W(CO)3(Ph2PC2H4PPh2)(η(2)-Sc3N@Ih-C80/Sc3N@D5h-C80): regioselective synthesis and crystallographic characterization of air-stable mononuclear complexes of endohedral fullerenes.

Abstract

The organometallic chemistry of endohedral metallofullerenes has lagged far behind that of empty fullerenes. Herein, we report a highly regioselective coordination reaction involving two Sc3N@C80 isomers and W(CO)4(Ph2PC2H4PPh2) (1), which affords only one mononuclear complex for each Sc3N@C80 isomer (2a for Sc3N@Ih-C80 and 2b for Sc3N@D5h-C80). X-ray results demonstrate that the tungsten center coordinates with the cages in an η(2) fashion on a [6,6]-bond in both cases, forming the first derivatives with a closed three membered ring for Sc3N@C80. Although IR and absorption spectroscopic results reveal relatively weak exohedral-metal to ligand π back-donation in both 2a and 2b, they show remarkable air-stability which promises their potential uses in related fields. Moreover, the coordination has narrowed down the electrochemical gaps of the parent Sc3N@C80 isomers, making the complexes better electron donors but worse electron acceptors than the corresponding precursors.