1,721,164 research outputs found
Reactivity of iron tricarbonyl cycloheptatrienide. Synthesis of metal carbonyl ditropylium complexes(C14H14FeM(CO)6) (M= iron, chromium, molybdenum, tungsten)
No full textReaction of the fluxional compd. [C7H7Fe(CO)3]- (I) with allyl halides gives as the final product (OC)3FeC7H7-
C7C7Fe(CO)3, which shows a different stereochem. from the similar mixed (OC)3FeC7H7-C7H7M(CO)3 derivs.
obtained by reaction of I with [-C7H7M(CO)3]+ (M = Cr, Mo, W)
Transition-metal-catalyzed cyclization of [a,c] biladiene salts as an efficient route to the synthesis of alkyl porphyrins
No full textSeveral alkyl porphyrins have been synthesized by cyclization of different 1,19-dimethyl [a,c]biladiene dihydrobromides, catalyzed by rhodium, ruthenium and chromium salts in buffered alcoholic media. When the reactions were carried out without base, a drastic reduction of porphyrin yields was observed. No substantial differences were observed on changing the solvent. A different reaction pathway was seen when the 1,19-substituent groups were bulkier than methyl. © 1990
Synthesis of unsymmetrical porphyrin dimers containing beta-octaalkyl and meso-tetraphenylporphyrin subunits
No full textMethodology for synthesis of phenyl-linked unsymmetrical dimers containing 8,12-diethyl 2,3,7,12,13,17,18-hexamethylporphyrin and meso-tetraphenylporphyrin subunits is reported. Hetero metal complexes of these dimers can be prepared by following two different routes. Copyright (C) 1996 Elsevier Science Lt
Heavy Neutral Leptons from low-scale seesaws at the DUNE Near Detector
Full text linkHeavy nearly-sterile neutrinos are a common ingredient in extensions of the Standard Model which aim to explain neutrino masses, like for instance in Type I seesaw models, or one of its variants. If the scale of the new Heavy Neutral Leptons (HNLs) is sufficiently low, observable signatures can arise in a range of current and upcoming experiments, from the LHC to neutrino experiments. In this article, we discuss the phenomenology of sterile neutrinos in the MeV to GeV mass range, focusing on their decays. We embed our discussion in a realistic mass model and consider the resulting implications. We focus in particular on the impact on the signal of the strong polarisation effects in the beam for Majorana and (pseudo-)Dirac states, providing formulae to incorporate these in both production and decay. We study how the Near Detector of the upcoming Deep Underground Neutrino Experiment can constrain HNL states by searching for their de- cay products inside the detector. We conduct a Monte Carlo background analysis for the most promising signatures, incorporating the detector's particle identification capabilities, and estimate the experimental sensitivity of DUNE to these particles. We also present an estimate of the nu (tau) -derived HNL flux at DUNE, currently missing in the literature, which allows us to discuss searches for HNLs at higher masses
Fast atom bombardment mass spectral observations on some beta-halogenated tetraphenylporphyrins and their iron derivatives
No full textThe fast atom bombardment mass spectral observations on some P-halogenated tetraphenylporphyrins and their iron derivatives were compared in order to investigate the relative stability of these complexes, The investigated compounds are represented as O[FeBr4TPP](2), O(FeTPP)(2), O[FeTPP(4-Br)](2), O[FeTPP(4-OCH3)](2), H-2(Br4TPP), Fe(Br4TPP)Cl, H-2(Cl16TDCDMPP) and Fe(Cl16TDCDMPP)Cl where Br4TPP is the dianion of 7,8,17,18-tetrabromo-5,10,15,20-tetraphenylporphyrin, TPP is the dianion of 5,10,15,20-tetraphenylporphyrin, TPP(4-Br) is the dianion of 5,10,15,20-tetra(4-bromo)phenylporphyrin, TPP(4-OCH3) is the dianion of 5,10,15,20-tetra-(4-methoxy)-phenylporphyrin and Cl16TDCDMPP is the dianion of 2,3,7,8,12,13,17,18-octachloro,5,10,15,2 tetra-(2,6-dimethoxy,3,5-dichloro) phenylporphyrin, The stability of each molecular ion and the subsequent fragmentations were correlated to the substitution of the porphyrin rings and to the loss of steric hindrance
Towards the periodic table of metallocorrolates: synthesis and characterization of main group metal complexes of octamethylcorrole
No full text[No abstract available
OPTOCHEMICAL HCL GAS-DETECTION BASED ON TETRAPHENYLPORPHINE DISPERSED IN ETHYL CELLULOSE
No full textTo detect sub-ppm levels of dry HCl gas, spectral changes of tetraphenylporphine dispersed in ethylcellulose were examined in the visible region. The Soret and Q-bands of free base tetraphenylporphine are sensitive to sub-ppm levels of HCl with a good reversibility and insensitive to NH3, Cl-2, NO2 and NO at room temperature
Synthesis, characterization, and fluxional behavior of allylic palladium(II) carboxylate and N,N'-diarylformamididocomplexes
No full text[Pd(1-3--allyl)Cl]2 reacts with Li(N,N'-diarylformamidido) forming dimeric complexes I (R = p-MeC6H4, p-ClC6H4, Ph).
1H NMR show the presence of 2 conformers, 1 of which has 2 electronically equiv. allyl groups; their concn. ratio is
independent of the temp., suggesting that no intramol. process takes place. At 80-100° the other conformer undergoes
an intramol. process which brings the 2 allyl groups to equivalence. The presence of weak bridge-splitting ligands, such
as Me2SO or the parent N,N'-diarylformamidine, does not affect the intramol. process, which thus occurs without any
palladium-formamidido bond breaking, probably through a boat inversion of the C2N4Pd2 ring via a chair conformation
Behaviour of polyaniline electrodes in aqueous and organic solutions
No full textPolyaniline (PAn) has been obtained in acidic solutions, chemically (by oxidation with (NH4)2S2O8), and electrochemically (by potential. The reduction/oxidation processes of PAn are basically the same in aqueous acidic solutions and in Li+-containing organic solutions. The fully oxid. © 1988
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