046ChemInform Abstract The degenerate interconversions of the two enantiomeric forms of the agostic title complexes (M: Co; R: H, Me) via the sym. terminal hydrides (C5R5)Co(C2H4)2H+ are investigated by 13C NMR spectroscopy at 100.6 MHz in the temp. range -80 to -100 rc C. The determined free energies of activation for this process (5.3 kcal/mol) represent a maximum energy difference between the agostic and terminal hydride structures. The barrier for degenerate isomerization of the agostic Rh title complex (M: Rh; R: Me) via the terminal hydride is < 3.7 kcal/mol. Since complexes of the type (C5R5)(L)Rh(C2H4)H+ (L: PR3, P(OR)3) are terminal hydrides, these Rh systems represent a unique case where agostic and terminal hydride structures are sufficiently close in energy that the stable form observed can be altered by small change in the ancillary ligand.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.