共查询到20条相似文献,搜索用时 15 毫秒
1.
Magnus R. Buchner 《Journal of organometallic chemistry》2008,693(26):3943-3946
The reaction of [IrCl(dmso)3] with trisphosphinomethylborato ligand Li(THF){PhB(CH2PiPr2)3} at room temperature results in intramolecular C-H activation of one of the iPr substituents affording two diastereomers of cyclometalated iridium(III) complex [Ir(H)(dmso){PhB(CH2PiPr2)2(CH2PiPrCHMeCH2)}] (1) in high yield in approximately equimolar ratio. NMR spectroscopic characterization indicates that only the diastereomers with the hydride ligand in cis position with respect to the metalacyclic phosphorous atom are formed as confirmed by single crystal X-ray diffraction. Facile ring opening with H2 at room temperature gives dihydride [Ir(H)2(dmso){PhB(CH2PiPr2)3}] (2). However, C-H activation of benzene was not observed. 相似文献
2.
概述了Ru催化的碳氢键的活化反应,包括C-H/烯烃,C-H/炔径和C-H/CO/烯烃 偶联反应,加氢酰化反应,硅化反应。 相似文献
3.
Margarita Crespo Jaume Granell Xavier Solans 《Journal of organometallic chemistry》2004,689(19):3088-3092
The reactions of compound [Pt(dba)2] with ligands RCHNCH2CH2NMe2 (1a-1f) in which R is a fluorinated aryl ring produced activation of C-F bonds when two fluorine atoms are present in the ortho positions of the aryl ring or activation of C-H bonds for ligands containing only one fluoro substituent in ortho. Both C-F and C-H bond activation are favoured by an increase of the degree of fluorination of the ring. Further reaction with lithium halides produced cyclometallated platinum (II) compounds [PtX(Me2NCH2CH2NCHR)] (X = Br, Cl) (2) containing a terdentate [C,N,N′] ligand. The obtained compounds were fully characterized including a structure determination for [PtCl{Me2NCH2CH2NCH(2,4,5-C6HF3)}] (2d′). 相似文献
4.
The C-S bond formation reactions of the transition metal sulfides with organic molecules are collected and reviewed to understand the reactivity of the sulfide ligands supported by the transition metals. As an example of the role of the sulfide, the C-H bond activation is focused and discussed. 相似文献
5.
A Pd (OAc)2-catalyzed direct arylation of benzoxazole C-H bonds has been achieved with iodobenzene diacetates as the arylation reagent in moderate to good yields. The procedure tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, and bromo groups. 相似文献
6.
Chi-Jeh Lin Wen-Shu Hwang Michael Y. Chiang 《Journal of organometallic chemistry》2001,640(1-2):85-92
When thienyl Schiff base 1, derived from 2-formylthiophene and hydrazine, reacted with Fe2(CO)9 in n-hexane, three major complexes were obtained: (1) a diironhexacarbonyl complex with two 2-thienylmethylideneamido bridging ligands 2, which resulted from the =N---N= bond cleavage of ligand 1; (2) a doubly cyclometalated di-μ-di-(η1:η2-thienyl; η1:η1(N))bis(hexacarbonyldiiron) complex (3); and (3) a cyclometalated (μ-η1:η2-thienyl; η1:η1(N))hexacarbonyldiiron complex (4). Molecular structures of compounds 1a, 1c, and 2a have been determined by single-crystal X-ray diffraction. 相似文献
7.
An intermolecular carbamoylation of ethers has been achieved via photoinduced functionalization of ethereal C-H bonds in the presence of benzophenone at ambient temperature. The carbamoyl group, a one-carbon unit with a high oxidation state, derived from pentafluorophenyl isocyanate (C6F5NCO) is chemoselectively introduced at the position geminal to the oxygen functionality in a single step. The present reaction system effectively activates the tertiary C-H bond at the sterically hindered site of fused bicyclic systems, and enables introduction of the carbamoyl group, which is then available for further synthetic elaborations. 相似文献
8.
