Synthesis and Characterization of Ir(H)(CO)(PEt3})2(η2-C60)

Abstract

The title complex, Ir(H)(CO)(PEt3)2(η 2 -C 60 ) (2), has been prepared by the reaction of excess C 60 (4 equiv) with a tetrairidium complex Ir 4 (CO) 8 (PEt 3 ) 4 (1) in refluxing chlorobenzene in 40% yield as green crystals. Compound 2 has been characterized by cyclic voltammetry (CV), spectroscopic methods (mass, IR, 1 H and 31 P NMR), and a single crystal X-ray diffraction study. The molecular structure reveals that the iridium atom of 2 is coordinated by two axial ligands of a hydrogen atom and a carbonyl group, and three equatorial ligands of two phosphorus atoms and an η 2 -C 60 moiety. The CV study exhibits three reversible one-electron redox waves for the successive reductions of 2, together with additional four redox waves due to free C 60 reductions, which was formed by decomposition of 2 in the reduced states. The three reversible redox waves of 2 are shifted to more negative potentials by ca. 270 mV compared to free C 60 , reflecting both metal-to-C 60 π-back-donation and the electron-donating nature of the two phosphorus ligands.