84 research outputs found
Farther study on the reactivity of cationic dinuclear platinum trihydrido compounds with unsaturated hydrocarbons: Synthesis of μ-hydrido μ-alkylidene complexes, NMR characterization and mechanism insights
No full textThe reactivity of a series of well definite dinuclear platinum complexes [Pt2(L-L)2(H)3][X] ( L-L = dppe, X = BF4, 1a; L-L = dppp, X = BF4, 1b; L-L = dppb, X = BF4, 1c; L-L = dpase, X = BF4, 1d; L-L = dcype, X = Cl, 1e) with unsaturated hydrocarbons is investigated. Compounds 1a, 1c and 1e react with phenylacetylene under mild experimental conditions affording the corresponding μ-hydrido μ-alkylidene complexes [(L-L)Pt(μ-H,μ-CHCH2Ph)][X] 2a, 2c and 2e, independently of the steric and electronic properties of the chelating ligand. Otherwise, the reaction of trihydrides1 with olefins is more sensitive to the ancillary ligand. However, the new compounds [(dpase)2Pt2(μ-H,μ-CHCH2Ph)][BF4], 2d, and [(dppp)2Pt2(μ-H,μ-CHCH3)][BF4], 3b, are obtained in satisfactory yields by reaction of 1d and 1b with styrene and ethylene, respectively. Compound 1e reacts only in the presence of a very large excess of styrene, and it gives a complex mixture of platinum compounds containing 2e and high molecular weight polystyrene as main product. Complexes 2 and 3 are discussed on the basis of multinuclear NMR spectra in solution. 1H and 31P{1H} NMR data show that compound 2d can exist in three different forms with different cis- trans- disposition of phosphorous and arsenic atoms in respect of the bridging ligands. Possible mechanisms for the formation of compounds 2 from the reactions with phenylacetylene or styrene are discussed on the ground of experiments with deuterium labelled reagents
Ionic binuclear platinum(II) hydrides
No full textThe new hydrides [(LL)2Pt2H3][BF4] (I: LL = 1,2-bis(diphenylphosphino)ethane; II: LL = 1,2-bis(diphenylarsino)ethane) were obtained by reaction of (LL)Pt(PzH)2][BF4]2 (PzH = 3,5-dimethylpyrazole) with KBH4 in MeOH or EtOH. © 1977
A series of pyrazole adducts and pyrazolato derivatives of platinum(II) containing various chelating phosphines as ligands: Characterization, 1H and 31P1H NMR spectra
No full textNew pyrazolato derivatives of platinum(II) are isolated, (LL)Pt(pz)2, A, [LL = Ph2P(CH2)nPPh2 (n = 1, 2, 3, or 4), Ph2PCH2CH2AsPh2, (Ph2AsCH2)2 or cis-Ph2PCHCHPPh2; pzH = pyrazole, 3,5-dimethyl,- 3,5-bis(trifluoromethyl)-, or 3,5-dimethyl-4-nitro-pyrazole] by reaction of (LL)PtCl2 with pyrazole and potassium hydroxide in methanol. By protonation of A with fluoboric acid the corresponding pyrazole adducts, [(LL)Pt(pzH)2][BF4]2, B, are obtained when pzH is 3,5-dimethylpyrazole. The properties of the compounds are discussed on the basis mainly of the NMR evidence; 31P data are related to the dimension of the PtP(C)nP ring (n = 1-4) and to the trans-influence of the pyrazolato and pyrazole ligand. © 1982
Platinum(I) dinuclear hydrides
No full textThe novel complexes [(dpe)2Pt2(CO)(H)][X] and [(dpe)2Pt2(CNR)(H)][X] (X = BF′4, I;dpe = 1,2-bis(diphenylphosphino)ethane; R = p-tolyl, methyl and t-butyl) were obtained by reaction of [(dpe)2Pt2H3][X] with CO or isocyanides. © 1979
Carbonylrhodium(I) derivatives of 3,5-dimethyl- and 3,5-bis(trifluoromethyl)pyrazole
No full textBinuclear pyrazolato-bridged complexes such as [(OC)2Rh(μ-pyrazolato-N,N′]2, I or II, were obtained in alkaline solution from (OC)4. © 1981
Trinuclear platinum hydrides
No full textThe isolation of trinuclear platinum cations containing hydrido ligands, viz. [HxPt3(dpe)3]+ and [HxPt3(dpae)3]+, is reported (dpe=(Ph2PCH2)2 and dpae=Ph2PCH2CH2AsPh2). © 1981 Elsevier Sequoia S.A
Positive and negative ion mass spectrometry of carbonylrhodium(I) derivatives of 3,5-dimethyl- and 3,5-bis(trifluoromethyl)pyrazole
