Search results for "Proton"
showing 10 items of 5886 documents
"Table 14" of "Probing the quantum interference between singly and doubly resonant top-quark production in $pp$ collisions at $\sqrt{s}=13$ TeV with …
2019
The detector-level minimax-m(bl) distribution for events entering the Z+jets control region.
"Table 15" of "Probing the quantum interference between singly and doubly resonant top-quark production in $pp$ collisions at $\sqrt{s}=13$ TeV with …
2019
The detector-level minimax-m(bl) distribution for events entering the same-sign lepton control region.
Synthesis and Structural Characterization of Substituted 2-Phenacylbenzoxazoles
2013
1 H and 13C NMR spectra of eleven 2-phenacylbenzoxazoles (ketimine form) show that their CDCl3-solutions contains also (Z)-2-(benzo[d]oxazol-2-yl)-1-phenylethenols (enolimine form). Intramolecular hydrogen bonding in the latter tautomer was found to be significantly weaker than that one in respective (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines. Integrals of the 1 H NMR signals were used to evaluate the molar ratio of the tautomers. Strong electron-donating substituents were found to stabilize the ketimine tautomer. pKT (negative logarithm of the equilibrium constant, KT = [ketimine]/[enolimine]) was found to be linearly dependent on the Hammett substituent constant σ. The results of the MP2 ab…
Multinuclear magnetic resonance and x-ray diffraction studies of aminonitropyridines
1992
The 15N NMR spectra for 21 aminonitropyridines were measured and their chemical shifts assigned. The 1H and 13C NMR chemical shifts and spin–spin coupling constants were also determined for 16 compounds of this series. In order to relate the structural properties of nitramino groups and their 15N NMR chemical shifts in 2- and 4-nitramino-3-nitropyridines, which differ remarkably from all other amino groups studied, low-temperature 1H NMR, 17O NMR, comparative INEPT and IR spectroscopic studies were carried out. In addition, the x-ray crystal structure of 2-nitramino-3-nitropyridine was determined. Comparative spectroscopic studies showed that the nitramino derivatives exhibit different char…
1H,13C and15N NMR spectroscopic, x-ray structural andab initio/HF studies on nitramino andN-alkylamino-4-nitro derivatives of pyridineN-oxides and py…
2003
The 1H, 13C and 15N NMR spectra in DMSO-d6 were measured for eight nitraminopyridine N-oxides, ten 4-nitropyridine N-oxides, four 2-nitraminopyridines and five 4-nitropyridines. Their chemical shift assignments are based on PFG 1H,X (X = 13C and 15N) HMQC and HMBC experiments. The relative energies for the tautomers of two nitraminopyridine N-oxides were determined by ab initio HF/6–311G** calculations. A single-crystal x-ray structural analysis was made for 4-methyl-2-nitraminopyridine: C6H7O2N3, M = 153.15, triclinic, space group P-1 (No. 2), a = 7.0275(4), b = 6.8034(3), c = 8.6086(5) A, α = 103.620(2), β = 90.309(2), γ = 122.215(3)°, V = 334.11(3) A3, Z = 2. Copyright © 2003 John Wiley …
13C and15N NMR chemical shift assignments ofN-1-(2- azidoethyl)-4-R-pyrimidin-2-ones by1H,X HMQ(B)C withz-gradient selection
1998
13C and 15N NMR chemical shift assignments based on z-gradient selected 1H,X (X=13C and 15N) HMQC and HMBC experiments are reported for N-1-(2-azidoethyl)pyrimidin-2-one (ring system of cytosine), its five 4-R derivatives [where R=NH2, OCH3, N(CH2)4, NHCH2CH(CH3)2 and N(CH3)2] and 2-azidoethyl tosylate. The possibilities of detecting all nitrogens in these molecules containing (i) an azido group at N-1 and (ii) an electronegative substituent at C-4 are limited. First, the terminal nitrogen of the azido group is difficult to observe because the nearest proton (in a CH2 group) is located four bonds away from it. Second, in contrast to N-1, N-3 in N-1-(2-azido-ethyl)-4-pyrimidin-2-ones remaine…
Nitramino, NRNO2 (R = H, CH3), as a substituent.13C and15N NMR spectroscopic study of nitraminobenzenes and -pyridines
1993
In order to clarify the special properties of the aryl-bound nitramino substituent NRNO 2 (R=H, CH 3 ), 13 C and 15 N NMR spectra of six nitraminobenzenes and nine nitraminopyridines were measured in DMSO-d 6 and their chemical shifts assigned. 1 H NMr chemical shifts and spin-spin coupling constants of all the compounds were also determined. In contrast to the behaviour of nitropyridines or -benzenes studied previously, most of the present compounds gave very broad 17 O NMR lines even at elevated temperatures and their 17 O NMR data were not useful for any reliable conclusions
Correlation between the molecular structure and the kinetics of decomposition of azamacrocyclic copper(II) complexes
2015
The formation of copper(II) complexes with symmetrical dinucleating macrocyclic ligands containing two either monomethylated (L1) or trimethylated (L2) diethylenetriamine (Medien or Me3dien) subunits linked by pyridine spacers has been studied by potentiometry. Potentiometric studies show that L1 has larger basicity than L2 as well as higher stability of its mono- and binuclear complexes. The crystal structures of L1·6HCl (1), [Cu2(L1)Cl2](CF3SO3)2 (2), [Cu2(L1)(OH)](ClO4)3·3H2O (3) and [Cu(L1)](ClO4)2 (4) show that L1 adopts different coordination modes when bound to copper(II). Whereas in 2, each copper(II) is bound to one Medien subunit and to one pyridine group, in 3 each metal center i…
Über antimon-haltige heterocyclen
1980
Abstract p -Nitrophenyl- and p -tolyl-oxadithia- and trithiastibocanes have been synthesized from the respective aryldichlorostibane and dithiole. The compounds have been characterised by means of 13 C NMR and vibrational spectra (ν(SBS 2 ) 350–320 cm −1 ). The crystal structure of p -nitrophenyltrithiastibocane has been determined ( R = 0.042). The eight-membered ring exhibits a boat-chair conformation. Single-bond distances of SbC and SbS (219, 244 and 245 pm), a 1,5-transannular Sb⋯S interaction (319 pm), and Sb⋯S and Sb⋯O (339 and 353 pm) intermolecular contacts, result in a six-coordinated Sb III (ψ-monocapped octahedral) species. The two additional Sb⋯S distances are in accordance w…
Synthesis, structural and magnetic characterizations of new complexes of di-2,6-(2-pyridylcarbonyl)pyridine (pyCOpyCOpy) ligand
2013
International audience; Using the di-2,6-(2-pyridylcarbonyl)pyridine ligand (L1) as starting framework, five new mononuclear complexes were obtained: [Cu(L1)(MeCN)(ClO4)2] (1) [Co(L1)(MeCN)(Br)2]*MeCN (2), [Fe(L1)2](BF4)2*MeOH*H2O (3), [Cr(L2a)Cl2]*2MeOH (where HL2a is (6-(hydroxyl(methoxy)(pyridin-2-yl)methyl)pyridin-2-yl)(pyridin-2-yl)methanone) (4) and one trinuclear [NiII3] complex, [Ni3(L2b)2(Bz)2(EtOH)2](ClO4)2*2EtOH (where HL2b is (6-(hydroxyl(ethoxy)(pyridin-2-yl)methyl)pyridin-2-yl)(pyridin-2-yl)methanone; Bz = benzoato) (5). Their structural and magnetic characterizations are herein reported. All the metal ions show octahedral coordination geometry, which is slightly unusual for t…