Synthesis, Characterization, and Hydrogenation Activity of Group 10 Metal Complexes Featuring Bulky Phosphine Ligands

Bulky, electron-rich phosphine ligands facilitate unique reactivity in various chemical systems and can stabilize metal species in unusual oxidation states or environments. Routes to bulky bis(phosphine) chelating ligands that mimic the sterics of the exceptionally bulky tri-tert-buylphosphine are explored with the ultimate goal of preparing novel catalyst systems of group 10 metals capable of hydrogenation. Attempts to target bulky phosphines from phosphinimine precursors highlight some interesting phosphinimine reactivity, however attempts to reduce the phosphinimine bond revealed limitations. Bis(aminophosphine) ligands present an alternate route to bulky bis(phosphines) and allow for tunability of the environment around phosphorus. The coordination of these ligands with palladium and nickel exhibit a novel bonding mode in which C-H or N-H activation of the ligand occurs to form strained metallacycles. Prepared compounds showed some activity as catalysts under hydrogen and isomerized 1-hexene to 2-hexene, offering support for their potential use as hydrogenation catalysts.MAS