Synthesis, Characterization, and Electrochemical Properties of Mono-, Di-, and Trinuclear Transition Metal [60]Fullerene Complexes Containing Diphosphine Cis-Ph₂PCH=CHPPh₂ Ligand

New transition metal fullerene complexes containing cis-Ph₂PCH=CHPPh₂ (dppet) ligand have been investigated. The mononuclear complexes (η ²-C₆₀)M(cis-dppet) (1, 2; M = Pd, Pt) were prepared by reaction of C₆₀ with M(dba)₂ (dba = dibenzylideneacetone) followed by treatment with cis-dppet, while the in situ prepared 1 and 2 reacted with M¹(PPh₃)₄ to afford dinuclear complexes (η ² : η ²-C₆₀)M(cis-dppet)M¹(PPh₃)₂ (3–6; M, M¹ = Pd, Pt). Similarly, trinuclear complexes (η ² : η ²-C₆₀) M(cis-dppet)M¹(dppr) (7–10; M, M¹ = Pd, Pt; dppr = (eta; ⁵-Ph₂PC₅H₄)₂Ru) could be synthesized by reaction of the in situ prepared 3–6 with dppr. 1–10 were characterized by elemental analysis and spectroscopy. Cyclic voltammetric studies on 2 (M = Pt), 3 (M = Pd, M¹ = Pd) and 9 (M = Pt, M¹ = Pd) provided further evidence for the &eta ²-coordination of C₆₀ to one metal fragment or two metal fragments in these complexes.