Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße 34-36,14195, Berlin, Germany.

E-mail: b.sarkar@fu-berlin.de

The deprotonated forms of diamino- and teteraamino-benzenes (Figure 1) are typical examples of non-innocent ligands.¹ Traditionally metal complexes of these
ligands have either been studied because of their intriguing electronic structures,² or because of their proton-responsive nature.³ In this contribution, we will focus on recent contributions from our groups in which we have used these ligands to generate “masked” low-valent or high-valent compounds with intriguing organometallic
reactivity.⁴ Additionally, we will present modifications on the substitution pattern in these ligands that have led to air- and moisture-stable radical-bridged organometallic
compounds.⁵ Furthermore, we will discuss the relevance of such complexes, and in particular of the radical-bridged forms for generating state-of-the-art single-ion
magnets.⁶

Figure 1. The ligands 1,2-diaminobenzene (left) and 1,2,4,5-tetraaminobenzene (right).

1. W. Kaim, Inorg. Chem., 2011, 50, 9752–9765.
2. D. Herebian, E. Bothe, F. Neese, T. Weyhermüller, K. Wieghardt, J. Am. Chem. Soc., 2003, 125, 9116–9128.
3. O. Siri, P. Braunstein, M.-M. Rohmer, M. Bénard, R. Welter, J. Am. Chem. Soc. 2003, 125, 13793-13803.
4. a) M. van der Meer, Y. Rechkemmer, I. Peremykin, S. Hohloch, J. van Slageren, B. Sarkar, Chem. Commun. 2014, 50, 11104-11106; b) S. Suhr, R. Walter, J. Beerhues, U. Albold, B. Sarkar, Chem. Sci. 2022, 13, 10532-10545.
5. U. Albold, H. Bamberger, P. P. Hallmen, J. van Slageren, B. Sarkar, Angew. Chem. Int. Ed. 2019, 58, 9802-9806.
6. a) Y. Rechkemmer, F. D. Breitgoff, M. van der Meer, M. Atanasov, M. Hakl, M. Orlita, P. Neugebauer, F. Neese, B. Sarkar, J. van Slageren, Nature Commun., 2016, 7, 10467; b) D. Hunger, J. Netz, S. Suhr, et al, Nature Commun., 2025, 16, 2157