Reaction of Me2PCH2CH2PMe2 or o-C6H4(PMe2)(2) (LL) with a suspension of ScI3 or YI3 in MeCN solution under rigorously anhydrous and oxygen-free conditions produced the highly unusual complexes [ScI3(LL)(2)], [YI3(Me2PCH2CH2PMe2)(2)], and [YI3{o-C6H4(PMe2)(2)}2MeCN]. X-ray crystal structures reveal that the scandium complexes adopt seven-coordinate, pentagonal-bipyramidal geometries with chelating diphosphines, while the eight-coordinate [YI3{o-C6H4(PMe2)(2)}(2)MeCN] is dodecahedral. The complexes were characterized by microanalysis and IR and multinuclear NMR spectroscopy. Solid-state NMR data (Sc-45, Y-89, P-31) and variable-temperature solution NMR data (H-1, P-31{H-1}, Sc-45) are presented and compared, leading to the conclusion that the same species are present in both the solid state and CH2Cl2 solution. Attempts to prepare complexes with other scandium halides and with aryl diphosphines and o-C6H4(AsMe2)(2) are briefly described.