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Papers by Miguel Angel Álvarez Flores

Research paper thumbnail of Spillover Effects on Homicides across Mexican Municipalities: A Spatial Regime Model Approach

Review of Regional Studies, 2014

This paper investigates the existence of spatial regimes of high violence levels across Mexican m... more This paper investigates the existence of spatial regimes of high violence levels across Mexican municipalities. Our approach consists of providing a framework to explicitly address spatial heterogeneity, which might suggest instability in the structural determinants of homicides. In this context, a distinction is made in relation to the regimes in municipalities within states with long-standing trafficking activities by comparing those municipalities that have been exposed to joint operations (operativos conjuntos) and those that were not exposed to the operations. Spatial econometric models were estimated for each regime to investigate possible spillover effects arising from the covariates. The results point to differences in regard to the significance, magnitude, and sign of the effects related to some variables according to each spatial regime’s specification. While the direct effects show that socioeconomic variables tend to play an important role in explaining the variation of ...

Research paper thumbnail of Influence of S-Aryl Groups in the Coordination and Reactivity of (nido-Thiocarborane)ruthenium Complexes

Organometallics, 1998

The reaction of [RuCl 2 (PPh 3) 3 ] and [NMe 4 ][7,8-(SPh) 2-7,8-C 2 B 9 H 10 ] in ethanol yields... more The reaction of [RuCl 2 (PPh 3) 3 ] and [NMe 4 ][7,8-(SPh) 2-7,8-C 2 B 9 H 10 ] in ethanol yields [RuCl-(7,8-(SPh) 2-7,8-C 2 B 9 H 10)(PPh 3) 2 ]‚CH 2 Cl 2 (1). The structure of 1 has been determined by crystallographic studies. The crystal contains the two isomers 1a and 1b in a ratio of ca. 3:1. In both isomers the metal has an octahedral geometry and the carborane ligand tricoordinates the Ru(II) center by means of S-Ru, B(11)-H-Ru, and B(2)-H-Ru bonds. Two PPh 3 groups and a chloride ligand fulfill the coordination sphere of the metal. The two isomers arise from two different dispositions of the [RuCl(PPh 3) 2 ] + fragment with regard to the carborane cluster. The preference for two agostic B-H-Ru bonds rather than a second S-Ru bond appears to be due to steric factors. The reaction of [RuCl 2 (PPh 3) 3 ] and the cesium or tetramethylammonium salts of [7-(SPh)-8-R-7,8-C 2 B 9 H 10 ]-(R) Me, Ph) yields [RuCl(7-SPh-8-R-7,8-C 2 B 9 H 10)(PPh 3) 2 ] (2, R) Me; 3, R) Ph). NMR spectroscopic analyses of 2 and 3 also indicate the presence of isomers analogous to those observed for 1. Unlike the S-alkylsubstituted (monothiocarborane)ruthenium complexes reported earlier, complexes 1-3 do not undergo B(5) elimination to form an arachno cluster. Complex 2 catalyzes the hydrogenation of 1-hexene, exhibiting a TON of 115 ([1-hexene]) 3.9 M, [2]) 5.21 × 10-4 M, 66°C, P) 45 bar, 1 h).

Research paper thumbnail of Spillover Effects on Homicides across Mexican Municipalities: A Spatial Regime Model Approach

Review of Regional Studies, 2014

This paper investigates the existence of spatial regimes of high violence levels across Mexican m... more This paper investigates the existence of spatial regimes of high violence levels across Mexican municipalities. Our approach consists of providing a framework to explicitly address spatial heterogeneity, which might suggest instability in the structural determinants of homicides. In this context, a distinction is made in relation to the regimes in municipalities within states with long-standing trafficking activities by comparing those municipalities that have been exposed to joint operations (operativos conjuntos) and those that were not exposed to the operations. Spatial econometric models were estimated for each regime to investigate possible spillover effects arising from the covariates. The results point to differences in regard to the significance, magnitude, and sign of the effects related to some variables according to each spatial regime’s specification. While the direct effects show that socioeconomic variables tend to play an important role in explaining the variation of ...

Research paper thumbnail of Influence of S-Aryl Groups in the Coordination and Reactivity of (nido-Thiocarborane)ruthenium Complexes

Organometallics, 1998

The reaction of [RuCl 2 (PPh 3) 3 ] and [NMe 4 ][7,8-(SPh) 2-7,8-C 2 B 9 H 10 ] in ethanol yields... more The reaction of [RuCl 2 (PPh 3) 3 ] and [NMe 4 ][7,8-(SPh) 2-7,8-C 2 B 9 H 10 ] in ethanol yields [RuCl-(7,8-(SPh) 2-7,8-C 2 B 9 H 10)(PPh 3) 2 ]‚CH 2 Cl 2 (1). The structure of 1 has been determined by crystallographic studies. The crystal contains the two isomers 1a and 1b in a ratio of ca. 3:1. In both isomers the metal has an octahedral geometry and the carborane ligand tricoordinates the Ru(II) center by means of S-Ru, B(11)-H-Ru, and B(2)-H-Ru bonds. Two PPh 3 groups and a chloride ligand fulfill the coordination sphere of the metal. The two isomers arise from two different dispositions of the [RuCl(PPh 3) 2 ] + fragment with regard to the carborane cluster. The preference for two agostic B-H-Ru bonds rather than a second S-Ru bond appears to be due to steric factors. The reaction of [RuCl 2 (PPh 3) 3 ] and the cesium or tetramethylammonium salts of [7-(SPh)-8-R-7,8-C 2 B 9 H 10 ]-(R) Me, Ph) yields [RuCl(7-SPh-8-R-7,8-C 2 B 9 H 10)(PPh 3) 2 ] (2, R) Me; 3, R) Ph). NMR spectroscopic analyses of 2 and 3 also indicate the presence of isomers analogous to those observed for 1. Unlike the S-alkylsubstituted (monothiocarborane)ruthenium complexes reported earlier, complexes 1-3 do not undergo B(5) elimination to form an arachno cluster. Complex 2 catalyzes the hydrogenation of 1-hexene, exhibiting a TON of 115 ([1-hexene]) 3.9 M, [2]) 5.21 × 10-4 M, 66°C, P) 45 bar, 1 h).