Memoria del II Coloquio Internacional sobre Diversidad Cultural y Estudios Regionales

Desde la Sede de Occidente y, específicamente, en el seno de la Coordinación de Investigación y con el apoyo de la Dirección de la Sede y las Coordinaciones de Docencia, Administración y Acción Social, así como de la Vicerrectoría de Investigación, se han celebrado en el 2011 y en el 2012 dos coloquios internacionales sobre diversidad cultural y estudios regionales. El propósito de ambos consistió principalmente en motivar a investigadores e investigadoras de las distintas unidades académicas de la Universidad de Costa Rica y de otras instituciones de Educación Superior, así como a representantes de Centros e Institutos de Investigación nacionales e internacionales, a presentar resultados de investigaciones que contribuyeran a un mayor conocimiento de los procesos culturales y que dieran a conocer resultados que permitieran la comprensión de las realidades de distintos sectores y regiones. En el 2011 se presentaron cuarenta y seis ponencias y se dictaron tres conferencias magistrales, y en el 2012 se expusieron cincuenta ponencias y se impartieron tres conferencias magistrales.UCR::Sedes Regionales::Sede de Occidente::Recinto San Ramón::Centro de Investigaciones sobre Diversidad Cultural y Estudios Regionales (CIDICER

Anales del III Congreso Internacional de Vivienda y Ciudad "Debate en torno a la nueva agenda urbana"

Acta de congresoEl III Congreso Internacional de Vivienda y Ciudad “Debates en torno a la NUEVa Agenda Urbana”, ha sido una apuesta de alto compromiso por acercar los debates centrales y urgentes que tensionan el pleno ejercicio del derecho a la ciudad. Para ello las instituciones organizadoras (INVIHAB –Instituto de Investigación de Vivienda y Hábitat y MGyDH-Maestría en Gestión y Desarrollo Habitacional-1), hemos convidado un espacio que se concretó con potencia en un debate transdisciplinario. Convocó a intelectuales de prestigio internacional, investigadores, académicos y gestores estatales, y en una metodología de innovación articuló las voces académicas con las de las organizaciones sociales y/o barriales en el Foro de las Organizaciones Sociales que tuvo su espacio propio para dar voz a quienes están trabajando en los desafíos para garantizar los derechos a la vivienda y los bienes urbanos en nuestras ciudades del Siglo XXI

Síntesis, caracterización estructural y actividad biológica de compuestos ciclometalados de paladio y platino con derivados de benzoilbencilideniminas

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química. Fecha de lectura: 30-10-199

Synthesis and Reactivity of Monocyclopentadienyl Tantalum Complexes with Pincer Dialkoxide Ligands

The new tantalum dialkoxide complexes Cp*TaCl2(OCH2)2py (1), trans-Cp*TaMe2(OCH2)2py (2), and cis-Cp*TaMe2(OCH2)2py (3) (Cp* = η5-C5Me5; (OCH2)2py = 2,6-pyridinedimethoxide) have been synthesized. The molecular structures of complexes 1 and 2 have been studied by X-ray diffraction methods. The reaction of complex 3 with carbon monoxide renders Cp*Ta(η2-Me2CO)(OCH2)2py (4), while with isocyanides yields the respective azatantalacyclopropanes Cp*Ta(η2-Me2CNxylyl)(OCH2)2py (6) (xylyl = 2,6-dimethylphenyl) and Cp*Ta(η2-Me2CNtBu)(OCH2)2py (7). The molecular structure of complex 4 has been established by X-ray diffraction. The coordinated ketone in 4 can be reduced to 2-propanol in the presence of water. On the other hand, compound 3 reacts with triflic acid (HOTf) to render the corresponding cationic derivative [Cp*TaMe(OCH2)2py]OTf (8).We gratefully acknowledge financial support from Ministerio de Educación y Ciencia, Spain (Grant No. BQU2002-04638), and the Junta de Comunidades de Castilla-La Mancha (PAC-02-003 and GC-02-010).Peer reviewe

Preparation, characterization, and reactivity of tantalum complexes containing tridentate bis(phenolato) [OSO]-type ligands

