General The making and breaking of carbon-metal bonds is fundamental to all the p- cesses of organometallic chemistry and moreover plays a significant role in - mogeneous as well as heterogeneous catalysis. This rather blunt statement - phasises the extent to which a proper understanding of the structure, energetics and reactivity of C-M bonds is at the core of the discipline. In order to accept it, a proper definition of the terms involved is required. Quite simply we define the metal-carbon bond in its broadest sense to embrace carbon linked to transiti- metals, lanthanides and actinides, and main group metals. We do not dist- guish between formally covalent single or multiple bonding on the one hand and q-bonding on the other. In the studies to be described in the following chapters, the emphasis will be on transition metal complexes and insofar as the fun- mentals come under scrutiny, simple metal alkyls or related species (metal al- nyl, alkynyl, aryl, or allyl) will play an emphatic part. The central role of metal alkyls and their congeners and especially the role of their metal carbon linkage in homogeneous catalysis may be appreciated by considering some key reaction steps leading to their formation or breakdown. There follows a few prominent examples of transition metal mediated stoichiometric or catalytic processes: - In homogeneous hydrogenation of double bonds, the stepwise reaction of an q2-coordinated alkene with dihydrogen gives first an alkyl metal hydride, and then the decoordinated alkane by elimination.

General The making and breaking of carbon-metal bonds is fundamental to all the p- cesses of organometallic chemistry and moreover plays a significant role in - mogeneous as well as heterogeneous catalysis. This rather blunt statement - phasises the extent to which a proper understanding of the structure, energetics and reactivity of C-M bonds is at the core of the discipline. In order to accept it, a proper definition of the terms involved is required. Quite simply we define the metal-carbon bond in its broadest sense to embrace carbon linked to transiti- metals, lanthanides and actinides, and main group metals. We do not dist- guish between formally covalent single or multiple bonding on the one hand and q-bonding on the other. In the studies to be described in the following chapters, the emphasis will be on transition metal complexes and insofar as the fun- mentals come under scrutiny, simple metal alkyls or related species (metal al- nyl, alkynyl, aryl, or allyl) will play an emphatic part. The central role of metal alkyls and their congeners and especially the role of their metal carbon linkage in homogeneous catalysis may be appreciated by considering some key reaction steps leading to their formation or breakdown. There follows a few prominent examples of transition metal mediated stoichiometric or catalytic processes: - In homogeneous hydrogenation of double bonds, the stepwise reaction of an q2-coordinated alkene with dihydrogen gives first an alkyl metal hydride, and then the decoordinated alkane by elimination.

Les activites motrices impliquent l'organisation et le controle des composantes du corps en mouvement. Cet ouvrage presente divers travaux portant sur la dynamique de coordination chez l'homme. La coordination intra-membre apparait comme tres stable au point que sous l'effet de contraintes elle ne change pas de patron de coordination. En revanche, la coordination inter-membre, entre les ceintures pelvienne et scapulaire, apparait plus flexible face a l'absence de participation des bras et de changement de mode de deplacement permettant une meilleure adaptation. Enfin, face aux consequences des effets lies a la gravitation, la coordination entre les quatre membres deux a deux montre que si les principes directionnel et musculaire sont verifies, ils ne peuvent expliquer l'absence de patron preferentiel lorsque les membres sont soumis de facon symetrique aux effets gravitationnels. La precision et la stabilite de la coordination apparaissent identiques voire ameliorees lorsque les muscles agonistes et antagonistes sont sollicites de facon symetrique. Cet ouvrage s'adresse a toute personne interessee par la dynamique de coordination et plus generalement par la motricite humaine."