Crystal and Molecular Structures of N-benzyl-C-(2-pyridyl) nitrone and its ZnBr2 Complex. A Study of Their Reactivity (original) (raw)
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Inorganica Chimica Acta, 2001
The X-ray analysis of Co(II), Ni(II) and Zn(II) dichloro complexes containing 2-(2-pyridyl)-4,4,5,5-tetramethylimidazolin-1-oxyl 3-oxide (NIT2py) demonstrated that the Co(II) complex containing two dichloromethane solvate molecules, [CoCl 2 (NIT2py) 2 ]•2CH 2 Cl 2 (1), crystallizes in a space group P2 1 /c isomorphous to the corresponding Mn(II), Ni(II) (2) and Cu(II) complexes, and that the molecular structure of the complex having C i symmetry in 1 is isostructural to the above Mn(II), Ni(II) and Cu(II) complexes. A new Ni(II) complex having only one dichloromethane solvate molecule, [NiCl 2 (NIT2py) 2 ]•CH 2 Cl 2 (2%), could be crystallized from a mixture of dichloromethane, methanol and n-heptane. The (OC-6-12)-[trans(Cl)-trans(py)] geometrical structure of the Ni(II) complex in 2% is identical to that in 2, but the puckered six-membered chelate rings formed via pyridyl-N and nitroxide-O atoms of NIT2py take the different conformations; i.e. the molecular symmetry is C 2 (racemate) with the l, l or d, d conformations in 2% and C i (meso) with the d, l conformations in 2. In the case of Zn(II), a reaction of ZnCl 2 with NIT2py afforded purple crystals consisting of octahedral bis(NIT2py) and tetrahedral mono(NIT2py) complexes with hydration: [ZnCl 2 (NIT2py) 2 ]•2[ZnCl 2 (NIT2py)]•2/3H 2 O (3). The geometrical structure of the octahedral Zn(II) complex in 3 was found to be (OC-6-22)-[cis(Cl)-trans(py)].
Crystal Structure and Chemical Properties of Ni(II)–Zn(II) Hetero-Dinuclear Complex
Journal of Supramolecular Chemistry, 2002
A dinuclear Ni(II)-Zn(II) complex of 2-bis-(aminoethyl)-aminomethylphenol (L) was prepared by mixing the homodinuclear complexes of Ni(II) and Zn(II). The mixed hetero-dinuclear complex was characterized by X-ray analysis. Crystal data for the compound [NiZn(H -1 L) 2 (H 2 O) 2 ][ClO 4 ] 2 revealed that it is monoclinic; space group P2 1 /n with a=20.137(2) Å , b=9.480(1) Å , c=15.934(1) Å , b=100.45(1) , V=2991.3(5) Å 3 , Z=4, R=0.094. #
Zn ( II ) COMPLEX OF 2 , 6-BIS ( 4-NITROBENZAMIDO ) PYRIDINE : SYNTHESIS AND CHARACTERIZATION
2016
Zn(II) complex containing pyridine and benzamide units was prepared via two step reactions. Nucleophilic chloro-displacement reaction of 2,6-diaminopyridine with 4-nitrobenzoyl chloride in the presence of propylene oxide afforded 2,6-bis(4nitrobenzamido)pyridine (BNBP) as a ligand. This step reaction using Taremi method with some modifications and continued by refluxing method with ZnCl2 to produced complex compound. Characterization of compound by 1H-NMR indicated that there are 5 types of protons, with each shift (δ) 10.893 s, (δ) 8.318 d, (δ) 8.174 d (δ) 7.896 t, and (δ) d 7.870 ppm. 13C NMR spectra showed 8 types of carbons on each region shifts (δ) 160.135, (δ) 145.766, (δ) 144.917, (δ) 135.840, (δ) 135.421, (δ) 125.066, (δ) 119.088 and (δ) 107.466 ppm. Characterization of Zn(II) complex using the FTIR showed that the complex bond is formed from the free electron pair donated by N-H amide of 2,6-bis (4-nitrobenzamido) pyridine. UV-Vis spectra showed a maximum wavelength 320 nm ...
