Abstract
This paper reports on several new optically active organometallic [60]fullerene complexes that contain a chiral (+)‐DIOP or (−)‐DIOP ligand [DIOP = 2,3‐O,O′‐isopropylidene‐2,3‐dihydroxy‐1,4‐bis(diphenylphosphanyl)butane]. The Mo/W complexes mer‐[(η^2^‐C~60~)M(CO)~3~{(−)‐DIOP}] (1, M = Mo; 2, M = W) and mer‐[(η^2^‐C~60~)M(CO)~3~{(+)‐DIOP}] (3, M = Mo; 4, M = W) were synthesized by a photochemical reaction of a mixture of [M(CO)~6~], (−)‐DIOP or (+)‐DIOP and C~60~ in chlorobenzene in 42−51% yields, whereas the Pd/Pt complexes [(η^2^‐C~60~)M{(−)‐DIOP}] (5, M = Pd; 6, M = Pt) were prepared by a thermal reaction of C~60~ with [M(PPh~3~)~4~], followed by in situ treatment of the intermediate [(η^2^‐C~60~)M(PPh~3~)~2~] with (−)‐DIOP, in toluene in > 90% yields. All the new complexes 1−6 were fully characterized by elemental analysis, ^1^H (^31^P, ^13^C) NMR, IR, UV/Vis and circular dichroism (CD) spectroscopy. The structure of [(η^2^‐C~60~)Pt{(−)‐DIOP}] (6) was further confirmed by X‐ray diffraction techniques. The electrochemical properties of complexes 1, 2, 5 and 6 were studied in dichloromethane solution. Complexes 1 and 2 display the reversible, four‐membered, one‐electron reduction sequence typical of fullerene ligands, as well as the reversible (in the cyclic voltammetric time scale) one‐electron oxidation of the outer metal fragment. Complexes 5 and 6 are less stable to the same electron transfer processes. EPR measurements suggest that in the different electrogenerated monoanions, the added electrons enter the LUMO orbitals partially contributed by the metal fragment. In addition, they confirm that the instability of the reduction intermediates is due to the release of free C~60~. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)