  We report low-temperature transport measurements through molecules of Gd
metallofullerenes between superconducting suspended electrodes. The presence
and number of molecules in the 2 nm-wide gap between electrodes was determined
by high resolution transmission electron microscopy. We find that a junction
containing a single metallofullerene dimer between superconducting electrodes
displays signs of proximity-induced superconductivity. In contrast, no
proximity effects develops in junctions containing larger cluster of
metallofulerenes. These results can be understood by taking into account
multiple Andreev reflections, and the spin states of the Gd atoms.