No full textThe mass spectrometric behaviour of some carbonylrhodium(I) derivatives of 3,5-dimethyl- and 3,5-bis(trifluoromethyl)pyrazole (pz′H and pz′′ H respectively) has been studied in detail by means of different ionization techniques (Electron Impact and Field Desorption), by recording the positive and negative ion mass spectra and by using linked scan methods for metastables. The species trans-(Ph3P)2(OC)Rh(pz′′ -N) which showed an unexpected behaviour has been investigated by means of collision-al activation experiments. © 1983
Falar de si, falar do outro: o personagem Arturo Bandini de John Fante
No full textThe analyzed novels are linked to the character Arturo Bandini, considered an alter ego of the writer John Fante whose context is that of the Great Depression: Wait Until Spring, Bandini (1938), The Road to Los Angeles (chronologically this is the first novel in the saga, but it was published only posthumously in 1985), Ask the Dust (1939) and Dreams from Bunker Hill (1982). Considering the themes and writing style of John Fante in the novels discussed here, we can relate them to the experience of the marginal writer in an unfavorable situation: a not very promising future in a country that is experiencing a recessionary economic scenario. Forged for the writing, Bandini is configured as a kind of author´s mirroring, a character in which Fante inserts himself through time and narrative within the scope of autobiographical writing.Os romances analisados têm como elo o personagem Arturo Bandini, considerado alter ego do escritor John Fante, cujo contexto é o da Grande Depressão americana: Wait Until Spring, Bandini (1938), The Road to Los Angeles (cronologicamente este é o primeiro romance da saga, mas foi publicado apenas postumamente, em 1985), Ask the Dust (1939) e Dreams from Bunker Hill (1982). Considerando as temáticas e o estilo de escrita de John Fante nos romances aqui discutidos, podemos relacioná-los à experiência do escritor marginal em um panorama nada favorável: um futuro pouco promissor em um país que amarga um cenário econômico recessivo. Forjado para a escrita, Bandini configura-se como uma espécie de espelhamento do autor, um personagem no qual Fante se insere através do tempo e da narrativa no âmbito da escrita de cunho autobiográfico
Neutron diffraction analysis of [H3Pt2(Ph2PCH2CH2PPh2)2]+[BPh4]-: An unusual example of an unsymmetrical [P2Pt(μ-H)2PtP2H] core [2]
No full textA Series of monohapto pyrazolates of iridium(I) and iridium(III)
No full textThe reaction of trans-IrCl(CO)L2 with pz-1 1 Throughout this paper, 1-unsubstituted pyrazole (C3H4N2) is indicated by PzH, while pzH indicates a generic pyrazole on which ring substituents may be present (e.g.3,5-Me2-4-NO2pzH is 3,5-dimethyl-4-nitropyrazole). gives trans-Ir(pz-N)(CO)L2, where pzH is 3,5-dimethyl-, 3,5-dimethyl-4-nitro- or 3,5-bis(trifluoromethyl)-pyrazole, and L = PPh3. The nitrogen atom not involved in coordination can be protonated with HBF4 to give the corresponding [Ir(CO)L2(pzH-N]+ cation. The iridium(I) pyrazolates undergo oxidative addition, yielding Ir(H)2(pz-N)(CO)L2 species, while gaseous HCl cleaves the IrN bond, affording IrH(Cl)2(CO)L2. The iridium(I) derivatives can be obtained in several solid-state forms, each characterized by a slightly different CO stretching frequency. The presence of a monodentate pyrazolato ligand in trans-Ir(3,5-(CF3)2pz-N)(CO)L2, in the form with ν(CO) at 1975 cm-1, is supported also by an X-ray crystal structure determination. The compound crystallizes in the monoclinic system, space group P21/n, with cell dimensions a = 21.106(6), b = 19.700(5), c = 9.437(2) Å, and β = 94.34(2)° and Z = 4. © 1984
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