Karl Kirchner

Highly reactive non-classical iron(II) polyhydride pincer complexes as catalysts hydrogenations and Hhydroborations

The synthesis, characterization, and reactivity of novel iron(II) polyhydride complexes that are supported by a pyridine-based PNP pincer ligand. These compounds are conveniently generated in situ from the corresponding hydrido alanate complexes by the addition of water. Along with the related hydrido borohydride complexes these compounds are catalysts for the regio- and stereoselective head-to-head dimerization of terminal alkynes giving enynes in high yields with up to 99% Z-selectivity. A comparison of the catalytic activity revealed a remarkable increase of the reaction rates in case of the novel polyhydrides. Moreover, these compounds are capable of catalyzing the hydroboration of terminal alkynes in the presence of pinacolborane. Also, this reaction exhibits a high degree of chemo-, regio- and stereoselectivity. These reactions involve bis- acetylide intermediate which are the key catalysts which are able to activate σ-bonds such as C-H and B-H bonds. In addition, some of these complexes are highly active for the hydrogenation of olefins and alkynes. Most recent results will be presented.

References
(1) Gorgas, N.; Alves, L. G.; Stöger, B.; Martins, A. M.; Veiros, L. F.; Kirchner, K. J. Am. Chem. Soc. 2017, 139, 8130-8133.
(2) Gorgas, N.; Stöger, B.; Veiros, L. F.; Kirchner, K. ACS Catal. 2018, 8, 7973-7983.