Reaction of carboxamide with Cu2Oisonitrile complex; formation of a new chelated copper(I) complex

Reaction of carboxamides with Cu₂O in the presence of t-butyl isocyanide gave new chelated copper(I) complexes, which probably are formed by the insertion of t-butyl isocyanide into the coppernitrogen bond of copper(I) amide isonitrile complexes, which were initially produced from the carboxamides and Cu₂Ot-butyl isocyanide complex. The same chelated copper(I) complexes were prepared more readily by the reaction of the corresponding N-trimethylsilyl-carboxamides with Cu₂Ot-butyl isocyanide complex. Reactions of the copper(I) complexes thus obtained with alkylating agents, such as alkyl halides, alkyl tosylates and triethyloxonium tetrafluoroborate, also were described.     

The vibrational spectra and normal coordinate analysis of tetracyclopropyllead

All the fundamental frequencies observed in IR and Raman spectra have been assigned to the normal modes of the molecule (C₃H₅)₄Pb (C₃H₅ = cyclopropyl). The calculated force field is compared to that of (C₃H₅)₂Hg and the Cmetal stretching force constants are discussed along with those of Me₄Pb and Me₂Hg; The similarity of the spectra of cyclopropyllead and cyclopropyl-mercury proves that the vibrations of cyclopropyl structural units are isolated in both molecules.     

Preparation and properties of the formamidino complexes [M(π-C5H5){HC(NR)2}(CO)2] (M = molybdenum or tungsten; R = aryl or alkyl)

The preparation and properties of the complexes [M(π-C₅H₅){HC(NR)₂}CO)₂] (M = Mo, W; R = aryl or alkyl) are reported. The complex [Mo(π-C₅H₅){HC(N-p-tolyl)₂}(CO)₂] could be prepared by (a) reaction of MoCp(CO)₃Cl with M′{HC(N-p-tolyl)₂} (M′ = K, Ag or Cu); (b) irradiation of MoCp(CO)₃Cl with HC(HN-p-tolyl)N-p-tolyl); and (c) reaction of [MoCp(CO)₃]₂ with M′{HC(N-p-tolyl)₂} (M′ = Ag or Cu). The several routes to this complex give indications of the mechanisms of formation. The structure of these complexes and the bonding nature of the metal with the formamidino group is discussed on basis of the ¹H and ¹³C NMR and IR spectra.Reaction of N,N′-dimethyl formamidine with MCp(CO)₃Cl gave the complex [M(π-C₅H₅){HC(NMe)N(CO)Me}(CO)₂], containing a carbonyl inserted between the metal and the formamidino group. Irradiation of this carbamoyl complex caused decarbonylation, yielding the complex [M(π-C₅H₅){HC(NMe)₂}CO)₂].     

Directed 2-azonia-[3,3]-sigmatropic rearrangements. a convenient preparation of substituted 1-azaspiro[4,5]decanes

3-Acetylpyrrolidines are prepared from 5-methyl-5-vinyloxazolidines in a reaction which involves a directed 2-azonia-[3,3]-sigmatropic rearrangement.     

Polynuclear isocyanide complexes of rhenium

The arylation of carbonylgold chloride with diarylzinc compounds yields either triarylgoldzinc or diarylgoldzinc chlorides, depending on the reactant ratio and the nature of the aryl group. The same reactions with diphenylcadmium and diphenylmercury yield exclusively diphenylgoldcadmium chloride and diphenylgoldmercury chloride, respectively. The reactions of the products with N,N,N′,N′-tetramethylethylenediamine and triphenylphosphine were studied.Phenylgold has been obtained as a very unstable solid from diphenylgoldzinc chloride and diphenylgoldmercury chloride.     

Dicyclopentadienyl-η1-cyclooctatrienyltitanium and dicyclopentadienyl-η3-cyclooctatrienylniobium

Dicyclopentadienyl-η¹-cyclooctatrienyltitanium and -η³-cyclooctatrienylniobium are prepared from (C₅H₅)₂MCl₂ (M = Ti, Nb) and two equivalent amounts of i-PrMgCl in the presence of an excess of cyclooctatetraene. For the preparation of (C₅H₅)₂NbC₈H₉ the presence of NaBH₄ is also necessary. The products obtained are characterized by IR, mass and ¹H NMR spectroscopy. Reactions with HCl, thermal decomposition reactions, magnetic measurements and elemental analyses were performed to establish the structures.     

Carbon-13 nuclear magnetic resonance studies of some phosphonium,arsonium, sulfonium and pyridinium keto-stabilized salts,and ylides and of their palladium(II) complexes

The ¹³C chemical shifts, the ¹³C³¹P coupling constants, and some one-bond ¹³C¹H coupling constants were measured for the title compounds. For the ylides of phosphorus, arsenic and sulfur, the data are consistent with an sp²-hybridized ylidic carbon with a strong, localized negative charge, while for the pyridinium ylide this charge is much more delocalized. in the homologous series of salts the electron-withdrawing ability of the groups studied varies in the order: Ph₃P⁺ < Ph₃As⁺ « Me₂S⁺ « Me₂C₅H₃N⁺. The differences in the carbonyl chemical shift between the ylides and the corresponding salts are a measure of the resonance stabilization of the negative charge in the form X⁺CCO^?; this stabilization varies with the groups studied in the order: Ph₃P⁺ < Ph₃As⁺ ≈ Me₂S⁺ « Me₂C₅H₃N⁺. The ylide—palladium(II) complexes contain a bond between the ylidic carbon and the metal: the ylidic carbon is shifted upfield in the complex with respect to the free ligand, while the adjacent carbonyl is shifted strongly downfield. These data suggest that the PdC(1) bond is strongly polarized with a high electron density on the C(1) atom which cannot be delocalized through resonance as in the free ligands.     

Conjugated circuits and resonance energies of benzenoid hydrocarbons

A concept of conjugated circuits contained in Kekulé forms of benzenoid hydrocarbons is considered. Circuits of size (4n + 2) in which CC single and double bonds formally alternate are enumerated and serve as the basis for the characterization of a given system. Resonance energies of benzenoid systems are given by contributions of conjugated circuits of different size. The scheme permits the expression of resonance energies of different molecules in terms of selected reference compounds, such as linear acenes. The approach is illustrated on a dozen benzenoid hydrocarbons and the calculated resonance energies are on average within 0.05 eV of the values obtained by SCF MO calculations.