Ligand exchange reactions of fac -(dihapto-[60]fullerene) (dihapto-1,2- bis -(diphenylphosphino)ethane tricarbonyl chromium(0)

Abstract

The complex fac-(η2-C60)(η2-dppe)Cr(CO)3 (dppe = 1,2-bis(diphenylphosphino)ethane and C60 = [60]fullerene) reacts with piperidine (pip) to produce fac-(η2-C60)(η1-pip)2Cr(CO)3. The reactions are first order with respect to [ fac-(η2-C60)(η2-dppe)Cr(CO)3] under flooding conditions where [pip] ≫ [ fac-(η2-C60)(η2-dppe)Cr(CO)3]. The pseudo-first order rate constant values (k obsd) are [pip]-dependent. Curved (upward) plots of k obsd versus [pip] and linear plots of k obsd versus [pip]2 indicate that the piperidine-assisted dppe displacement from fac-(η2-C60) (η2-dppe)Cr(CO)3 is second order with respect to [pip]. The proposed mechanism involves a [60]fullerene-stabilized intermediate.