A series of new tantalum-tbcp [tbcp = 2,2′-thiobis(4,6-dichlorophenolato)] and tantalum-tbop [tbop = 2,2′-thiobis(6-tert-octylphenolato)] complexes [TaCp*Cl2(κ3-tbop)] (1), [TaCp*Cl2(κ3-tbcp)] (2), [TaCp*Me2(κ3-tbop)] (3), [TaCp*Me2(κ3-tbcp)] (4), [TaCp*Me(κ3-tbop)(OTf)] (OTf = triflate) (5), [TaCp*Me(κ3-tbcp)(OTf)] (6), [TaCp*(κ3-tbop)(OTf)2] (7), and [TaCp*(κ3-tbcp)(OTf)2] (8) have been synthesized. Insertion processes into the methyl groups of complex 3 were not observed upon reaction with CO or isocyanides. In contrast, complex 4 reacted slowly with 1 equiv of xylyl isocyanide (xylyl = 2,6-dimethylphenyl) or tert-butyl isocyanide to yield complexes [TaCp*(κ2-Me2CNxylyl)(κ3-tbcp)] (9) and [TaCp*Me(κ2- MeCNtBu)(κ3-tbcp)] (10), respectively. All products were characterized by NMR spectroscopy and elemental analysis. The single-crystal structures of 2, 3, 6, and 9 were also determined.We gratefully acknowledge the Ministerio de Ciencia e Innovación, Spain, for financial support (Grant Nos. CTQ2005-08123-CO2-01/BQU, CTQ2006-11845/BQU, Consolider Ingenio 2010 ORFEO CSD-2007-00006) and also for a fellowship (J.F.-G., Grant No. AP2005-4738) and the Junta de Comunidades de Castilla-La Mancha, Spain (Grant No. PBI05-029)

Lewis base character of the phosphorus atom in phosphanido-niobocene complexes. Synthesis of new early-early homo- and heterobimetallic entities

The reaction of phosphanido complexes [Nb(eta(5)-C(5)H(4)SiMe(3))2(L)(PPh(2))] [L = CO (1), CNXylyl (2)] with early transition metal halides in high oxidation states has been carried out. New bimetallic niobocene complexes [{Nb(eta(5)-C(5)H(4)SiMe(3))(2)(L)}(mu-PPh(2))(MCl(5))] [M = Nb, L = CO (3), L = CNXylyl (4); M = Ta, L = CO (5), L = CNXylyl (6)] have been successfully synthesized by the reaction with [MCl(5)](2) (M = Nb or Ta). In a similar way [{Nb(eta(5)-C(5)H(4)SiMe(3))(2)(L)}(mu-PPh(2))(MCl(4))] [M = Ti, L = CO (13), CNXylyl (14); M = Zr, L = CO (15), CNXylyl (16)] were synthesized using MCl(4) (M = Ti or Zr). Solutions of complexes 4-6 in chloroform produced new ionic derivatives [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(P(H)Ph(2))(L)] [MCl(6)] [M = Nb, L = CO (7), L = CNXylyl (8); M = Ta, L = CO (9), L = CNXylyl (10)]. Ionic complexes [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(P(Cl)Ph(2))(L)] [NbCl(4)O(thf)] [L = CO (11), CNXylyl (12)] were formed from solutions in thf - rapidly in the case of 3 but more slowly for 4. New heterometallic complexes [Nb(eta(5)-C(5)H(4)SiMe(3))(2)(L)(mu-PPh(2)){(Ti(eta(5)-C(5)R(5))Cl(3)}] [R = H, L = CO (17), CNXylyl (18); R = CH(3), L = CO (19), CNXylyl (20)] were synthesized by the reaction of 1 or 2 with [Ti(eta(5)-C(5)R(5))Cl(3)] (R = H or CH(3)). All of these compounds were characterized by IR and multinuclear NMR spectroscopy, and the molecular structures of 9 and 12 were determined by single-crystal X-ray diffraction

