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81.
Antonio Arcadi Giancarlo Fabrizi Luca M Parisi 《Journal of organometallic chemistry》2003,687(2):562-566
The palladium-catalyzed reaction of aryl iodides with tertiary propargylic amides affords highly substituted allenes. Best results have been obtained by using Pd(OAc)2, nBu3N, HCOOH, and nBu4NCl or LiCl in DME at 100 °C. The reaction is highly regioselective and the carbopalladation step is controlled by the strong directing effect of the tertiary amide group. 相似文献
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85.
Francesco De Sarlo Alberto Brandi Lino Fabrizi Antonio Guarna Neri Niccolai 《Magnetic resonance in chemistry : MRC》1984,22(6):372-375
1H, 13C, 14N and 199Hg NMR data were obtained for organomercury fulminates, RHgCNO (R ? Me, Ph, CNO). The relatively slow relaxation processes effective for the quadrupolar nitrogen muclei of these compounds allow the detection of 199Hg? 14N scalar coupling constants. This feature is ascribed to the presence of low electric field gradients around the 14N nucleus, owing to the presence of the mercury atom. In mercury fulminate, the 199Hg nucleus appears to be coupled with two equivalent 14N nuclei, thus indicating the existence of a covalent structure Hg(CNO)2 in solution. 相似文献
86.
Fabrizi De Biani F Dei A Sangregorio C Sorace L 《Dalton transactions (Cambridge, England : 2003)》2005,(24):3868-3873
The dinuclear bis-iminosemiquinonato [Ru(bpy)(2)(L)(2)Ru(bpy)(2)](PF(6))(2) complex where L is the deprotonated form of N,N'-bis(3,5-di-tert-butyl-2-hydroxyphenyl)-1,3-phenylenediamine (H(4)L), has been synthesised. For comparison purposes, the mononuclear iminosemiquinonato [Ru(bpy)(2)L']PF(6) formed by the N-phenyl-o-aminophenol (H(2)L') was also investigated. Magnetic investigation evidences that the bis-semiquinonato species is characterised by a moderately strong ferromagnetic interaction (H=JS(1) x S(2), J=-85(5) cm(-1)). This result is the theoretically expected one and it is contrasting with the antiferromagnetic interaction observed in previously investigated complexes containing the same ligand. It is suggested that the different behaviour is determined by the different coordination requirements occurring in these complexes. The spectroelectrochemical analysis provides a clear evidence of the valence trapped character of the mono-semiquinonato forms of the ligand. The two mixed valence semiquinonato species containing the quinonato-semiquinonato and semiquinonato-catecholato bridging ligand can be described as class II, but show a significantly different electronic coupling. The electronic factors determining this behaviour are discussed. 相似文献
87.
Cacchi S Fabrizi G Goggiamani A Licandro E Maiorana S Perdicchia D 《Organic letters》2005,7(8):1497-1500
[reaction: see text] The reaction of N,N-dialkylhydrazine/2LiCl adducts with aryl bromides in the presence of Pd(2)(dba)(3) as the palladium source, Xantphos or X-phos as the ligands, toluene as the solvent, and NaOBu-t as the base provides an efficient route to N,N-dialkyl-N'-arylhydrazines. Best results were obtained by using N,N-dialkylhydrazine/2LiCl adducts prepared in situ, omitting their isolation. 相似文献
88.
The influence of structural parameters on the exchange coupling J between metal atoms in end-to-end azido-bridged binuclear complexes of Cu(II) and Ni(II) has been studied by means of density functional calculations. For the case of double-bridged Cu(II) compounds, four ideal pentacoordinate models have been employed in which the coordination spheres of the two metal atoms are either a trigonal bipyramid or a square pyramid, connected through equatorial or axial bridges. The distortion from those ideal geometries along a Berry pathway has also been analyzed. For the hexacoordinate Ni(II) compounds, models with two or one bridging ligands have been studied. The effect of the bridging M-N-N bond angles on the exchange coupling has been analyzed for both the Cu(II) and Ni(II) complexes. 相似文献
89.
Nannini D Tittarelli M Ricci L Conte A Di Emidio B Giovannini A Caporale V 《Journal of AOAC International》2004,87(4):965-971
A model interlaboratory testing scheme was developed by the Italian National Reference Laboratory for Brucellosis. This scheme was planned for both qualitative (Rose Bengal Plate Test; RBPT) and quantitative (Complement Fixation Test; CFT) serological tests and involved a total of 42 laboratories. In the preparation of this scheme, reference was made to general protocols and guidelines and to methods reported in the literature, which were applicable to analytical chemistry laboratories. Six field sera from naturally infected animals, one positive serum at a titer below the European Union (EU) positivity threshold, and 5 sera positive at titers between 20 and 851 International Units of Complement Fixation Test (IUCFT)/mL plus one negative serum were used to produce a panel of test sera. To evaluate laboratory performances in the quantitative test for each tested sample examined, z-scores based on robust summary statistics (the median and normalized interquartile range) were used. To evaluate overall laboratory performance, 2 types of combined z-scores were used: Rescaled Sum of Scores and Sum of Squared Scores. In the case of the qualitative test (RBPT), results were analyzed by a Bayesian approach. A Beta distribution, based on the result of each laboratory, was calculated and used to estimate the probability of each laboratory giving a correct result and its uncertainty. 相似文献
90.
Femoni C Iapalucci MC Longoni G Svensson PH Zanello P Fabrizi de Biani F 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(9):2318-2326
The synthesis and structure, as well as the chemical and electrochemical characterisation of two new nu(3)-octahedral bimetallic clusters with the general [Ni(44-x)M(x)(CO)(48)](6-) (M = Pd, x = 8; M = Pt, x = 9) formula is reported. The [Ni(35)Pt(9)(CO)(48)](6-) cluster was obtained in reasonable yields (56 % based on Pt) by reaction of [Ni(6)(CO)(12)](2-) with 1.1 equivalents of Pt(II) complexes, in ethyl acetate or THF as the solvent. The [Ni(36)Pd(8)(CO)(48)](6-) cluster was obtained from the related reaction with Pd(II) salts in THF, and was isolated only in low yields (5-10 % based on Pd), mainly because of insufficient differential solubility of its salts. The unit cell of the [NBu(4)](6)[Ni(35)Pt(9)(CO)(48)] salt contains a substitutionally Ni-Pt disordered [Ni(24)(Ni(14-x)Pt(x))Pt(6)(CO)(48)](6-) (x = 3) hexaanion. A combination of crystal and molecular disorder is necessary to explain the disordering observed for the Ni/Pt sites. The unit cell of the corresponding [Ni(36)Pd(8)(CO)(48)](6-) salt contains two independent [Ni(30)(Ni(8-x)Pd(x))Pd(6)(CO)(48)](6-) (x = 2) hexaanions. The two display similar substitutional Ni-Pd disorder, which probably arises only from crystal disorder. The structure of [Ni(36)Pd(8)(CO)(48)](6-) establishes the first similarity between the chemistry of Ni-Pd and Ni-Pt carbonyl clusters. A comparison of the chemical and electrochemical properties of [Ni(35)Pt(9)(CO)(48)](6-) with those of the related [Ni(38)Pt(6)(CO)(48)](6-) cluster shows that surface colouring of the latter with Pt atoms decreases redox as well as protonation propensity of the cluster. In contrast, substitution of all internal Pt and two surface Ni with Pd atoms preserves the protonation behaviour and is only detrimental with respect to its redox aptitude. A qualitative rationalisation of the different surface-site selectivity of Pt and Pd, based on distinctive interplays of M--M and M--CO bond energies, is suggested. 相似文献