José Antonio Chamizo

Synthesis and structure of nickel(II) and palladium(II) carbene complexes containing the 1,3-diallylimidazolidin-2-ylidene ligand

Trans-carbene complexes of nickel(II) and palladium(II) with 1,3-diallylimidazolidin-2-ylidene (LAllyl) were prepared and characterized by i.r., n.m.r. and mass spectra. The structure of two complexes were determined by single crystal X-ray diffraction techniques.

Filosofía de la química: I. Sobre el método y los modelos

Abstract Considering the difficulties identified by the philosophers of science to the universal and unique scientific method, the method of the chemistry is characterized with the analysis and the synthesis. Through same it is possible to explain the exponential growth of the chemical information in the last years.

PREPARATION AND ELECTROCHEMISTRY OF THIOLATE-PHOSPHINE COMPLEXES OF OSMIUM

Abstract —The paramagnetic, octrahedral complexes [Os(SC 6 F 5 ) 2 (O 2 CR)(PMe 2 Ph) 2 ] (R = C 6 F 5 , 1; C 6 H 4 CF 3 -2, 2; C 6 H 4 CF 3 -3, 3; C 6 H 4 CF 3 -4, 4; C 6 H 4 F-2, 5; C 6 H 4 F-3, 6; C 6 H 4 F-4, 7 ; CH 3 , 8 ; CF 3 , 9) have been prepared by treatment of the penta-coordinated complex [Os(SC 6 F 5 ) 3 (PMe 2 Ph) 2 ] with the corresponding fluoro-carboxylic acid. The diamagnetic, pentacoordinate, osmium(IV) complexes [OsX(SR) 3 (PR 3 1 )] [X = Cl, Br or SR; R = C 6 F 4 H-4 or C 6 F 5 ; PR 3 1 = PMe 2 Ph, PPh 3 , P(C 6 H 4 Y-4) 3 (Y = F, OMe, CF 3 , Me or Cl)] (10–14, 18, 20–23), show two successive one-electron reductions. Electrochemical data are also given for [Os(SC 6 F 5 ) 3 (PMe 2 Ph) 2 ] (19).

The scientific impact of mexican steroid research 1935-1965: A bibliometric and historiographic analysis

We studied steroid research from 1935 to 1965 that led to the discovery of the contraceptive pill and cortisone. Bibliometric and patent file searches indicate that the Syntex industrial laboratory located in Mexico and the Universidad Nacional Autónoma de México (UNAM) produced about 54% of the relevant papers published in mainstream journals, which in turn generated over 80% of the citations and in the case of Syntex, all industrial patents in the field between 1950 and 1965. This course of events, which was unprecedented at that time in a developing country, was interrupted when Syntex moved its research division to the US, leaving Mexico with a small but productive research group in the chemistry of natural products.

Thiolate complexes of osmium(IV): preparation of [Os(SR)4(PR′3)](R = C6F5, C6F4H-4, C6H4F-4 or Ph, R′= Ph; R = C6F5 or C6F4H-4, R′3= Me2Ph) and [OsCl(SC6F5)2(SC6H4X-3)(PMe2Ph)](X = F or CF3): crystal structures of [Os(SC6F4H-4)4(PPh3)] and [OsCl(SC6F5)2(SC6H4CF3-3)(PMe2Ph)]

The diamagnetic osmium(IV) complexes [Os(SR)4(PR′3)](R = C6F5, C6F4H-4, C6H4F-4, or Ph, R′= Ph; R = C6F5 or C6F4H-4, R′3= Me2Ph) and [OsCl(SC6F5)2(SC6H4X-3)(PMe2Ph)](X = F or CF3) have been prepared. The complex [Os(SC6F4H-4)4(PPh3)] has an essentially trigonal-bipyramidal structure with an apical PPh3 group [Os–P 2.391 (5), Os–Sap 2.414(5), mean Os–Seq, 2.207(7)A]. The structure of [OsCl(SC6F5)2(SC6H4CF3-3)(PMe2Ph)] is a somewhat distorted triagonal bipyramid with apical Cl– and PMe2Ph groups [Os–Cl 2.420(2), Os–P 2.340(2), mean Os–SC6F5 2.206(2), Os–SC6H4CF32.187(2)A]. The spectroscopic properties of these compounds are reported and the possibility of isomerism in solution is discussed.

Historical Teaching of Atomic and Molecular Structure

Besides the presentation and conclusions, the chapter is divided into two equally important sections. The first one describes the modern development of atomic and molecular structure, emphasising some of the philosophical problems that have been taken, and those that have to be faced in its understanding. The second discusses the alternative conceptions and difficulties of students of different educational levels and also the different approaches to its historical or philosophical teaching. Finally, we recognise the necessity for science teachers to assume a specific historical-philosophical position.

Estructura de la materia: de saberes y pensares

En este articulo se describe una forma distinta de ensenar, a nivel universitario, algunos temas relacionados con la estructura atomica y molecular de la materia. El enfoque tradicional se base en describir lo que sabemos de las propiedades y caracteristicas de los atomos y las moleculas. En este articulo proponemos una mayor aproximacion al estudio de la estructura de la materia basado en el como utilizar modelos sub-microscopicos de la materia para resolver problemas relevantes. Se presenta, ademas un ejemplo concreto de esta aproximacion curricular.

La naturaleza de la química

A partir de una reflexion historica sobre las particularidades de la quimica, que la diferencian de las otras ciencias, se realizo un primer estudio sobre la naturaleza de la quimica. Estudiantes de licenciatura de diversas carreras relacionadas con la quimica contestaron un cuestionario que busca reconocer, en que medida, son capaces de reconocer estas diferencias.

The History and Philosophy of Science and Their Relationship to the Teaching of Sciences in Mexico

Science is one of the main attributes of the contemporary world and, more than any other human activity, characterizes the current period from previous centuries. Great advances in the field of science and technology deeply influence natural and social processes. There has been a worldwide recognition of the role of science in modern societies, along with an urgent need to move towards more and better scientific education, particularly in developing countries. It becomes fundamental to modify the current education system regarding science and technology in countries like Mexico, where a cornerstone has been the inclusion of the reflections that historical and philosophical studies have produced in the last three decades.

Sobre la evaluación docente

Las universidades requieren una reflexion profunda sobre sus metas primordiales para construir una cultura de la evaluacion de la actividad de ensenanza, la cual es diferente de la de investigacion. La idea principal es que el proceso de evaluacion sumativa, burocratico, superficial y cerrado, sea transformado en uno que involucre a los profesores y sea y abierto.