1,721,054 research outputs found
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
Binuclear hydride platinum(II) complexes: syntheses of [{Pt(P-P)}(2)(mu-CHCH2R)(mu-H)][BF4] (R = C6H5, H) and easy cleavage of a P-C bond in a chelating 1,4-bis (diphenyl)phosphinobutane (P-P)
No full textReactions of the binuclear platinum(II) trihydrido complex. [Pt-2{(Ph2P)(2)(CH2)(4)}(2)(H)(3)][BF4], with styrene or ethylene, at room temperature and low pressure, give mu-alkylidene, mu-hydrido cationic species [Pt-2{(Ph2P)(2)(CH2)(4)}(2)(mu-CHCH2R)(mu-H)][BF4] (R = C6H5, 1; H, 2) together with an unexpected phosphido-bridged binuclear platinum(II) compound (3), originating from cleavage of a P-C bond in the coordinated diphosphine. Complexes 1-3 are discussed on the basis of FAB MS, IR and multinuclear NMR spectra in solution. (C) 2000 Elsevier Science S.A. All rights reserved
Auraoxetanes as Plausible Intermediates in the Oxidation of Alkenes by Oxygen- Transfer Reaction from Gold(III) Oxo Complexes.
No full textAlkene oxidation by oxygen atom transfer reaction from late transition metal oxo complexes is, at present, an objective of particular interest. Metallaoxetanes, proposed as possible intermediates, have been recently isolated in the case of platinum(II).1 Intermediacy of metallaoxetanes in metal catalyzed alkene epoxidations has been proven in the case of silver as well.2
A series of gold(III) oxo complexes, [Au2(N,N)2(μ-O)2][PF6]2, supported by bidentate 6-substituted-2,2’- bipyridines, had been synthesized several years ago by some of us.3 Preliminary studies, indicating the feasibility of oxygen atom transfer reaction, were followed by extensive investigations on the alkene oxidation. The reaction with styrene, chosen as a model, was thoroughly studied and a gold(I) olefin complex [Au(N,N)(η2-CH2=CHPh][PF6] structurally characterised.4 Styrene oxygenated derivatives, contemporaneously formed, were identified as well. Analogous results have been successively obtained with other terminal olefins, while no reaction takes place with internal olefins. Following the hypothesis that gold(I) alkene complexes and alkene oxidation products could have been originated by a common precursor, and that the precursor was likely to be an auraoxacyclobutane, we thought to study the reaction with strained cyclic olefins, such as 2-norbornylene, nb, and 2,5-norbornadiene, nbd. These olefins, being rather reactive but lacking of active β-hydrogens, were good candidates for stabilizing a possible metallaoxetane intermediate. The reaction with both olefins proceeds slowly to give the gold(I) alkene complexes [Au2(N,N)2(μ-η4-nbd][PF6]2 and [Au(N,N)(η2-nb][PF6]2, respectively, as the main products. A second product of the reaction with nb, which depending on the substituent in 6 of the bipyridine and on the preparative conditions forms in appreciable amount, resulted to be an unprecedented auraoxetane [Au(bipyMe)(κ2-O,C-2- oxynorbornyl)][PF6].5 Plausible reaction pathways for the formation of the gold complexes and the oxygenated organic derivatives will be discussed.
References
[1] E. Szuromi, H. Shan, P.R. Sharp, J. Am. Chem. Soc. 2003, 125, 10522-10523;
[2] S. Linic, H. Piao, K. Adib, M.A. Barteau, Angew. Chem. Int. Ed. 2004, 43, 2918-2921.
[3] M.A. Cinellu, G. Minghetti, M.V. Pinna, S. Stoccoro, A. Zucca, M. Manassero, M. Sansoni, J. Chem. Soc., Dalton Trans. 1998,
1735-1741.
