The cyclometallated monohydrides (R H or Me) react with NaOPri/PriOH/H2 to give fluxional tetrahydrides, probably . These are highly fluxional having magnetically equivalent hydridic hydrogens, even at ---100°C. When treated with HBr, , gives and with CO it gives a mixture of complexes which are probably (2 isomers) and . When treated with ButNC this tetrahydride undergoes similar reactions but another (major) product is formed which appears to be binuclear and fluxional and is probably of type , with four bridging hydrogens. 相似文献
(R = 2,4,6-tri-t-butylphenyl) and (R = 2,4,6-tri-t-butylphenyl) are two new nickel complexes with a 1,3-diphosphaallyl ligand. Both structures have been determined by X-ray analysis. 相似文献
The formation of newintermediates and especially germaimines R2GeNR′ has been observed in the reaction of germylenes with phenyl azide (precursor of phenylnitrene). These transient derivatives lead, by polycondensation reactions, to the corresponding cyclic or linear germazanes , and are characterized by insertion reactions into the germanium—nitrogen bond, cleavage and addition reaction with tetrahydrofuran, and pseudo-Wittig reactions with benzaldehyde. The latter produces the corresponding germoxanes via new intermediates and phenyl benzaldimine. 相似文献
Di-t-butylzinc adds easily to conjugated enynes . Only the acetylenic bond is involved in this reaction which proceeds via trans-addition. This regioselective and stereoselective addition leads to conjugated dienes . 相似文献
The photolysis of 2,4,4-trimethyl-4-sila-3-methylene-l,5-hexadiene yielded 2,2,4-trimethyl-3-methylene-2-silabicyclo[2.1.1]hexane as the only volatile photoproduct in high yield. However, 2,4,4-trimethyl-4-sila-3-methylene-1,6-heptadiene was found to be photochemically non-reactive under identical reaction conditions, and the 1-substituted butadienes (VI) and (VIII) underwent cis-trans isomerism on photolysis. 相似文献
To throw more light on the nature and character of the metalhydrogenmetal bond we carried out the electronic structure calculations by use of the parameter-free Fenske-Hall method and the semi-empirical EHT method for complexes (M = Mn, Re, Cr, Mo, W and n = −2,0). The character and stability of the double hydrogen bridges in these complexes and in and were compared. The effects that type of transition metal has on the character and stability of double hydrogen bridges in carbonyl dimers are described. The electronic structures of the bridge cores in the double-and single-hydrogen bridge binuclear carbonyls of chromium and molybdenum were compared. 相似文献
The 13C NMR spectra of iridium complexes of 1,5-cyclooctadiene are reported and discussed. For compounds containing β-diketonato ligands, a correlation is found between the ethylenic carbon chemical shifts and the Swain and Lupton and values of the substituents of the β-diketonato ligand. The relationship is satisfactorily explained by considering the Dewar, Chatt and Duncanson model of bonding. Tentative interpretation of the observed chemical shifts of the other carbons is presented. 相似文献
Careful addition of 1,3-dibromopropane to magnesium in Et2O yields 1,3-bis(bromomagnesio)propane which is purified via “magnesacyclobutane” . Reactions of with H2O, CO2, HgBr2 and Me3SnCl are reported. MgBr2 catalyses the decomposition of to allylmagnesium bromide . 相似文献
Substituted vanadium carbonyl compounds with η2-bonded acyl ligands (η2-RCO)V(CO)3 ( = ditertiary phosphines or arsines: dppe, dppp, dppm, diars, arphos, dpase) have been prepared by photochemical reaction of [V(CO)4] with various substituted benzoyl chlorides and cyclopropanylcarbonyl chloride.Effects of aromatic substituents and upon the thermal stability of the η2-acylcarbonylvanadium compounds are discussed. IR ν(CO) force constants and 51V NMR signals are linearly correlated with Hammett's σ constants of the aromatic substituents.The preparation of V(CO)2Cl(diars)2 is described. 相似文献
Ring opening of the glycidonitriles (II a–e) by HF/pyridine leads to the fluorocyanohydrins (III a–e). Treatment of the fluorocyanohydrins with ammonia in anhydrous methanol gives the α-amino-β-fluoronitriles (IV a–e) which upon acidic hydrol sis afford the β-fluoro-α-aminoacids (V a–e) in good overall yield.相似文献
