In the first neutral bis-fullerene complexes with tungsten(0) and molybdenum(0) [M(η2-C60)2(CO)2(dbcbipy)] [M = W and Mo, dbcbipy = 4,4′-di(butyl carboxyl)-2,2′-bipyridine] synthesized in solution, the metal atom coordination is distorted octahedral with two CO groups and the bipy group of dbcbipy in the equatorial plane and the metal atom binding in an η2-fashion to C–C bonds of two C60 at axial orientation to give a dumbbell shaped molecule.