Fernando Rascón 《Journal of organometallic chemistry》2011,696(25):4121-4131
Well-defined surface alkylidenes and alkylidynes can be compared to their molecular counterparts in structural features and formation pathways, but their reactivity towards alkanes is strikingly different. They catalyse the metathesis of alkanes and cross-metathesis of alkanes, whereas no single-component molecular system is known to do so. Herein, we study such reactivity in terms of structure-activity relationships, to further propose a comparison to the reactivity of well-defined group 4-6 supported hydrides, focused on the alkane metathesis and alkane hydrogenolysis processes. There, the formation of intermediates containing alkylidenes and alkylidynes nicely pinpoints their pre-eminence in the catalytic conversion of alkanes, always in agreement with the elementary steps of molecular organometallic chemistry. Finally, a number of relevant reactions where the formation of alkylidene/alkylidyne intermediates has been presumed are also presented. 相似文献
9.
In the review paper, we attempt to point out the importance of the directing group in the transition metal-catalyzed C-H bond activation/transformations, especially in the site-selectivity and reactivity. The employment of the directing groups in the type of reaction can enable a chemist to straightforwardly approach the desired molecular skeletons. Thus, understanding the role of the directing groups in the C-H bond activation/transformations would benefit chemists to design better auxiliary groups and develop more efficient and practical synthetic methodologies. We believe that the synthetic strategy based on the utility of the directing group to assist in the transition metal-catalyzed C-H bond activation/transformations will keep playing as a mainstream role in the research field. 相似文献
10.
11.
A theoretical investigation of the reaction mechanisms for C-H and C-C bond activation processes in the reaction of Ni with cycloalkanes C,,H2. (n = 3-7) is carried out. For the Ni + CnH2, (n = 3, 4) reactions, the major and minor reaction channels involve C-C and C-H bond activations, respectively, whereas Ni atom prefers the attacking of C-H bond over the C-C bond in CnH2n (n = 5=7). The results are in good agreement with the experimental study. In all cases, intermediates and transition states along the reaction paths of interest are characterized, It is found that both the C-H and C-C bond activation processes are proposed to proceed in a one-step manner via one transition state. The overall C-H and C-C bond activation processes are exothermic and involve low energy barriers, thus transition metal atom Ni is a good mediator for the activity of cycloalkanes CnH2n (n = 3 -7). 相似文献
12.
S. L. Litvinenko T. V. Bezbozhnaya V. V. Zamashchikov 《Theoretical and Experimental Chemistry》2007,43(6):396-398
The phenanthroline complex, Pt(phen)Cl2, catalyzes the coupling of aromatic hydrocarbons with p-iodonitrobenzene under phase transfer conditions using 50% aqueous
KOH and 18-crown-6. The yield of the asymmetric diaryl products is 10,000–12,000% relative to the catalyst. A mechanism was
proposed involving the oxidative addition of ArI to an Ar-PtII intermediate species with subsequent reductive elimination of the final product Ar-Ar′ from Ar-PtIV-Ar′.
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Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 6, pp. 364–366, November–December, 2007. 相似文献
13.
14.
Reaction of (Ph2P(o-C6H4)CHNCH2CH2)3N with 3 equiv. of Os3(CO)10(NCMe)2 at ambient temperature affords the triple cluster [Os3(CO)10Ph2P(o-C6H4)CHNCH2CH2]3N (1) through coordination of the phosphine and imine groups. Thermolysis of 1 in benzene leads to decarbonylation and C-H/C-N bond activation of the ligand to generate (μ-H)Os3(CO)8(μ3-Ph2P(o-C6H4)CHNCCH2) (2). The molecular structure of 2 has been determined by an X-ray diffraction study. 相似文献
15.
A simple and efficient Rh(III)-catalyzed C-H activation and tandem intramolecular cyclization for the synthesis of isocoumarins has been developed. The protocol uses easily available primary benzamides and cyclic 2-diazo-1,3-diketones as starting materials. This reaction proceeds via C-C and C-O bond formation in a single reaction vessel, and the corresponding isocoumarins were obtained in moderate to excellent yields (58%–97%). The well established protocol showed high functional group tolerance, which provided an efficient and alternative route to isocoumarin backbone. 相似文献
16.
