Übergangsmetall-Methylen-Komplexe, VI [1] Zur irreversiblen µ-Methylen/Carbonyl-Isomerie zweikerniger Cobalt-Komplexe mit bifunktionellen Methylen-Liganden / Transition Metal Methylene Complexes, VI [1] On the Irreversible µ-Methylene/Carbonyl Isomerization of Binuclear Cobalt Complexes with Bifunctional Methylene Ligands

Abstract

Abstract Ethyl diazoacetate (2 a) and tert-butyl diazoacetate (2 b) are converted into the metal stabilized, doubly bridging alkoxycarbonyl carbenes upon photolysis with (ƞ5-C5H5)Co(CO)2 (1) in tetrahydrofurane at -110°C. Although the yields of µ-dicarbonyl-µ-ethoxycarbonylmethylene- bis(ƞ5-cyclopentadienylcobalt) (3 a) and the corresponding ieri-butyl derivative (3b) are low, both compounds attract considerable attention due to an unexpected and hitherto unknown irreversible carbonyl bridge opening process with concomitant µ-methylene rearrangement. These isomerizations have been established by IR and 1H NMR methods to be first order intramolecular processes.