Kinetic and Mechanistic Investigation of Metallacycle Ring Opening in an Ortho-Metalated Lutetium Aryl Complex

Abstract

Reactivity involving metallacycle ring opening of ortho-metalated bis(phosphinimine)carbazolide complexes (LPh-κ3N,κ2CP-Ph)Lu(THF) (1a) and (LPipp-κ3N,κ2CP-Ph)Lu(THF) (1b); L = [1,8-(Ph2P═NAr)2dmc]; Ar = Ph (LPh), p-isopropylphenyl (LPipp); dmc = 3,6-dimethylcarbazolide) is described. Reaction of 1a,b with bulky anilines (2,4,6-trimethylaniline, MesNH2; 2,4,6-triisopropylaniline, TripNH2) promoted metallacycle ring opening of two ortho-metalated P-phenyl groups to liberate the bis(anilide) products (LPh-κ3N)Lu(NHMes)2 (2) and (LPipp-κ3N)Lu(NHTrip)2 (3). Regardless of the quantity of TripNH2 or MesNH2 utilized, double ring opening always prevailed to afford the bis(anilide) product, rather than the mono(anilide). In contrast, reaction of complex 1b with the bulkier reagent 2,4,6-tri-tert-butylaniline (Mes*NH2) only caused metallacycle ring opening of one ortho-metalated P-phenyl group, affording the mono(anilide) complex (LPipp-κ3N,κCP-Ph)Lu(NHMes*) (4) exclusively. Complex 4 rapidly undergoes an intramole...