Living Polymerization of α-Olefins:  Catalyst Precursor Deactivation via the Unexpected Cleavage of a B−C₆F₅ Bond

The titanium diamide complex [ArN(CH 2 ) 3 NAr]TiMe 2 ( 1a; Ar = 2,6- i Pr 2 C 6 H 3 ) reacts with B(C 6 F 5 ) 3 in pentane to give an insoluble yellow-orange solid ( 2a ). Complex 2a is a catalyst for the living polymerization of 1-hexene. Pentane suspensions of 2a slowly evolve methane over the course of several hours to give the new pentane-soluble derivative [ArN(CH 2 ) 3 NAr]Ti[CH 2 B(C 6 F 5 ) 2 ](C 6 F 5 ) ( 3a ), which was structurally characterized. Addition of a B−C 6 F 5 group across an intermediate Ti CH 2 unit is proposed. Compound 3a is inactive for the polymerization of α-olefins.