Applications of PC(sp(3))P Iridium Complexes in Transfer Dehydrogenation of Alkanes

Iridium ethylene complexes based on the PC(sp(3))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 degrees C and in the transfer dehydrogenation of linear and cyclic alkalies with tert-butylethylene as a hydrogen acceptor at 200 degrees C. A similar complex bearing a CH2NMe2 group, 33, allowed support of the catalyst on gamma-alumina for operation in a heterogeneous mode.