Search results for "Anion"
showing 10 items of 488 documents
CCDC 751525: Experimental Crystal Structure Determination
2010
Related Article: R.T.Boere, T.Chivers, T.L.Roemmele, H.M.Tuononen|2009|Inorg.Chem.|48|7294|doi:10.1021/ic900742q
CCDC 2045404: Experimental Crystal Structure Determination
2021
Related Article: Emmelyne Cuza, Rachid Motei, Fatima Setifi, Abdeslem Bentama, Carlos J. Gómez-García, Smail Triki|2021|J.Appl.Phys.|129|145501|doi:10.1063/5.0046055
Tests against stationary and explosive alternatives in vector autoregressive models
2008
. The article proposes new tests for the number of unit roots in vector autoregressive models based on the eigenvalues of the companion matrix. Both stationary and explosive alternatives are considered. The limiting distributions of test statistics depend only on the number of unit roots. Size and power are investigated, and it is found that the new test against some stationary alternatives compares favourably with the widely used likelihood ratio test for the cointegrating rank. The powers are prominently higher against explosive than against stationary alternatives. Some empirical examples are provided to show how to use the new tests with real data.
Tests for real and complex unit roots in vector autoregressive models
2014
The article proposes new tests for the number of real and complex unit roots in vector autoregressive models. The tests are based on the eigenvalues of the sample companion matrix. The limiting distributions of the eigenvalues converging to the unit eigenvalues turn out to be of a non-standard form and expressible in terms of Brownian motions. The tests are defined such that the null distributions related to eigenvalues +/-1 are the same. The tests for the unit eigenvalues with nonzero imaginary part are defined independently of the angular frequency. When the tests are adjusted for deterministic terms, the null distributions usually change. Critical values are tabulated via simulations. Al…
Single chain magnet behaviour in an enantiopure chiral cobalt(II)–copper(II) one-dimensional compound
2010
The self-assembly of an enantiomerically pure, chiral dianionic oxamatocopper(II) complex with cobalt(II) ions leads to neutral oxamato-bridged heterobimetallic chains that combine chirality and slow magnetic relaxation, providing thus the first example of ‘‘chiral single chain magnets (CSCMs). Ruiz Garcia, Rafael, Rafael.Ruiz@uv.es ; Lloret Pastor, Francisco, Francisco.Lloret@uv.es
Multiscale Simulations of SARS-CoV-2 3CL Protease Inhibition with Aldehyde Derivatives. Role of Protein and Inhibitor Conformational Changes in the R…
2021
We here investigate the mechanism of SARS-CoV-2 3CL protease inhibition by one of the most promising families of inhibitors, those containing an aldehyde group as a warhead. These compounds are covalent inhibitors that inactivate the protease, forming a stable hemithioacetal complex. Inhibitor 11a is a potent inhibitor that has been already tested in vitro and in animals. Using a combination of classical and QM/MM simulations, we determined the binding mode of the inhibitor into the active site and the preferred rotameric state of the catalytic histidine. In the noncovalent complex, the aldehyde group is accommodated into the oxyanion hole formed by the NH main-chain groups of residues 143 …
A theoretical study of carbon-carbon bond formation by a Michael-type addition.
2012
A theoretical study of the Michael-type addition of 1,3-dicarbonyl compounds to α,β-unsaturated carbonyl compounds has been performed in the gas phase by means of the AM1 semiempirical method and by density functional theory (DFT) calculations within the B3LYP and M06-2X hybrid functionals. A molecular model has been selected to mimic the role of a base, which is traditionally used as a catalyst in Michael reactions, an acetate moiety to modulate its basicity, and point charges to imitate the stabilization of the negative charge developed in the substrate during the reaction when taking place in enzymatic environments. Results of the study of six different reactions obtained at the three di…
Synthesis of Macromolecular Substances by Addition Polymerization
2001
As already explained, polymerization reactions can proceed by various mechanisms and can be catalyzed by initiators of different kinds. For addition polymerization of single compounds, initiation of chains may occur via radical, cationic, anionic, or so-called coordinative-acting initiators, but some monomers will not polymerize by more than one mechanism. Both thermodynamic and kinetic factors can be important, depending on the structure of the monomer and its electronic and steric situation. The most important initiators are summarized in Table 3.1.
Planar-Chiral 1,1 '-Diboryl Metallocenes: Diastereoselective Synthesis from Boryl Cyclopentadienides and Spin Density Analysis of a Diborylcobaltocene
2017
International audience; The reaction of nonsubstituted alkali metal cyclopentadienides with haloboranes leads to similar to 90:10 mixtures of isomeric diene products that can be deprotonated to give simple boryl cyclopentadienides. We extended this transformation to the sterically hindered lithium tert-butylcyclopentadienide 1 using FBMe(s)2 (Mes = 2,4,6-trimethylphenyl) and ClBCy2 as electrophiles. The boryl group is selectively introduced in the remote position to minimize steric congestion. The new boryl dienes are obtained as mixtures of isomers, and subsequent deprotonation with MeLi or LiHMDS affords the lithium 1,3-disubstituted cyclopentadienides Sa,b in yields over 95%. Direct asse…
Triazolopyridines. 14. Substitution reactions of 7-amino[1,2,3]triazolo[1,5-a]pyridines.
1993
Abstract Reaction between 7-aminotriazolopyridines 1 or 2 and sulphuric acid gives hydroxyalkylpyridines 3 and 4 ; bromination gives brominated pyridine 5 or triazolopyridine 6. The anions from amines 1 or 2 are ambident, acylating on N but alkylating on N or on C6; in the latter case triazolylalkenylcyanides 16 – 20 or the 6,6-dialkylated derivative 19 are obtained. An X-ray diffraction study has confirmed structure 19.