Search results for "SUBSTITUTION"
showing 10 items of 536 documents
Synthesis of Functionalized Indoles with a Trifluoromethy-Substituted Stereogenic Tertiary Carbon Atom Through an Enantioselective Friedel-Crafts Alk…
2010
[EN] Chiral complexes of BINOL-based ligands with zirconium tert-butoxide catalyze the Friedel-Crafts alkylation reaction of indoles with beta-trifluoromethyl-alpha,beta-unsaturated ketones to give functionalized indoles with an asymmetric tertiary carbon center attached to a trifluoromethyl group. The reaction can be applied to a large number of substituted alpha-trifluoromethyl enones and substituted indoles. The expected products were obtained with good yields and ees of up to 99%.
6-Thiopurine complexes of organotin(IV) moieties. Synthesis and structural characterization by infrared and Mössbauer spectroscopy
1982
Abstract The novel complexes Me3Sn(6-TP−1) and Bun2Sn(6-TP−1)2, where 6-TP−1 is the mono-anion of 6-thiopurine, have been synthesized. The sites of stannylation of 6-TP have been inferred from the known directions of electrophilic substitution reactions of 6-TP itself. The compounds have been characterized by infrared and Mossbauer spectroscopy. A solid state polymeric structure has been proposed for Me3Sn(6-TP−1), where planar SnC3 skeletons are bridged by 6-TP−1 (thione tautomer) axially bound to Sn through N(3) and N(1) atoms. For Bun2Sn(6-TP−1)2, a molecular structure has been advanced, with the ‘aromatic’ ligand anions chelating Sn by S-N(7) atoms.
I.R. Experimental studies of dynamical aspects of water structure: Effects of HD substitution and of small solutes
1980
Abstract Results on i.r. absorption spectra of H2O, D2O and electrolytic solutions and their thermal modifications are presented. From the data, some parameters can be obtained which are suitable for a description of dynamical aspects of water structure. Solute induced changes of these parameters provide a quantitative, although phenomenologic description of the water-solute interaction.
K2MIII2(MVIO4)(PO4)2 (MIII = Fe, Sc; MVI = Mo, W), Novel Members of the Lagbeinite-Related Family: Synthesis, Structure, and Magnetic Properties
2012
The possibility of PO(4)(3-) for MoO(4)(2-) partial substitution in the langbeinite framework has been studied by exploration of the K-Fe(Sc)-Mo(W)-P-O systems using the high-temperature solution method. It was shown that 1/3PO(4)(3-) for MoO(4)(2-) substitution leads to formation of three novel compounds K(2)Fe(MoO(4))(PO(4))(2), K(2)Sc(MoO(4))(PO(4))(2), and K(2)Sc(WO(4))(PO(4))(2) with slightly increased lattice parameters and significant distortion of the anion tetrahedra without structure changes. In contrast, the antiferromagnetic structure is modified by substitution in the low-temperature region. The structural peculiarities are discussed in light of bond-valence sums calculations.
Der austausch des cyclopentadienylliganden im methylcyclopentadienylmangan(I)tricarbonyl. Untersuchungen zur konkurrierenden komplexbildung mit methy…
1981
Abstract Exchange of the cyclopentadienyl ligand in methylcyclopentadienylmanganese(I) tricarbonyl with methyl-substituted benzenes is catalysed by AlCl 3 + HCl and leads to the cations [arene-Mn(CO) 3 ] + . The methylbenzenes isomerize and disproportionate during the reaction. The distribution of the arenes between the solution and the complex ions has been determined. The different complexing abilities of the arenes lead to the proposal of an associative mechanism for the ligand exchange.
Enhancing Performance of a Bis(arylimino)pyridine‐Iron Precatalyst for Ethylene Polymerization by Substitution with a 2,4‐Bis(4,4′‐dimethoxybenzhydry…
2021
A series of unsymmetrical 2-(2,4-bis(bis(4-methoxyphenyl)methyl)-6-MeC6H2N)-6-(1-(arylimino)ethyl)pyridine-iron halides has been synthesized and characterized. The molecular structure of two representative species was determined by the single-crystal X-ray diffraction. Activated with either MAO or MMAO, the precatalysts displayed high activity, reaching 2.19×107 g PE (mol Fe)−1 h−1 at 60 °C in ethylene polymerization. The microstructural analysis of the polymers obtained indicates highly linear polyethylene containing a vinyl chain end.
Effect of Peripheral Substitution and Extended Conjugation on the Redox Potentials of Nickel Porphycenes
1996
Eight different nickel porphycenes bearing substituents on the pyrrole β and/or ethylenic carbon positions of the macrocycle were investigated as to their redox properties in benzonitrile containin...
The nature of the chlorination reaction in [1-C6H5-1-CB9H9]- boron clusters.
2010
Preferential chlorination sites resulting from sequential radical substitution reactions in carborane anions have been studied combining experimental and computational methods. Results have been obtained experimentally by mixing the substrate with incremental ratios of N-chlorosuccinimide and analysing the resulting samples by negative MALDI-TOF-MS. The theoretical results have been obtained calculating the 2a-NPA charges on the starting material and computing the most energetically favourable reaction pathway.
Preparation, Properties, and Reactivity of (Aminoferrocenyl)(ferrocenyl)carbene(pentacarbonyl)chromium(0) as Bulky Isolobal Trimetallo-amide
2015
Nucleophilic substitution of the ethoxy substituent in the Fischer carbene complex (ethoxy)(ferrocenyl)carbene(pentacarbonyl)chromium(0) (1) by ferrocenyl amide [Fc-NH]– [2-H]– gives the hetero trimetallic complex (aminoferrocenyl)(ferrocenyl)carbene (pentacarbonyl)chromium(0) (3). As the Cr(CO)5 fragment is isolobal to oxygen or sulfur 3 can be viewed as an isolobal metallo analogue to diferrocenylamide (Fc)(FcNH)C=O (4) and diferrocenylthioamide (Fc)(FcNH)C=S (5). The impact of the formal replacement of O/S by Cr(CO)5 in 3 is studied with respect to steric and electronic consequences as well as reactivity by spectroscopic, diffraction, electrochemical and theoretical methods.
Reaction of dirhodium and diruthenium paddlewheel tetraacetate complexes with nucleophilic protein sites: A computational study
2022
Abstract The biomolecular affinity of three paddlewheel dinuclear complexes Rh2(µ-O2CCH3)4(H2O)2, Ru2(µ-O2CCH3)4(H2O)Cl, [Ru2(µ-O2CCH3)4(H2O)2]+ for the binding at cancer-specific protein targets was determined by means of DFT approaches. Thermodynamics of axial ligand substitution reaction by models of suitable protein sites was investigated in order to assess the binding selectivity displayed by the paddlewheel complexes. Both Rh2(µ-O2CCH3)4(H2O)2 and Ru2(µ-O2CCH3)4(H2O)Cl resulted to react favorably with most of the examined models of the protein side chains, with higher exergodicity demonstrated in the reaction of Arg, Cys, His, Lys, Sec, thus showing a limited selectivity. On the other…