Preferred geometry of unusual nitrones. A facile E-Z isomerization of a C-alkoxynitrone
The Journal of Organic Chemistry, 1991
A detailed structural study was carried out on C-methoxy-C-aryl-N-tert-butylnitronee (l), members of a relatively new class of compounds (acyclic imidate N-oxides). By ' H NMFt chemical shifta it was shown that 1 exist exclusively as the E isomers in DCCIB and the 2 isomers in acetone-& NOE difference spectra confirm these assignments and indicate a preferred conformation in which 0-methyl and C-phenyl are more syn periplanar than anti in both cases. Configurations and conformations were similarly determined for C-phenyl-N-tert-butylnitrone (PBN), as well as several nitrone salts. Rates of E to 2 isomerization of the phenyl, p-methoxyphenyl, and p-nitrophenyl derivatives of 1 were measured in acetone from 266 to 280 K giving AH* values of 14.1,16.9, and 14.2 kcal/mol and AS* values of-24.3,-14.5, and-25.5 eu, respectively. The unusually low values of AH* are interpreted in terms of ground-state destabilization due to steric repulsions that are relieved in going to the transition state by rotation about the C-N bond. The large negative AS* values suggest solvent reorganization to stabilize the charge-separated character of the transition state. Geometry-optimized MNDO calculations are in agreement with conformation results from NOE experiments and predict a large dipole moment difference between E and 2 isomers.
2010
The first dinuclear nickel complex with an azapurine derivative is reported. The crystal structure consists of discrete [Ni 2 (dmax) 3 (H 2 O) 2 (dben) 2 ] + cations, the charge of which is balanced by interstitial dmax anions, where dmax = 4,6-dimethyl-1,2,3-triazolo[4,5-d]pyrimidin-5,7-dionato and dben = N,N′-dibenzylethylenediamine. The nickel centres are bridged by three heterocyclic anions through two nitrogen atoms of their triazole ring. The presence of the bulky auxiliary ligand clearly favours the bridging behaviour of the main ligand, probably by hindering the formation of H-bonds with dmax N atoms as acceptors. H-bonding is however, the main packing interaction, with eight different well defined intermolecular H-bonds that build a 3-D network that is analysed.
1,3-Dipolar cycloadditions of new 2,5-bifunctionalized five-membered cyclic nitrones
Tetrahedron, 2012
A new family of five-membered cyclic nitrones bearing functional groups at positions 2 and 5 were tested in 1,3-cycloadditions with various dipolarophiles. These reactions gave the corresponding cycloadducts as single diastereomers in high yields. The reaction scope was examined, 23 compounds were isolated and fully characterized. The comparison of the reactivity was carried out by a study of reaction conversions while different nitrones or dipolarophiles were used. In addition, the exceptional reactivity of nitrone bearing benzylamino group in position 2 was studied. The formation of the nitrone complex and evaluation of its reactivity in 1,3-DC is presented.
Journal of Materials Science and Nanotechnology, 2014
C 12 H 20 N 6 NiO 6 S 2 or NiL 2 (SCN) 2 ](NH 4) 2 .2H 2 O, where L is 2-hydroxy-pyridine-N-oxide, has been prepared and characterized using elemental analyses, IR, UV and visible spectrometry, magnetic moment measurements, thermal analyses and single crystal X-ray analyis. The results indicate that the complex reacts as a bidentate ligand and is bound to the metal ion via the two oxygen atoms of the ligand (HL). The activation energies, ∆E*, entropies ∆S*, enthalpies ∆H* and order of reactions have been derived from differential thermogravimetric (DTA) curves. Based on inhibition zone diameter measurements, the complex exhibited significant antibacterial activity against both Staphylococcus aureus and Escherichia coli. It also exhibited significant antifungal activity against Candida albicans, but no activity was found against Aspergillus flavus. The crystal structure of the Ni(II) complex [C 12 H 20 N 6 Ni O 6 S 2 ], Mr = 467.17, was determined from Cu Kα X-ray diffraction data, λ = 1.54178 Å, at 100 K using direct methods. The crystals are monoclinic, space group P2 1 /n with Z = 4 and a = 8.9893(2) Å, b = 17.6680(5) Å, c = 12.5665(3) Å, β = 108.609(1)°. In parallel with this study corresponding results were derived for the crystal structure determined independently from synchrotron X-ray diffraction data, λ = 0.61990 Å, at 100 K. The unit cell parameters derived in this experiment are a = 9.000(2) Å, b = 17.700(4) Å, c = 12.590(3) Å, β = 108.61(3)°. Both studies show 4 O and 2 N atoms coordinating Ni in a distorted octahedral arrangement. Each of the Ni 2-hydroxy-pyridinium-N-oxide moieties is highly planar and the S=C=N-Ni ligands are approximately linear. The crystal structure is characterised by a number of strong hydrogen bonds.