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51.
Summary The reactions of MCl4 (M = Ti or V) with R2P(S)P(S)R2 (R = Me or Et) yield hexacoordinate complexes MCl4 · R2P(S)P(S)R2 (M = Ti or V; R = Me or Et), whereas similar reactions with VOCl3 lead to reduction of vanadium and give rise to the vanadium(IV) pentacoordinated complexes: VOCl2-R2P(S)P(S)R2 (R = Me or Et). All the compounds have been characterized by elemental analyses, i.r., visible and e.p.r. spectra, which show thecis-chelate character of these ligands, although in the complexes containing Et4P2S2 the i.r. spectra indicates that thegauche conformation of the ligand is implicated in bonding to the metal. The occupation of the sixth coordination site in pentacoordinate complexes, VOCl2 · R2P(S)P(S)R2, by different donor solvents, has been studied by means of visible and e.p.r. spectra. 相似文献
52.
R. Usón A. Laguna J. Vicente J. García B. Bergareche 《Journal of organometallic chemistry》1979,173(3):349-355
(Pentahalophenyl) (p-tolylisocyanide)gold(I) complexes were prepared by treating Au(C6X5) (tetrahydrothiophen) (X = F, Cl or Br) with p-MeC6H4NC. Their reactivity toward nucleophiles was studied and found to decrease in the sequence: primary amines > ammonia > secondary amines > aromatic amines > alcohols; the effects of the various C6X5 groups were less pronounced, but decreased according to C6F5 > C6Cl5 > C6Br5.Twenty-five novel gold(I) carbene derivatives were isolated. 相似文献
53.
R. Usón L.A. Oro D. Carmona M.A. Esteruelas C. Foces-Foces F.H. Cano S. García-Blanco A.Vázquez De Miguel 《Journal of organometallic chemistry》1984,273(1):111-128
A new series of cationic areneiridium(I) complexes of formula [Ir(barrelene)(arene)]+ or [Ir(barrelene)(PhNRPh)]+ (R= Ph or H) have been synthesized from neutral iridium complexes of the type [IrY(barrelene)]x (barrelene = Me3TFB, Y = Cl or OMe (x = 2), Y = acac (x = 1); barrelene = TFB, Y = OMe (x = 2), Y = acac (x = 1)). The crystal structures of [Ir(Me3TFB)(1,4-C6H4Me2)]ClO4 and [Ir(TFB)(PhNPh2)]BF4·CH2Cl2 have been determined by X-ray diffraction. They crystallize in the space groups Pbca and Pna21 respectively with lattice constants of 17.6947(11), 15.8072(10), 16.0019(11) Å and 9.8059(2), 20.8097(9), 14.3367(4) Å. Final R factors were 0.063 and 0.042 for the observed data. Both complexes show a staggered arrangement between the arene and the TFB moieties and deviation from planarity of the coordinated arene ligands. In the second complex the IrC and NC distances, the CNC angle, the type of arene puckering, and the spectroscopic data indicate a distortion of the coordinated arene towards a η5-coordinated iminocyclohexadienyl form. 相似文献
54.
Ângela F. S. S. Mendonça Dina T. R. Formigo Isabel M. S. Lampreia 《Journal of solution chemistry》2002,31(8):653-670
Solubilities of triethylamine in aqueous tetraethylammonium chloride solutions were measured at 20, 25, and 35°C. The molalities in Et4NCl of the aqueous solvents ranged from 0.03 to 1 mol-kg–1. The data were evaluated from density measurements using a vibrating-tube densimeter. At each temperature, least-squares method was used to fit experimental density data points to double polynomial equations of various degrees. Triethylamine molalities of the saturated aqueous phases were estimated by extrapolation from those equations. Experimental data were interpreted in terms of hydrophobic and electrostatic perturbed domains in the hydration shells of the noneleceory and of the cation of the salt, as a function of temperature and salt concentration. The conclusions obtained are consistent with previous volumetric studies. 相似文献
55.
