Teaming up main group metals with metallic iron to boost hydrogenation catalysis
Christian Färber, Philipp Stegner, Ulrich Zenneck, Christian Knüpfer, Georg Bendt, Stephan Schulz, Sjoerd Harder
Abstract
Abstract Hydrogenation of unsaturated bonds is a key step in both the fine and petrochemical industries. Homogeneous and heterogeneous catalysts are historically based on noble group 9 and 10 metals. Increasing awareness of sustainability drives the replacement of costly, and often harmful, precious metals by abundant 3 d -metals or even main group metals. Although not as efficient as noble transition metals, metallic barium was recently found to be a versatile hydrogenation catalyst. Here we show that addition of finely divided Fe 0 , which itself is a poor hydrogenation catalyst, boosts activities of Ba 0 by several orders of magnitude, enabling rapid hydrogenation of alkynes, imines, challenging multi-substituted alkenes and non-activated arenes. Metallic Fe 0 also boosts the activity of soluble early main group metal hydride catalysts, or precursors thereto. This synergy originates from cooperativity between a homogeneous, highly reactive, polar main group metal hydride complex and a heterogeneous Fe 0 surface that is responsible for substrate activation.