The mechanism of cyclopalladation of azobenzene (L) with PdCl2 in N,N-dimethylformamide (dmf) was studied computationally, using DFT (B3LYP) methods supplemented with a continuum solvation model. Since the exact nature of the reacting complex is unknown, several candidates were considered. These were: (1) a mononuclear adduct with two ligand molecules, L-PdCl2-L, (2) a mononuclear adduct with one ligand and one solvent molecule, L-PdCl2-dmf, (3) a dinuclear adduct with a double chloride bridge, [L-PdCl-(μ-Cl)]2, and (4) a coordinatively unsaturated complex with an agostic interaction, L-PdCl2. The reaction profile initiating from L-PdCl2-dmf, which displays an agostic intermediate produced after displacement of the dmf molecule by the activating C-H bond, has the lowest barrier (20.4 kcal/mol in the step with the proton transfer to the O(dmf) atom). In all other reaction pathways, the proton migration is to a chlorine atom and is associated with remarkably high barriers. The results are related to previous experimental and other computational findings. While none of the reaction profiles includes explicit dissociation of the ligand, the proton transfer was found to occur only after the ligand is almost completely displaced from the coordinating shell. It was concluded that the transition state corresponds to 14-electron coordination of Pd and that ease of a ligand dissociation is an important, but not necessarily decisive, factor for cyclopalladation. 相似文献
17.
Leticia Naya Margarita López-Torres José M. Vila Nina Gómez-Blanco 《Journal of organometallic chemistry》2008,693(4):685-700
Reaction of Pd(AcO)2 with the Schiff base ligands 2-Br-4,5-(OCH2O)C6H2C(H)N(Cy) (a) and 4,5-(OCH2CH2)C6H3C(H)N(Cy) (b) leads to the cyclometallated compounds [Pd{2-Br-4,5-(OCH2O)C6HC(H)N(Cy)-C6,N}(μ-O2CMe)]2 (1a) and [Pd{4,5-(OCH2CH2)C6H2C(H)N(Cy)-C6,N}(μ-O2CMe)]2 (1b), respectively, via C-H activation. Treatment of a with Pd2(dba)3 gave [Pd{4,5-(OCH2O)C6H2C(H)N(Cy)-C2,N}(μ-Br)]2 (6a), via C-Br activation. The metathesis reaction of 1a and 1b with aqueous sodium chloride gave the corresponding cyclopalladated dimers with bridging chloride ligands, 2a and 2b, respectively. Treatment of the halogen-bridged compounds with tertiary tri- and diphosphines in the appropriate molar ratio gave the mono and dinuclear compounds 3a-5a, 7a-9a and 3b-5b. The structure of compounds 3a, 4a, 5a, 8a, 2b, 3b and 5b has been determined by X-ray diffraction analysis. 相似文献
18.
An efficient route to synthesize biologically interesting 8-aryl-1,2,3,4-tetrahydroisoquinoline has been developed. It involves the Pd-catalyzed direct arylation of 3,4-dihydroisoquinolones via C-H bond activation with aryl iodides to afford a variety of 8-arylated cross-coupling products, which are subsequently reduced to 8-aryl-1,2,3,4-tetrahydroisoquinolines in good to excellent yields. 相似文献
19.
A modified bidentate directing ligand derived from 2,1,3-benzoselenadiazole (BSeD) was designed and synthesized. It exhibited high regioselectivity in the catalytic activation of unactivated C(sp3)-H bonds with aryl iodides in the presence of palladium catalyst in yields up to 94%. 相似文献
20.
The C–H homolytic bond dissociation enthalpies (BDEs) of 27 heterocyclic compounds of small systems (less than 8 non-hydrogen atoms) were evaluated by the composite ab initio methods of G4 and CBS-Q. In addition, the C–H BDEs of an extended database including 60 heterocyclic compounds were assessed by 16 DFT functionals. The correlation between the theoretical and experimental values reveals that the BMK functional provided the lowest root mean square error (RMSE) of 10.2 kJ/mol, and the correlation coefficient (R2) was 0.955. The mean deviation (MD), mean absolute deviation (MAD) of BMK are 0.1 kJ/mol and 7.9 kJ/mol separately. Therefore, we utilized BMK to research C–H BDEs together with the substituent effects of five-membered and six-membered heterocyclic compounds including large systems. The nature of C–H BDE change pattern was analyzed by the natural bond orbital (NBO). 相似文献