Abstract

Abstract: Low-valent, low coordinate transition metal complexes represent a class of extraordinarily reactive compounds that can act as reagents and catalysts for challenging bond-activation reactions. The pursuit of these electron-deficient metal complexes in low oxidation states demands ancillary ligands capable of providing not only energetic stabilization but also sufficiently high steric bulk at the metal center. In a T-shaped geometry, the transition metal complexes possess a precisely defined vacant coordination site which, combined with the often observed high-spin electron configuration, exhibits unusually high selectivity of these compounds with respect to one-electron redox chemistry. In light of the intractable reaction pathways typically observed with related electronically unsaturated 3d transition metal complexes, the pincer coordination mode enables the isolation of low-valent compounds with more controlled and unique reactivity. We have investigated a series of T-shaped metal(I) complexes which may be regarded as ‘metalloradicals’ due to their selectively exposed unpaired electrons.1 The focus of the lecture will be the elucidation of structures and reactive patterns observed for such highly unsaturated complexes as well as catalytic reaction mechanisms. The identification and characterization of the paramagnetic species involved by NMR spectroscopy will be discussed.2 References 1. J. C. Ott, D. Bürgy, H. Guan, L. H. Gade, Acc. Chem. Res. 2022, 55, 857. 2. J. C. Ott, H. Wadepohl, M. Enders, L. H. Gade, J. Am. Chem. Soc. 2018, 140, 17413; L. S. Merz, C. K. Blasius, H. Wadepohl, L. H. Gade, Inorg. Chem. 2019, 58, 6102; J. C. Ott, H. Wadepohl, L.H. Gade, Angew. Chem. Int. Ed. 2020, 59, 9448. J. C. Ott, E. A. Suturina, I. Kuprov, J. Nehrkorn, A. Schnegg, M. Enders, L. H. Gade, Angew. Chem. Int. Ed. 2021, 60, 22856.