Strategies to stabilize exohedral #eta#~5- and #eta#~6- fullerene transition metal organometallic complexes: A molecular orbital treatment

摘要

Transition metal fragments are designed to overcome the unfavourable interaction arising from the splayed -out #pi#-orbitals of the five- and six-membered rings of C_(60) in complex formation. Semiemprical studies at the PM3(tm) level on a series of C_(60)MC_NH_N complexes suggest that, with the appropriate transition metal fragment, it is possible to stabilize #eta#~6- complexes of C_(60). Isodesmic equations of the type C_Mh_mMC_nH_n + C_(60) -> C_(60)MC_nH_n + C_Mh_m indicate that C_3H_3Co and C_3H_3Rh are ideal fragments in stabilizing #eta#~6-C_(60) complexes. In comparison, #eta#~5- complexes are less favourable; structural modifications such as those in the recently synthesized C_(60)Ph_5- should readily help #eta#~5-bonding.