Simple, versatile, and efficient catalysts for guanylation of amines

Commercially available products such as ZnEt2 (1), MgBu2 (2), and n-BuLi (3) can act as excellent catalytic precursors for the catalytic addition of amines to carbodiimides. Aromatic primary amines bearing different substituents, secondary amines, and heterocyclic amines can undergo this reaction. The synthesis and structural characterization of the zinc guanidinate complex [Zn(Et){(4-t-BuC6H4)N═C(N-i-Pr)(NH-i-Pr)}]2 (15) and the synthesis and characterization of the lithium guanidinate complex [Li{(2,4,6-Me3C6H4)N═C(N-i-Pr)(NH-i-Pr)}(THF)] (16), both of which act as catalysts in the guanylation reaction, allowed us to propose a mechanism involving the formation of amido intermediates. These amido compounds subsequently react with the carbodiimide in an insertion process.Peer reviewe

Synthesis, structure and reactivity of new late transition metal complexes bearing diphosphane ligands derived from bis(pyrazol-1-yl)methane

Modification of the multistep synthesis of the previously described bis[5-(diphenylphosphanyl)pyrazol-1-yl)]methane (bppzm, 1) produces the novel diphosphane (diphenylphosphanyl)-[5-(diphenylphosphanyl)pyrazol-1-yl](pyrazol-1-yl)methane (p4m, 2). Treatment of this ligand with [MCl2(PhCN)2] (M = Pd, Pt) or [M(COD)(THF)2]BF4 (M = Rh, Ir) produces [MCl2(p4m)] (M = Pd 3, Pt 4) or [M(COD)(p4m)]BF4 (M = Rh 5, Ir 6) complexes, which chelate in a P,P-bidentate fashion. Sulfidation of bppzm and p4m produces the disulfidophosphanes bppzmS2 (7) and p4mS2 (8). Treatment of 7 and 8 with [PdCl2(PhCN)2] produces [PdCl2(bppzmS2)] (9) and [PdCl2(pmS2)] (10), respectively, in which ligands 7 and 8 act in an N,N-bidentate chelate fashion. In contrast, ligand 8 reacts with [Rh(COD)(THF)2]BF4 to produce [Rh(COD)(p4mS2)]BF4, where ligand 7 acts in a dynamic S,S-chelate fashion. The activity of some of these complexes in the catalytic hydrogenation of olefins is reported and the single-crystal X-ray structures of 4, 8, and 9 have been obtained.We gratefully acknowledge financial support from the Dirección General de Enseñanza Superior e Investigación Científica (Ministerio de Educación y Cultura), Spain (Grant. No. 1FD97−0176)

Theoretical, dynamic, and structural studies of the phenyl rotation in bispentafluorophenyl palladium complexes with scorpion-type ligands

A theoretical study at a DFT level has been carried out on the pentafluorophenyl rotation in the compounds [Pd(C6F5)2(bpzmPh)] (1) and [Pd(C6F5)2(bpz*mPh)] (2) (bpzm = bis(pyrazol-1-yl)phenylmethane and bpz*mPh = bis(3,5-dimethylpyrazol-1-yl)phenylmethane). The orientation of one C6F5 with respect to the coordination plane was forced to adopt specific values to simulate ring rotation and several parameters, such as the disposition of the other C6F5 group, the energy of the system, and the skeletal conformation of the bpz'm ligand, were analysed. The maximum energy value was found when the C6F5 ring was nearly coplanar with the coordination plane. In both complexes the minimum energy corresponds to a situation where the two rings are nearly parallel. A number of distortions that mainly affect the NPdN bite angle were predicted for the complex containing the bpz*mPh ligand (methylated pyrazoles). Four structures of complexes from this family were determined by X-ray diffraction and the same types of distortion were found. The differences in the free energies of activation for the pentafluorophenyl rotation in complexes containing methylated and non-methylated ligands were theoretically calculated. The calculated values were consistent with the data experimentally determined by NMR spectroscopy. The origin of the difference was attributed to the aforementioned distortions of the complexes containing the bpz*mPh ligand, which were more remarkable in the configuration of maximum energy.Peer reviewe