Synthesis and Reactivity of Oxorhenium(V) Complexes Incorporating 2,6-Bis[(diphenyl)methyl]diamidopyridine (DPMDAP) Pincer Ligands as the Basic Component of Transition Metal Frustrated Lewis-Pair Catalysts

Oxorhenium(V) complexes incorporating a N,N '-(pyridine-2,6-diylbis(methylene))bis(2,6-dibenzhydryl-4-methylaniline), DPMDAP, pincer ligand are outlined. These complexes, with tris(pentafluorophenyl)borane (B(C6F5)3), are frustrated Lewis-pair (FLP) catalysts, and their reactivity for the hydrogenation of unactivated olefins is described. The influence of the sterics of the DPMDAP pincer ligand was probed with steric maps and percent buried volume (%V b) calculations. These data suggest that the DPMDAP ligand exerts the greatest steric influence on the oxo ligand. However, a comparison of the catalytic activity among the various catalysts suggests that the steric and electronic properties of the ligand at the basal position in these square pyramidal complexes may be just as important.