Synthesis and characterization of the first transition-metal fullerene complexes containing bis(η6-benzene)chromium moieties

While photochemical reaction of C60 with an equimolar amount of Mo(CO)4(η6-Ph2PC6H5)2Cr (1) in toluene at room temperature produced bimetallic Mo/Cr fullerene complex fac/mer-(η2-C60)Mo(CO)3[(η6-Ph2PC6H5)2Cr] (2) in 87% yield, the thermal reaction of an equimolar mixture of C60, M(dba)2 (M = Pd, Pt; dba = dibenzylideneacetone) and (η6-Ph2PC6H5)2Cr (3) in toluene at room temperature afforded bimetallic M/Cr fullerene complexes (η2-C60)M[(η6-Ph2PC6H5)2Cr] (4, M = Pd; 5, M = Pt) in 88% and 92% yields, respectively. Products 2, 4 and 5 are the first transition-metal fullerene complexes containing bis(η6-benzene)chromium moieties. While 2, 4 and 5 were characterized by elemental analysis and spectroscopy, the crystal molecular structures of 4 along with the starting materials 1 and 3 have been determined by X-ray diffraction techniques.