Applications of PC(sp³)P Iridium Complexes in Transfer Dehydrogenation of Alkanes

Iridium ethylene complexes based on the PC­(sp³)P pincer-type triptycene ligand have been synthesized. Complexes bearing various substituents on the phosphines have been investigated as catalysts in transfer dehydrogenation of alkanes. The complex 8a, which bears isopropyl groups, has demonstrated high stability and activity when used as a catalyst in the disproportionation of 1-hexene at 180 °C and in the transfer dehydrogenation of linear and cyclic alkanes with tert-butyl­ethylene as a hydrogen acceptor at 200 °C. A similar complex bearing a CH₂NMe₂ group, 33, allowed support of the catalyst on γ-alumina for operation in a heterogeneous mode.