C-H Bond Activation and Cracking of Cyclohexane Using Mass Spectrometry

Abstract

Gas-phase mass spectrometry is used to study the C-H activation of cyclohexane by [(phen)M(X)]+ (where phen = 1,10-phenanthroline; M = Ni, Pd, or Pt; X = H or CH3), forming the cyclohexyl species [(phen)M(c-C6H11)]+. Collision-induced dissociation of this species and cyclohexane-induced ion molecule reactions result in ring opening followed by “cracking” of the hydrocarbon chain and dehydrogenation of the cyclohexyl ring. The catalytic nature of these processes enables the continual production of smaller hydrocarbons, such as ethylene and propylene, from ring opening/cracking as well as benzene, cyclohexene, and one, two, or three hydrogen molecules from dehydrogenation. The metal used largely determines which pathway is favored by a species, with Pt species preferring the dehydrogenation pathway over the ring opening/cracking pathway.