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31.
Aguirre PA Lagos CA Moya SA Zúñiga C Vera-Oyarce C Sola E Peris G Bayón JC 《Dalton transactions (Cambridge, England : 2003)》2007,(46):5419-5426
The methoxycarbonylation of alkenes catalyzed by palladium(II) complexes with P,N-donor ligands, 2-(diphenylphosphinoamino)pyridine (Ph2PNHpy), 2-[(diphenylphosphino)methyl]pyridine (Ph2PCH2py), and 2-(diphenylphosphino)quinoline (Ph2Pqn) has been investigated. The results show that the complex [PdCl(PPh3)(Ph2PNHpy)]Cl or an equimolar mixture of [PdCl2(Ph2PNHpy)] and PPh3, in the presence of p-toluensulfonic acid (TsOH), is an efficient catalyst for this reaction. This catalytic system promotes the conversion of styrene into methyl 2-phenylpropanoate and methyl 3-phenylpropanoate with nearly complete chemoselectivity, 98% regioselectivity in the branched isomer, and high turnover frequency, even at alkene/Pd molar ratios of 1000. Best results were obtained in toluene-MeOH (3 : 1) solvent. The Pd/Ph2PNHpy catalyst is also efficient in the methoxycarbonylation of cyclohexene and 1-hexene, although with lower rates than with styrene. Related palladium complexes [PdCl(PPh3)L]Cl (L = Ph2PCH2py and Ph2Pqn) show lower activity in the methoxycarbonylation of styrene than that of the 2-(diphenylphosphinoamino)pyridine ligand. Replacement of the last ligand by (diphenylphosphino)phenylamine (Ph2PNHPh) or 2-(diphenylphosphinoaminomethyl)pyridine (Ph2PNMepy) also reduces significantly the activity of the catalyst, indicating that both the presence of the pyridine fragment as well as the NH group, are required to achieve a high performing catalyst. Isotopic labeling experiments using MeOD are consistent with a hydride mechanism for the [PdCl(PPh3)(Ph2PNHpy)]Cl catalyst. 相似文献
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Karla-Alejandra Lpez-Gastlum Enrique F. Velzquez-Contreras Juventino J. García Marcos Flores-Alamo Gerardo Aguirre Daniel Chvez-Velasco Jayanthi Narayanan Fernando Rocha-Alonzo 《Molecules (Basel, Switzerland)》2021,26(23)
Two new glycine-Schiff base copper(II) complexes were synthesized. Single crystal X-ray diffraction (SCXRD) allowed us to establish the structure of both complexes in the solid state. The glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-nitroacetophenone showed a mononuclear hydrated structure, in which the Schiff base acted as a tridentate ligand, and the glycine-Schiff base copper(II) complex derived from 2′-hydroxy-5′-methylacetophenone showed a less common tetranuclear anhydrous metallocyclic structure, in which the Schiff base acted as a tetradentate ligand. In both compounds, copper(II) had a tetracoordinated square planar geometry. The results of vibrational, electronic, and paramagnetic spectroscopies, as well as thermal analysis, were consistent with the crystal structures. Both complexes were evaluated as catalysts in the olefin cyclopropanation by carbene transference, and both led to very high diastereoselectivity (greater than 98%). 相似文献
35.
Inigo Aguirre de Carcer 《Journal of organometallic chemistry》2009,694(6):840-791
The sulfur-rich iron carbonyl dimer complexes [Fe(CO)2(S′SiS2)]2 (2), and [Fe(CO)(S′SiS2)]2 (3) have been prepared. The [2Fe-2S] cores of the new complexes are planar. The binding mode of the tridentate sulfur ligand in complex 2 is facial with a S(thiolate)-Fe-S(thiolate) angle of 92°, while in complex 3, the S′SiS2 ligand binds the metal with a S(thiolate)-M-S(thiolate) angle of 120°. The Fe-Fe distance is reduced from 3.45 Å in complex 2 to 2.78 Å in the 32 electron dimer complex 3. Complexes 2 and 3 are at equilibrium in solution and can be readily interconverted by addition or removal of CO. 相似文献
36.
Pedro Aguirre Kareen Brown Diego Venegas-Yazigi Verónica Paredes-García Evgenia Spodine 《Macromolecular Symposia》2011,304(1):65-71
Summary: The search of new inorganic materials with better catalytic properties is an important field of research. Reusability, efficiency and atom economy correspond to the main parameters to characterize a catalyst. In this work, we inform the effectiveness of [Cu(H2btec)(bipy)]∞ (H4btec = 1,2,4,5-benzenetetracarboxylic acid) as an heterogeneous coordination polymer catalyst for the oxidation of olefins. The catalyst exhibits good atom economy, high turnover numbers and good selectivity for a ratio of 4000/1 substrate/catalyst for cyclohexene and styrene oxidation. Furthermore, the catalyst was recycled and reused for seven consecutive cycles, retaining the structural integrity and effectiveness as catalyst in all the performed experiments. 相似文献
37.
Aguirre de Carcer I DiPasquale A Rheingold AL Heinekey DM 《Inorganic chemistry》2006,45(20):8000-8002
Reduction of Fe2(mu-S2C3H6)(CO)6 (1) in tetrahydrofuran with 1 equiv of decamethylcobaltocene (Cp*2Co) affords a tetranuclear dianion 2. The IR spectra of samples of 2 in solution and in the solid state exhibit a band at 1736 cm(-1), suggestive of the presence of a bridging carbonyl (CO) ligand. X-ray crystallography confirms that the structure of 2 consists of two Fe2 units bridged by a propanedithiolate moiety formulated as [Fe2(mu-S2C3H6)(CO)5(SCH2CH2CH2-mu-S)Fe2(mu-CO)(CO)6](2-). One of the Fe2 units has a bridging CO ligand and six terminal CO ligands. The second subunit exhibits a bridging propanedithiolate moiety. One CO ligand has been replaced by a terminal thiolate ligand, replicating the basic architecture of Fe-only hydrogenases. The reduction reaction can be reversed by treatment of 2 with 2 equiv of [Cp2Fe][PF6], reforming complex 1 in near-quantitative yield. Complex 2 can also be oxidized by acids such as p-toluenesulfonic acid, regenerating complex 1 and forming H2. 相似文献
38.
Manuel Aguirre Téllez Rubén Alejandro Cerutti Susana Elena Trione 《Acta Appl Math》1997,48(3):235-284
The present note contains the Tables of Fourier, Laplace and Hankel transforms of several dimensional generalized functions. They are, mainly, based on the Laplace transform of retarded, Lorentz-invariant functions and the Fourier transforms of causal distributions. 相似文献
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C2-symmetric bis(sulfonamide) ligands derived from trans-(1R,2R)-cyclohexane-1,2-diamine were synthesized and complexed with [Cp∗RhCl2]2 in situ and used in the ATH of aromatic ketones with aqueous sodium formate as the hydrogen source. The chiral secondary alcohols were obtained with 90-99% enantioselectivity and in 50-100% yield. Reductions in water were faster than those in isopropanol/KOH. 相似文献