Theoretical consideration reveals a unique relationship between NMR spectral parameters and possible types of the gramididin A spatial structure. By means of two dimensional NMR spectroscopy four distinct species were detected simultaneously in ethanol solution. Comparison of experimental data and theoretical conclusions demonstrates that species 1 and 2 are left-handed parallel double helices differing in relative arrangement of the two polypeptide chains within the dimers, species 3 is left-handed antiparallel double helix , and species 4 is a mirror image of species 1, i.e. right-handed parallel double helix . The results are compared with those on spatial structures of the peptide in complex with cesium (right-handed antiparallel double helix ) and of the gramicidin A transmembrane ionchannel (N-terminal to N-terminal single-stranded dimer ). 相似文献
A series of o-tropyliobiphenyl tetradfluoroborates has been synthesized. Evidences are presented to show that exhibit strong intramolecular charge-transfer interaction between tropylium ion and remote aryl ring. The structure of was determined by single crystal X-ray diffraction study. 相似文献
Chlorine fluorosulfonate adds exceptionally easy not only to various alkenes, perfluorobenzene, but to alkynes too The addition of peroxydisulfuryldifluoride to alkyl- and perfluoroalkyliodides leads to unstable adducts, which decompose with the formation of alkylfluorosulfonates and iodine fluorosulfonate; the latter was trapped with fluoroalkenes The use of ClOSO2F allows to substitute selectively for the fluorosulfonate group the chlorine atom in monochloroacetic acid esters as well as the fluorine atom in hexafluoroacetone N-fluoroimine ClOSO2F serves as an exceptionally active chlorinating reagent for fluorinated alcohols, nitrosocompounds, perfluoroacid amides and particularly for benzene The reaction of (OSO2F)2 with perfluoroacid amides leads to the corresponding N,N-bis(fluorosulfonate)amides, which easily rearrange into alkylfluorosulfonates The hypochlorites of fluorinated alcohols are stable enough and they, similarly to ClOSO2F, are able to add to alkenes, fluoroalkenes (but not to perfluoroisobutylene), bis(trifluoromethyl)ketene, trifluoromethylisocyanate and perfluoronitriles The fluorosulfonatoacetic acid esters are unstable at the ambient temperature, but they can be widely used in situ as a very effective alkylating reagents 相似文献
Glyoxaldiimines (I) RN=CHCH=NR show in the NMR a downfield shift of glyoxalic protons (Hgly) when complexed to (II: M = Mo, W), but increasing high field shifts when going to (III) and complexes (IV). In the tungsten complexes II HglyW coupling satellites are resolved (J(WH) ≈4–6 Hz); in the phosphine compounds III, IV long range PHgly coupling is clearly visible. Mechanisms of spinspin interaction are briefly discussed in connection with the EPR results on monoanionic radicals of II–IV. 相似文献
A silicon deuteride DH exchange reaction demonstrates the reductive characteristics of saturated Grignard reagents catalytically activated by nickel complexes. Application of this reaction to the organosilanes R1R2R3SiX(X=OCH3,F,Cl) provides a new method for their reduction. The reduction takes place with retention of configuration at the silicon atom for methoxy. and fluorosilanes. However inversion of configuration occurs in the case of chlorosilanes.The new type of reaction can also be used for the reduction of vinylsilanes The results show the reductive properties of the Ni-H bond formed by β-elimination of the Ni-R intermediate. 相似文献
“doping-addition” of 2-NO2C6H4SCl to the tricyclo[4,2,2,02,5]deca-3,7,9-triene system occurs to give unusual products: (i) rearranged caged cyclopropane and (ii) the stable cross-perchlorate . 相似文献
The stereoselective fluorination of four couples of diastereoisomeric 2-alkyl 3-hydroxy 3-phenylpropanoic methyl esters by the reaction of the phenyltetrafluorophosphorane with the corresponding trimethylsilylethers derivatives is described. The structure of the 2-alkyl 3-fluoro 3-phenyl propanoic methyl esters obtained quantitativly has been determined unambiguously by NMR analysis. 19F NMR results permit us to determine the relative populations of the rotamers for each of the isomers threo and erythro. 相似文献