Coordination and Reactivity of a Structurally Responsive Phosphine-1-Azallyl Ligand
Abstract
The reactivity and coordination of a phosphine-1-azaallyl (P^AzA) ligand was explored using palladium (Pd) and ruthenium (Ru) complexes. Small molecules, H2, O2, and organic acids were added to a Pd(II) dimer to explore small molecule activation with a complex bearing a structurally responsive ligand. Notably, the 1-azaallyl moiety of a Pd(II) dimer was proton-responsive toward H2 and organic acids may be harnessed under catalytic conditions. The possible coordination modes of the P^AzA ligand were further explored by synthesising a Ru-P^AzA complex. The compound was proposed to exist in an equilibrium of three complexes that stabilise the Ru-center, suggesting a coordination site is easily accessible by a substrate. Preliminary experiments with pyridine or phenylacetylene and the Ru-P^AzA complex indicated a coordination site was accessible within seconds. Notably, reactivity studies suggested the Ru-P^AzA complex could be an active catalyst for alkyne cyclisation.