Anionic Cyclopentadienyl C 60 Complexes of Molybdenum and Tungsten; The Strange Case of Iron

Thermal and photochemical reactions of the carbonylate salts A[(η 5 ‐C 5 H 5 )Fe(CO) 2 ], A[(η 5 ‐C 5 H 5 )Mo(CO) 3 ] and A[(η 5 ‐C 5 H 5 )W(CO) 3 ] (A = Na, PPN) in THF with C 60 result in all cases in electron transfer to give [C 60 ] − and the transient 17‐electron, metal‐centered radicals CpFe(CO) 2 , CpMo(CO) 3 and CpW(CO) 3 , respectively. Subsequent self‐coupling of the three metal‐centred radicals then results in the formation of the metal‐metal bonded dimers [CpFe(CO) 2 ] 2 , [CpMo(CO) 3 ] 2 and [CpW(CO) 3 ] 2 . In contrast, while the mixture of Na[C 60 ] and [CpFe(CO) 2 ] 2 does not react further under photochemical conditions, photolysis of mixtures of Na[C 60 ] and both [CpMo(CO) 3 ] 2 and [CpW(CO) 3 ] 2 ultimately results in complete homolysis of the dimers and regeneration of the corresponding metal‐centered radicals, which then combine with the [C 60 ] − remaining in solution to form the η 2 ‐C 60 complexes A[CpMo(CO) 2 (η 2 ‐C 60 ] and A[CpW(CO) 2 (η 2 ‐C 60 ]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)