Finite element modelling of Tertiary paleostress fields in the eastern part of the Tajo Basin (Central Spain).

Three subsequent Tertiary paleostress fields that are deduced from fault-slip data for the eastern part of the Tajo Basin are analyzed by finite-element studies. The modelling results show that maximum horizontal stresses (SHmax) are mainly controlled by the geometry of the model limits and the boundary conditions applied. The models are used to test two hypotheses on the origin of the Altomira Range. A local stress field responsible for its formation (‘Altomira') can be modelled successfully by superposition in time and place of two major paleostress fields (‘Iberian' and ‘Guadarrama'). Stress trajectories have been modelled with respect to a homogeneous cover and heterogeneous basement to investigate the role of rheological contrasts between different basement blocks on the orientation of the stress field. Results of this kind of modelling suggest a mechanical decoupling between the cover and the basement, especially for the ‘Altomira' paleostress field

Chelated Assisted Metal-Mediated N–H Bond Activation of β‑Lactams: Preparation of Irida‑, Rhoda‑, Osma‑, and Ruthenatrinems

2-Azetidinones substituted with pyridine (<b>2a</b>), quinoline (<b>2b</b>), isoquinoline (<b>2c</b>), imidazole (<b>2d</b>), and benzimidazole (<b>2e</b>) at the 4-position of the four-membered ring have been prepared in order to synthesize tribactams containing a transition metal and its associated ligands, L_<i>n</i>M, at the 2-position of the tricyclic skeleton. The developed procedure is compatible with a wide range of transition-metal starting complexes. Thus, the iridium and rhodium dimers [M­(η⁵-C₅Me₅)­Cl₂]₂ react with <b>2a</b>–<b>e</b>, in the presence of sodium acetate, to afford irida- and rhodatrinems (<b>1a</b>–<b>j</b>) containing the half-sandwich d⁶ metal fragments M­(η⁵-C₅Me₅)Cl (M = Ir, Rh). The reactions of [M­(μ-OMe)­(η⁴-COD)]₂ (M = Ir, Rh) with <b>2a</b> lead to irida- and rhodatrinems (<b>1k</b>,<b>l</b>) with the d⁸ moieties M­(η⁴-COD). The coordination sphere and oxidation state of the metal center in these compounds can be modified, without affecting the 2-azetidinone backbone, by means of substitution and oxidative addition reactions. As a proof of concept, metallatrinems with the M­(CO)₂ (M = Ir (<b>1m</b>), Rh (<b>1n</b>)) and Ir­(Me)­I­(CO)₂ (<b>1o</b>) units are also reported. Osmatrinems <b>1p</b>,<b>q</b> containing the d⁴ metal fragment OsH₃(PⁱPr₃)₂ have been obtained starting from the d² hexahydride OsH₆(PⁱPr₃)₂, by reaction with <b>2a</b>,<b>b</b>, whereas the treatment of the tetrahydroborate complexes MH­(η²-H₂BH₂)­(CO)­(PⁱPr₃)₂ (M = Os, Ru) with <b>2a</b> yields osma- and ruthenatrinems (<b>1r</b>,<b>s</b>) containing six-coordinate bis­(phosphine) d⁶ metal fragments. The IR stretching frequency of the lactamic carbonyl, the bent angle between the five- and four-membered rings of the tricycle, and the N–CO bond length in the lactamic ring are clearly infuenced by the L_<i>n</i>M fragment