A full geometry optimization at the HF level has been carried out for the fullerene platinum complexes [Pt(PH3)(2)]C-n(60), n = 1, 2, and 6, and for the hexasubstituted palladium derivative [Pd(PH3)(2)]C-6(60). The computed geometries are in good agreement with those determined by X-ray diffraction. When there is just one platinum bound to C-60, the binding energy is found to be 11.7 kcal/mol higher than the calculated Pt-ethylene binding energy. The interaction between the metal and C-60 is basically local. As a matter of fact, the dissociation energy of the first metal group in [Pt(PH3)(2)]C-2(60) is just 2.7 kcal/mol lower than the dissociation energy of the Pt(PH3)(2) fragment in the monosubstituted derivative. The total binding energy of the six platinum groups in [Pt(PH3)(2)]C-6(60) has been computed to be 30.4 kcal/mol (5.1 kcal/mol per group). An important charge transfer from the metal group to the C-60 core has been detected, about 0.5e for the monosubstituted derivative and 2.2e for the hexasubstituted platinum complex. The Pd(PH3)(2) group has been determined to be more labile than the corresponding platinum group. The M-C-60 bond strength is noticeably weakened if the complex is reduced. Hence, the loss of C-60(-) from [Pt(PH3)(2)](2)(C-60)(-) is 12.5 kcal/mol more favorable than the loss of C-60 from its neutral partner.