Sigma bond metathesis with pentamethylcyclopentadienyl ligands in sterically crowded (C_5Me_5)_3M complexes

摘要

To further explore the reactivity of the (C_5Me_5) ~- ligand in the sterically crowded (C_5Me_5) _3M complexes, reactions with PhEEPh (E = S, Se, Te) have been examined. With M = La, Pr, Nd, Sm, and Y, PhSSPh reacts to form the expected reduction products, [(C_5Me_5)_2M(SPh)] _2, but the major organic byproduct is not the sterically induced reduction product, (C_5Me_5)_2. Instead, the sigma bond metathesis product, C_5Me_5SPh, is the major byproduct. In contrast, reactions with (C_5Me_5) _3Ce and (C_5Me_5)_3U gave a mixture of C_5Me_5SPh and (C_5Me_5)_2 as byproducts. PhSSPh reactions with the lanthanide nitrile adducts, (C _5Me_5)_3Ln(NCCMe_3)_2 (Ln = La, Ce) and (C_5Me_5)_3Nd(NCCMe_3), formed [(C_5Me_5)_2Ln(SPh)(NCCMe _3)]_2 and only C_5Me_5SPh as the byproduct. PhSeSePh reactions paralleled the PhSSPh results, but reactions of PhTeTePh with (C_5Me_5)_3La, (C_5Me _5)_3Sm, and (C_5Me_5) _3La(NCCMe_3)_2 gave only (C_5Me _5)_2 as a byproduct.