Why are (NN2)Ni pincer complexes active for alkyl-alkyl coupling: ß-H elimination is kinetically accessible but thermodynamically uphill

Isomerization and olefin exchange experiments show that β-H elimination is kinetically viable but thermodynamically unfavorable in [(MeNN2)Ni-alkyl] complexes. The intermediacy of Ni-hydride species was corroborated by a trapping experiment. The alkyl complex [(MeNN2)Ni-propyl] catalyzes olefin isomerization