Complexes of Gold(I), Silver(I), and Copper(I) with Pentaaryl[60]fullerides

Gold(I), silver(I), and copper(I) phosphine complexes of 6,9,12,15,18-pentaaryl[60]fullerides 1a and 1b, namely, [(4-MeC6H4)5C60]Au(PPh3) (2a), [(4-t-BuC6H4)5C60]Au(PPh3) (2b), [(4-MeC6H4)5C60]Ag(PCy3) (3a), [(4-t-BuC6H4)5C60]Ag(PPh3) (3b), [(4-t-BuC6H4)5C60]Ag(PCy3) (3c), [(4-MeC6H4)5C60]Cu(PPh3) (4a), and [(4-t-BuC6H4)5C60]Cu(PPh3) (4b), have been synthesized and characterized spectroscopically. All complexes except for 3c were also characterized by single-crystal X-ray diffraction. Several coordination modes between the cyclopentadienyl ring embedded in the fullerene and the metal centers are observed, ranging from η1 with a slight distortion toward η3 in the case of gold(I), to η2/η3 for silver(I), and η5 for copper(I). Silver complexes 3a and 3b are rare examples of crystallographically characterized Ag(I) cyclopentadienyls whose preparation was possible thanks to the steric shielding provided by fullerides 1a and 1b, which stabilizes these complexes. Silver complexes 3a and 3b both display unexpected coordination of the cyclopentadienyl portion of the fulleride anion with Ag(I). DFT calculations on the model systems (H5C60)M(PH3) and CpMPH3 (M = Au, Ag, or Cu) were carried out to probe the geometries and electronic structures of these metal complexes.