We have measured the far infrared transmittance of Sc-2@C-84 and Er-2@
C-82 at 1.5 K between 30 and 200 cm(-1). Both materials are observed t
o have a large primary absorption feature centered at 95 cm(-1) with a
width of approximately 50 cm(-1), as well as a number of secondary ab
sorption features which are different in the two materials, This is th
e first study of the far infrared properties of metallofullerenes and
may help in the determination of the structural and electronic propert
ies of these materials.