Alkene metathesis in transition metal coordination spheres: The quest for molecular gyroscopes


John A. Gladysz,, Institut für Organische Chemie, Universität Erlangen-Nürnberg, Henkestraße 42, Erlangen, 91054, Germany
Children never cease to be fascinated by toy gyroscopes, which commonly consist of (1) a rotating axis and disk, and (2) two to four static spokes that connect the termini of the axis. This talk will describe the syntheses of the first molecules that duplicate the connectivity, symmetry (Dnh), and rotational ability of such gyroscopes. Complexes with trans R3P-MLn-PR3 linkages are first prepared, with R groups that terminate with a CH=CH2 moiety. Then alkene metathesis is used to conduct a three-spoked cage molecule. The C=C units are hydrogenated to give gyroscope-like species. Yields are highest with rotators such as Fe(CO)3, which features a three-fold symmetry axis. However, reasonable yields can also be obtained with MLn = PdCl2 and Rh(CO)Cl. Rotational barriers and reactions of the MLn moieties will be described, together with collaborative experiments directed at effecting unidirectional rotation.