Carbenoid Complexes Research Articles

Preparation of dimethylbis(diphenylphosphinoethane)iron(II) and its decomposition pathways involving the formation of carbenoid intermediates

Reaction of Fe(acac)3, Me2AIOEt, and Ph2– PCH2CH2PPh2(dpe) gives a new methyliron complex, FeMe2(dpe)2 which on thermal decomposition and treatment with CH2Cl2 liberates ethylene, the formation of which suggests the intermediacy of carbenoid complexes.

Carbon-13 NMR spectra of chromium pentacarbonyl carbenoid complexes

The carbon-13 NMR spectra of six carbenoid complexes of the type (OC) 5Cr-(CXX′) have been recorded. The carbenoid carbon atoms are all markedly deshielded (chemical shifts vs. TMS in the range −271 to −360). With only one minor inversion of uncertain significance, the chemical shifts correlate well with the expected ability of the X and X′ groups to engage in dative π bonding to the carbenoid carbon atom. The longitudinal relaxation times for both carbenoid and carbonyl carbon atoms in (OC) 5Cr[C(CH 3)(OC 2H 5)] are 1 – 2 sec. The chemical shift difference for carbonyl carbon atoms cis and trans to the carbenoid ligand is essentially invariant in the six compounds.

Synthetic Reactions by Complex Catalysts. XXVII. Cyclopropane Synthesis Using a Copper Carbenoid from Trichloromethyl Compound, Copper and Isonitrile

Abstract In the previous,1 we reported the cyclopropane synthesis in which - monochloromethylcopper(1)isonitrile (2), a copper carbenoid complex, formed in the reaction of α-monochloro-carbonyl or nitrile (1) with the cu2Ol-isonitrile complex was subjected to the reaction with an electron defecient olefin.

Redox transfer. Part V. Elementary steps. The oxidation of ferrous and cuprous chloride by carbon tetrachloride

The oxidation of ferrous chloride by carbon tetrachloride has been studied spectrophotometrically by initial-rate measurements of FeCl4– formation in acetonitrile as solvent and in the presence of an excess of chloride ion. A transient violet intermediate appears upon mixing of the reagents, considered to be a charge-transfer complex between ferrous chloride and carbon tetrachloride, which decomposes into FeCl4– and a trichloromethyl radical. This decomposition is the rate-determining step in the overall oxidation to ferric chloride. Trichloromethyl radicals are captured by ferrous chloride in a subsequent fast reaction, giving a carbenoid complex which decomposes bimolecularly into ferric chloride and tetrachloroethylene. in the presence of an olefin, dichlorocyclopropanes are also formed. The overall reaction is first-order in ferrous chloride and has a rate constant of 2·10–4l. mole–1 sec.–1 at 22°. The fast interaction of ferrous chloride and trichloromethyl radicals, and the subsequent reactions of the complex formed, are recognized as the main mode of termination in the radical-chain addition of carbon tetrachloride to olefins in a redox transfer-system. The rate constant of the reaction between cuprous chloride and carbon tetrachloride (CCl4+ CuCl[graphic omitted]CuCl2+·CCl3) is about 40 times smaller than the corresponding constant for the ferrous chloride reaction. The reaction reaches a quasi-equilibrium already at conversions into cupric chloride as low as 1·5%.