Search results for "Protonation"
showing 10 items of 583 documents
Designing dicyanamide bridged 1D molecular architecture from a mononuclear copper(II) Schiff base precursor: Syntheses, structural variations and mag…
2009
International audience; A new tridentate N2O donor Schiff base ligand [(C6H5C(OH)CHC(CH3)NCH2C5H4N)LH] was obtained by 1:1 condensation of benzoylacetone with 2-picolylamine and has been used to synthesise a mononuclear [CuLCl] (1) and an end-to-end dicyanamide bridged polynuclear {[Cu2(μ-L)2(μ2-1,5-(CN)2N)]ClO4}n (2) copper(II) complexes. The ligand, 1 and 2 were clearly characterised by elemental analysis, FT-IR, 1H NMR, UV–Vis spectral studies, electrochemical studies and in addition single crystal X-ray diffraction studies were performed for 1 and 2. The Schiff base ligand [LH] shows a significant variation in its coordination behaviour with copper(II) ion in absence and in presence of …
Two Polymeric Compounds Built from Mononuclear and Tetrameric Squarate−Copper(II) Complexes by Deprotonation of 3,3-Bis(2-imidazolyl)propionic Acid (…
2001
Two polynuclear copper(II)−squarate compounds of formulas [Cu(HBIP)(BIP)](C4O4)1/2·2H2O (1) and [{Cu(BIP)(OH2)}4(μ-C4O4)](ClO4)2·4H2O (2) (HBIP = 3,3-bis(2-imidazolyl)propionic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Both compounds crystallize in the triclinic system, space group P1, with a =7.947(1) A, b =12.327(4) A, c = 13.150(3) A, α = 113.91(2)°, β = 99.85(2)°, γ = 90.02(2)° for compound 1 and a = 8.010(1) A, b = 13.073(1) A, c = 14.561(1) A, α = 72.13(1)°, β = 80.14(1)°, γ = 84.02(1)° for compound 2. The structure of compound 1 can be viewed as made up of [Cu(HBIP)(BIP)] units linked together by the BIP carboxylate groups to form a one-dimens…
Coordinative versatility of the carbonic anhydrase inhibitor benzolamide in zinc and copper model compounds
1999
New benzolamide (H 2 bz, 5-phenylsulfonamide-1,3,4-thiadiazole-2-sulfonamide) zinc(II) and copper(II) complexes with tris(2-benzimidazolyl-methylamine) (L) and ammonia are reported. The crystal structures of the Zn(II) complexes were determined. The [Zn(Hbz)L]ClO 4 · H 2 O compound crystallizes in the triclinic space group with a =11.006(1), b =14.777(2), c =14.918(2) A, α =114.30(1), β =98.90(1), γ =107.36(1)° and Z =2. In this compound the Zn(II) has a distorted trigonal bipyramidal geometry. The {[Zn 2 (bz) 2 (NH 3 ) 4 ] · 2H 2 O} ∞ crystallizes in the monoclinic space group C 2/ c with a =23.530(3), b =10.4124(11), c =15.428(2) A, β =110.591(9)° and Z =4. The metal centre is in a distor…
A Co(III) complex of carbonic anhydrase inhibitor methazolamide and the amino-imino ‘aib’ ligand formed by reaction of acetone and ammonia
1993
Abstract Reaction of Co(NO 3 ) 2 ·6H 2 O with methazolamide {[ N -(3-methyl-5-sulfamoyl-1,3,4-thiadiazol-2(3 H )-ylidene)acetamide] (Hmacm)} and ammonia in acetone to produce [Co(methazolamidate)(2-methyl-2-amino-4-iminopentane) 2 (NH 3 )](NO 3 ) 2 ·2H 2 O is described. The ligand 2-methyl-2-amino-4-iminopentane (aib) is the product obtained from the condensation of two ammonia and two acetone molecules. The complex crystallizes in the monoclinic space group P 2 1 / c with a =16.713(5), b =9.180(1), c =20.273(1) A, β=97.44(4)° for Z =4. The R value is 0.081 for 2150 significant reflections. The Co(III) ion exhibits a nearly regular octahedral arrangement with the CoN bond distances in the …
ChemInform Abstract: Microwave-Assisted Synthesis of Polysubstituted 4-Quinolones from Deprotonated α-Aminonitriles.
2011
The α-alkylations of deprotonated Strecker products such as (I) or (V) give a series of intermediates such as (III), (VI), or (X), which undergo microwave-assisted HCN and EtOH eliminations leading to the title quinolones (IV), (VII)/(VIII), or (XI).
One-Pot Synthesis of Trisubstituted 1,2-Amino Alcohols from Deprotonated α-Amino Nitriles
2008
A short synthesis of N,1,2-trisubstituted vicinal amino alcohols by 1,2-addition of deprotonated N-monosubstituted α-amino nitriles to aldehydes and subsequent one-pot reduction of the intermediates with borane–THF is described. This procedure leads to the predominant formation of the anti-configured products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
[1,2,3]Triazolo[1,5-a]pyridines. A theoretical (DFT) study of the ring-chain isomerization
2008
The ring opening isomerization of [1,2,3]triazolo[1,5-a]pyridines to the corresponding 2-pyridyl derivatives has been studied by means of DFT calculations at the B3LYP/6-31+G(d,p) computational level. The effect of the substitution as well as those of protonation, deprotonation, and lithiation on different positions has been studied. The electronic characteristics of the optimized structures have been analyzed by means of the Atoms In Molecules (AIM), Electron Localization Function (ELF), Molecular Electrostatic Potential (MEP), and Natural Bond Orbital (NBO) methodologies. © 2008 Elsevier Ltd. All rights reserved.
On the structure of 3-acetylamino-5-methyl-1,2,4-oxadiazole and on the fully degenerate rearrangements (FDR) of its anion: a stimulating comparison b…
2009
An accurate crystal structure determination has provided evidence for a planar conformation for 3-acetylamino-5-methyl-1,2,4-oxadiazole (5), in agreement with quantum-mechanical calculations in the gas phase. In the crystal, a series of strong intermolecular N7H7….O9 hydrogen bonds link the amido groups of different molecules, causing the formation of infinite parallel ordered chains. The effect of the DMSO solvent on the energy and charge distribution of compound 5 and on its relevant 5− anion, involved in a fully degenerate rearrangement (FDR), has been deepened by quantum-mechanical DFT calculations. The calculated energy barrier for the FDR increases in going from in vacuo to DMSO, in a…
2.14 Selected Diastereoselective Reactions: Enolate Alkylation
2012
This chapter discusses processes in which enolates are subjected to reaction with alkylating reagents. In all the processes examined here, at least one of the two reaction components is chiral and the reaction gives rise to one or more diastereomeric compounds. In most cases, the enolate is generated through deprotonation of the corresponding carbonyl precursor with a suitable base, but in several cases, the enolate is generated differently, for example, through Michael addition of a nucleophile to a conjugated carbonyl compound. The various factors that have been found to influence the stereochemical outcome of the alkylation reaction in a measurable way are also discussed. The material ha…
Synthesis of 1,2-Disubstituted Indoles from α-Aminonitriles and 2-Halobenzyl Halides
2016
The α-alkylation of deprotonated Strecker products derived from primary amines and aromatic aldehydes with 2-halobenzyl halides furnishes intermediates that can be cyclized to 1,2-disubstituted indoles in moderate to high yields (up to 94% over two steps) by microwave-assisted copper- or palladium-catalyzed intramolecular cross-coupling.