Journal of organometallic chemistry》2007,692(17):3732-3742
A novel air- and moisture-stable carbene adduct of cyclopalladated ferrocenylimine has been synthesized and characterized. The structure of this compound was determined by X-ray crystal structure analysis. This adduct has been applied as an efficient catalyst for the amination of aryl chlorides. 相似文献
9.
A large‐scale synthetic route to a variety of phosphaformamidines and phosphaformamidinates, a type of derivative that was not accessible by the methods previously known for preparing phosphaamidines and phosphaamidinates, is reported. Thermally stable ethyl N‐arylformimidates 1 (ArN?CH(OEt), Ar=2,4,6‐(Me)3Ph or 2,6‐(iPr)2Ph) readily reacted with lithium dialkyl‐ and diarylphosphanides to afford the corresponding N‐aryl phosphaformamidines in 80 and 60 % yield, respectively, whereas with lithium (aryl)(silyl)phosphanide, the N‐aryl‐N‐silylphosphaformamidine (60 % yield) was obtained. Addition of primary lithium arylphosphanides to 1 followed by addition of a stoichiometric amount of nBuLi gave rise to the respective phosphaformamidinates (70–88 % yield). Methanolysis of the products afforded the N‐aryl‐N‐hydrogenophosphaformamidines (90–95 % yield). The solid‐state structure of one of the phosphaformamidinates is also presented. 相似文献
10.
Benchmarking of ruthenium initiators for the ROMP of a norbornenedicarboxylic acid ester 总被引:1,自引:0,他引:1
Sandra Demel Wolfgang Schoefberger Christian Slugovc Franz Stelzer 《Journal of molecular catalysis. A, Chemical》2003,200(1-2):11-19
The kinetic study of ring-opening metathesis polymerization (ROMP) of a diester functionalised norbornene derivative, (±)-exo,endo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid diethyl ester, with a series of ruthenium benzylidene complexes revealed the applicability of these initiators for well defined polymerization reactions. Values for the rate of initiation as well as the rate of propagation of the initiators were determined and correlated to the molecular weight and polydispersity of the isolated polymers. As the only initiator providing an entry to virtually monodisperse polymers the classical “first generation Grubbs-catalyst” was identified, while N-heterocyclic carbene based initiators polymerized with a rate of propagation much higher than the rate of initiation yielding polymers with a broader molecular weight distribution. 相似文献