[4] M.A. Cinellu, G. Minghetti, S. Stoccoro, A. Zucca and M. Manassero, Chem. Commun., 2004, 1618-1619 [5] M.A. Cinellu, G. Minghetti, F. Cocco, S. Stoccoro, A. Zucca, M. Manassero, submitted
SOME GOLD(III) DERIVATIVES OF PYRAZOLES
No full textVarious gold(III) derivatives of pyrazoles, pzH, were obtained and characterized. Besides the salt [3,5-Ph2pzH2][AuCl4], they included adducts, AuCl3·pzH, μ-pyrazolato-N,N′-derivatives, [Cl2Au(pz)]n (such as: n = 2 and pz = 3,5-diphenyl-4-chloropyrazolato), and one derivative containing both a neutral pyrazole and a pyrazolato ligand, Cl2Au(3,5-Ph2pz-N)(3,5-Ph2pzH)
SYNTHESIS AND STRUCTURE OF [PT2(MU-H)(MU-CHCH2PH)(DIPHOS)2][BF4]
No full textThe first compound in which a hydride- and an alkylidene-ligand bridge two Pt-atoms is present in the complex cation 2, which is formed on reaction of the complex 1 with styrene. 2 was characterized NMR spectroscopically and by an X-ray structure analysis. the Pt[BOND]Pt distance of 2.735(1) Å indicates that there is bonding interaction between the two metal atoms
NMR-STUDY OF THE CHEMICAL-EXCHANGE OF THE HYDRIDO LIGANDS IN THE BIS(BIS(DIPHENYLPHOSPHINO)ETHANE)TRIHYDRIDODIPLATINUM(II) CATION BY T1, T2, AND HD ISOTOPIC PERTURBATION
No full textProton longitudinal and transverse relaxation rates of hydrido resonances of different isotopomers in [H3Pt2(Dpe)2][BF4] [Dpe = bis(diphenylphosphino)ethane] show significant differences in the satellite peaks with respect to the central ones that can be used to evaluate the activation energy of the intramolecular exchange process and the chemical shift separation between bridging and terminal sites. An alternative route to get an estimation of the chemical shift values of the bridging and terminal hydrides in this derivative has been pursued by considering the isotopic shift of the three H-3, H2D, and HD2 isotopomers at different temperatures
An Investigation on Various Bis (N-substituted-imino)(alkoxy)methyl platinum(II) Derivatives as Ligands Towards Group IIB Halides and Rhodium Dicarbonyl Chloride
No full textThe adducts A.ZaBr2, B.2nBr2, A.CdI2, A.CdBr2, C.CdI2, B.CdI2, C.HgCI2, C.2HgCl2, D.HgCI2, A.Rh(CO)2Cl were prepared from the corresponding halide and the ligand A, (Ph3P)(ArNC)Pt-[c(OMe)=NAr]2 B, (DFE)Pt{c(OMe)=NAr]2, C, (DPE)Pt-[c(OMe)=NMe]2or D, (DPE)Pt-|c(OMe)=NCgH112(Ar= p-tolyl, DPE= 1,2-bis(diphenylphosphino) ethane). These platinum(II) bidentate ligands are basic since they can be proton at ed at the two imino nitrogens, which are likely to be the donor sites in the adducts
FAST ATOM BOMBARDMENT INDUCED DECOMPOSITION PATTERN OF THE GOLD(III) BIS(CARBENE) COMPLEX [((PARA-MEC6H4NH)(ETO)C)2AUI2]CIO4, A RETROSYNTHETIC PROCESS
No full textThe fast atom bombardment (FAB) induced decomposition pattern of the ionic bis(carbene)gold(HI) complex [{(P-MeC6H4NH)(EtO)C}2AuI2]ClO 4 (1) is described and discussed in detail with the aid of metastable data. A lack of [M]+ ions is observed when sulfolane is used as the matrix. Instead, the molecular species observed is the [M - H]•+ ion. The fragmentation pattern can be considered as a retrosynthetic process of the compound itself, never previously observed for an organometallic under FAB conditions. The MS pattern suggests the synthesis of the new carbene-methanide derivative 2, [{(p-MeC6H4NH)-(EtO)C}{(p-MeC6H 4N=)(EtO)C}Au], observed under FAB-MS conditions as the most stable ion. An independent synthesis was successful
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