Gómez I Olivella S Reguero M Riera A Solé A 《Journal of the American Chemical Society》2002,124(51):15375-15384
The ground state (S(0)) and lowest-energy triplet state (T(1)) potential energy surfaces (PESs) concerning the thermal and photochemical rearrangement of bicyclo[3.1.0]hex-3-en-2-one (8) to the ketonic tautomer of phenol (11) have been extensively explored using ab initio CASSCF and CASPT2 calculations with several basis sets. State T(1) is predicted to be a triplet pipi lying 66.5 kcal/mol above the energy of the S(0) state. On the S(0) PES, the rearrangement of 8 to 11 is predicted to occur via a two-step mechanism where the internal cyclopropane C-C bond is broken first through a high energy transition structure (TS1-S(0)()), leading to a singlet intermediate (10-S(0)()) lying 25.0 kcal/mol above the ground state of 8. Subsequently, this intermediate undergoes a 1,2-hydrogen shift to yield 11 by surmounting an energy barrier of only 2.7 kcal/mol at 0 K. The rate-determining step of the global rearrangement is the opening of the three-membered ring in 8, which involves an energy barrier of 41.2 kcal/mol at 0 K. This high energy barrier is consistent with the fact that the thermal rearrangement of umbellulone to thymol is carried out by heating at 280 degrees C. Regarding the photochemical rearangement, our results suggest that the most efficient route from the T(1) state of 8 to ground state 11 is the essentially barrierless cleavage of the internal cyclopropane C-C bond followed by radiationless decay to the S(0) state PES via intersystem crossing (ISC) at a crossing point (S(0)()/T(1)()-1) located at almost the same geometry as TS1-S(0)(), leading to the formation of 10-S(0)() and the subsequent low-barrier 1,2-hydrogen shift. The computed small spin-orbit coupling between the T(1) and S(0) PESs at S(0)()/T(1)()-1 (1.2 cm(-)(1)) suggests that the ISC between these PESs is the rate-determining step of the photochemical rearrangement 8 --> 11. Finally, computational evidence indicates that singlet intermediate 10-S(0)() should not be drawn as a zwitterion, but rather as a diradical having a polarized C=O bond. 相似文献
56.
Ignacio H. Sánchez María Isabel Larraza Fernande Basurto Ricardo Yaf?ez Salvador Avila Ricardo Tovar Pedro Joseph-Nathan 《Tetrahedron》1985,41(12):2355-2359
(±)--methylperezone () was obtained by selective oxidative demethylation of (±)-leucoperezone trimethyl ether (). Compound () was prepared by condensation of 2,3,5-trimethoxytoluene () with 6-methyl-5-hepten-2-one, followed by reductive removal of the tertiary alcohol. The aromatic precursor was prepared in four steps from 2,3-dimethoxytoluene () and, alternatively, in three steps from 5-bromoveratraldehyde (). Racemic and were directly compared with the optically active molecules prepared from natural R(-)-perezone (). 相似文献
57.
R. Usón L.A. Oro M.A. Ciriano D. Carmona A. Tiripicchio M.Tiripicchio Camellini 《Journal of organometallic chemistry》1982,224(1):69-80
The preparation and properties of complexes of general formulae [Rh(CS)-(HL)(PR3)2]ClO4 (HL = pyrazole (HPz), 3-methylpyrazole (H3-MePz), 3,5-dimethylpyrazole (H3,5-Me2Pz), PR3 = triphenylphosphine, tricyclohexylphosphine) and [(PR3)2(CS)Rh(μ-Pz)AuPPh3]ClO4 are reported. Complexes of the first set react with potassium hydroxide to give [Rh(μ-L)(CS)(PPh3)2 or RhPz(CS)(PR3)2 complexes. The structure of the complex [Rh(3,5-Me2Pz)(CS)(PPh3)]2 has been determined by X-ray diffraction methods. The crystals are monoclinic, space group P21/c, with Z = 4 in a unit cell of dimensions a = 12.700(11), b = 17.217(16), c = 23.041(18) Å, β = 116.55(8)°. The structure has been solved by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.059 for 1978 independent reflections. The structure consists of dimeric complexes, in which each rhodium atom is in a square-planar environment being bonded to a carbon atom of a thiocarbonyl ligand, a phosphorus atom of a triphenylphosphine molecule and to two nitrogen atoms of pyrazolate ligands bridging the metal atoms. The dihedral angle of 71.1° between such two square planes leads to a bent configuration with an intramolecular rhodium-rhodium distance of 3.220 Å. The thiocarbonyl and triphenylphosphine ligands are in a trans disposition. 相似文献
58.
