[60]Fullerene displacement from fac-(dihapto-[60]fullerene)(dihapto-1,2-bis-(1,10-phenanthroline) tricarbonyl tungsten(0)

The Lewis bases triphenyl phosphine and tricyclohexyl phosphine (L) displace [60]fullerene (C60) from fac-(η2-C60)(η2-phen)W(CO)3 (phen=1,10-phenanthroline) to produce fac-(η2-phen)(η1-L)W(CO)3. Under flooding conditions, the reactions were first order with respect to fac-(η2-C60)(η2-phen)W(CO)3. The order with respect to C60 and L depends on the reaction conditions i.e., whether [C60]/[L] ≈ 0 or 0⩽It [C60]/[L] ≈ 1. Two limiting cases of an interchange displacement of [60]fullerene from fac-(η2-C60)(η2-phen)W(CO)3, whose relative contributions to the overall mechanism depend on the nature of the solvent, are proposed based on the rate law and on the activation parameters. The mechanism involves an initial [60]fullerene dissociation to produce (i) the electronically unsaturated intermediate (η2-phen)W(CO)3 for the dissociative displacement and (ii) the solvated intermediate fac-(solvent)(η2-phen)W(CO)3 for the solvent-assisted [60]fullerene dissociation. The W–C60 bond energy in fac-(η2-C60)(η2-phen)W(CO)3 was estimated to be in the vicinity of 105 kJ/mol based on the enthalpy of activation of the step where presumably [60]fullerene dissociates from fac-(η2-C60)(η2-phen)W(CO)3 to produce (η2-phen)W(CO)3.