Geometric and Electronic Structures of Os3(CO)9(μ3-η2,η2,η2-C60), Os3(CO)8(P(CH3)3)(μ3-η2,η2,η2-C60), and Their Anions (Q = −1 to −4): Reduction-Induced Conversion of π to σ C60−Metal Complexes

The geometries and electronic structures of Os 3 (CO) 9 (μ 3 -η 2,η 2,η 2 -C 60 ) (OsF1), Os 3 (CO) 8 (P(CH 3 ) 3 )(μ 3 -η 2,η 2,η 2 -C 60 ) (OsF2), and their mono-, di-, tri-, and tetra-anions were calculated using a density functional method. Our calculations show that all three Os atoms are coordinated to C 60 in a π-type mode for the mono- and dianions, as well as in the neutral OsF1 and OsF2 complexes, but that third and fourth electron reductions form mixed σ−π-type coordinated compounds. A third electron reduction produces the Os 3 (CO) 9 (μ 3 -η 2,η 2,η 1 -C 60 ) 3 - and Os 3 (CO) 8 (P(CH 3 ) 3 )(μ 3 -η 2,η 2,η 1 -C 60 ) 3 - complexes, while a fourth electron reduction produces the Os 3 (CO) 9 (μ 3 -η 2,η 1,η 1 -C 60 ) 4 - and Os 3 (CO) 8 (P(CH 3 ) 3 )(μ 3 -η 2,η 2,η 1 -C 60 ) 4 - complexes. Our reduction potentials are calculated, in qualitatively good agreement with experimental data obtained using cyclic voltammetry.