Summary The reduction of nickel(II) halides with NaBH4 in the presence of different ligands, L=PPh3, AsPh3, SbPh3, has been studied. With a molar ratio L/Ni=3, new complexes NiX(SbPh3)3, X=Cl, Br, I, were obtained. With a molar ratio L/Ni=2, dimeric species [NiXL2]2, X=Cl, Br, I; L=PPh3, AsPh3, SbPh3, were isolated. They are unstable and decompose easily in the solid and rapidly in solution, so that pure samples were only identified for X=Cl, L=PPh3, AsPh3, SbPh3; X=Br, L=PPh3 and X=I, L=PPh3. With a molar ratio L/Ni=1, complexes [NiXL]n (probably polymeric) were obtained. They are very unstable and pure samples could only be isolated when X=Cl, L=PPh3. Impure substances containing variable amounts of decomposition products were obtained in all the remaining cases. The chemical and structural behaviour of these complexes is discussed. 相似文献
59.
Daniel Carmona Roberto Medrano Isabel T. Dobrinovich Fernando J. Lahoz Joaquina Ferrer Luis A. Oro 《Journal of organometallic chemistry》2006,691(26):5560-5566
Half-sandwich complexes of formula [(ηn-ring)MClL]PF6 [L = (S)-2-[(Sp)-2-(diphenylphosphino)ferrocenyl]-4-isopropyloxazoline; (ηn-ring)M = (η5-C5Me5)Rh; (η5-C5Me5)Ir; (η6-p-MeC6H4iPr)Ru; (η6-p-MeC6H4iPr)Os] have been prepared and spectroscopically characterised. The molecular structures of the rhodium and iridium compounds have been determined by X-ray crystallography. The related solvate complexes [(η5-C5Me5)ML(Me2CO)]2+ (M = Rh, Ir) are active catalysts for the Diels-Alder reaction between methacrolein and cyclopentadiene. 相似文献
60.
Rita Aparecida Zoppi Maria Isabel Felisberti Marco-Aurelio De Paoli 《Journal of polymer science. Part A, Polymer chemistry》1994,32(6):1001-1008
This work describes the preparation of polypyrrole and EPDM rubber blends, PPy/EPDM, by the sorption of pyrrole (vapor phase) in an EPDM matrix containing CuCl2. We investigated the effect of the oxidant particle-size on the sorption and polymerization equilibrium, electrical conductivity, and mechanical properties of the blends. Independently of the CuCl2 concentration and polymerization time, the polypyrrole weight fraction in the blend, Xppy, increases when the oxidant particle-size in changed from 150–250 μm to smaller than 106 μm. For blends containing 50 phr of CuCl2, obtained following 72 h of exposure to pyrrole, an increase in the Young's Modulus (from 2.2 ± 0.2 to 3.9 ± 0.6 MPa) and an increase in the electrical conductivity (from 10?9 to 10?7 S cm?1) was observed when the oxidant particle-size was decreased. Infrared spectroscopy, thermogravimetric analysis, scanning differential calorimetry, and scanning electron microscopy were used in sample characterization. © 1994 John Wiley & Sons, Inc. 相似文献