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61.
The coordination of silver cation to diphosphene Mes*P=PMes* ( 1 , Mes* = tBu3C6H2) was investigated in detail. The reaction of 1 with Ag[Al(ORF)4] (ORF = OC(CF3)3) in the ratios of 2 : 1, 3 : 2 and 1 : 2 led to the formation of the first cationic silver linked diphosphene complexes 2 — 4 . Complexes 2 and 3 contain two and three diphosphene molecules linked by the linear Ag(I) cation, respectively, and they feature unusual zig‐zag topologies. Complex 4 is a dinuclear silver complex, and each Ag(I) center features a tetrahedral geometry, coordinated by one phosphorus atom of diphosphene 1 and three chloro atoms of two CH2Cl2 molecules. 相似文献
62.
CuO/活性炭和Fe2O3/活性炭催化还原NO 总被引:4,自引:0,他引:4
CuO/活性炭和Fe_2O_3/活性炭催化还原NO高志明,赵震,杨向光,吴越(中国科学院长春应用化学研究所长春130022)关键词活性炭,还原,NO,氧化铜,氧化铁目前,对固定源的NO处理是采用V2O5/TiO2作催化剂,NH3作还原剂的选择催化还原方... 相似文献
63.
64.
Different from Rh(II) catalysts, X-H (X = O, S, N) insertion of methyl styryldiazoacetate catalyzed by Lewis acids including Cu(I), Cu(II) and Ag(I) complexes occurred at γ-position preferably. Only (E)-isomer was observed in the reactions. This method provides an alternative for the synthesis of γ-hydroxyl or γ-amino acid derivatives. 相似文献
65.
A nickel catalyst was nodeled with ligand L^2,[NH=CH-CH=CH-0]^-,which should have potential use as a syndiotactic plyolefin catalyst,and the reaction mechanism was studied by theoretical calculations using the density functinal method at the B3LYP/LANL2MB level.The mechanism involves the formation of the intermediate [NiL^2Me]^ ,in which the metal occupies a T-shaped geometry.This intermediate has two possible structures with the methyl group trans either to the oxygen or to the nitrogen atom of L^2.The results show that both structures can lead to the desired product via similar reaction paths,A and B.Thus,the polymerization could be considered as taking place either with the alkyl group occupying the position trans to the Ni-0 or trans to the Ni-N bond in the catalyst.The polymerization process thus favors the catalysis of syndiotactic polyolefins.The syndiotactic synthesis effects could also be enhanced by varations in the ligand substituents.From energy considerations,we can conclude that it is more favorable for the methyl ttrans-O position to form a complex than to occupy the trans-N position.From bond length considerations,it is also more favoured for ethene to occupy the trans-O position than to occupy the trans-N position. 相似文献
66.
photoelectron-photoion coincidence spectroscopy and density functional theory calculations have been used to investigate the dissociation kinetics of the benzene chromium tricarbonyl ion, BzCr(CO)3+ (Bz = C6H6). The dissociation of the BzCr(CO)3+ ion proceeds by the sequential loss of three CO and benzene ligands. The first and third CO and the benzene loss reactions were associated with metastable precursor ions (lifetimes in the microsecond range). By simulating the resulting asymmetric time-of-flight peak shapes and breakdown diagram, the 0 K appearance energies of the four product ions were determined to be 8.33 +/- 0.05, 8.93 +/- 0.05, 9.97 +/- 0.06, and 11.71 +/- 0.06 eV, respectively. Combined with the ionization energy of BzCr(CO)3, 7.30 +/- 0.05 eV, the three successive Cr-CO bond energies in the BzCr(CO)3+ were found to alternate, with values of 1.03 +/- 0.05, 0.60 +/- 0.05, and 1.04 +/- 0.05 eV, respectively, and the Bz-Cr bond energy in BzCr+ is 1.74 +/- 0.05 eV, a trend confirmed by the density functional theory (DFT) calculations. Using the heats of formation of the fully dissociated products, C6H6, Cr+, and CO, the 298 K heats of formation the ionic BzCr(CO)n+ (n = 03) species were determined. By scaling the DFT calculated bond energies for the neutral molecules, the heats of formation of the neutral BzCr(CO)n (n = 03) were also obtained. 相似文献
67.
Six new 4″-benzyloxyimino-4″-deoxyavermectin Bla derivatives were synthesized from avermectin Bla by the selective protection of C-5-hydroxy group,oxidation of C-4″-hydroxy group,and deprotection followed by reaction with O-substituted hydroxylamine hydrochlorides.Their structures were confirmed by IR,~1H NMR,~(13)C NMR and MS.Insecticidal activities of the derivatives against Phopalosiphum pseudobrassicae,Spodoptera exigua and Pluteua xylosteua were evaluated. 相似文献
68.
In this report, we describe a novel method for preparing amorphous carbon nanotubes (ACNT) from silver nanowires using a carbon replica technique. ACNT size and shape are determined by the template silver nanowire. Interspaces between carbon grains present in the ACNT wall cause the wall to act as a permeable membrane through which reactants pass freely. Simple chemical modifications can be used to modify the diameter of the silver filaments within. We anticipate that this method will prove useful in preparing a wide variety of nanometer-sized filaments, perhaps with the replica itself able to serve as a template in casting nanomaterials of assorted shapes. Copyright 2000 Academic Press. 相似文献
69.
70.
Solid-state nanopore in analytical chemistry has developed rapidly in the 1990s and it is proved to be a versatile new tool for bioanalytical chemistry. This review focuses on the analysis of ions and small molecules with nanopores including nanopipettes, polymer film nanopores, Si3N4 nanopores, graphene nanopores, MoS2 nanopores and MOFs. 相似文献