Carbon-based aromatic compounds with the general formula C_nH_n are not only a universal substance class in organic chemistry but are also prominent ligands in organometallic chemistry. In contrast to free benzene, benzene ligands, coordinated to transition metal fragments show a reduced tendency to electrophilic aromatic substitutions, which is caused by the significantly reduced π-electron density.^[1] Compared to the organic benzene, the isolobal hexaphospha-benzene ligand shows similar structural features. However, very little is known about its reactivity and its tendency towards electrophilic or cationic functionalization.^[2] This contribution explores the reactivity of such a hexaphospha-benzene containing transition-metal complex as the inorganic analog of the ubiquitous benzene ligand towards oxidation as well as electrophilic functionalization with main group electrophiles and radical scavengers. While functionalization of smaller polyphosphorus complexes typically lead to mono-functionalized or ring-inserted products,^[3] ongoing research on the reactivity of this cyclo-P₆ moiety also reveals the possibility of multiple substitutions to take place. The selectivity of these reactions can be decisively modified by the choice of main group electrophile. Our approach enables the targeted and selective synthesis of novel cationic polyphosphorus complexes, which bridge the gap between the reactivity of organic and inorganic aromatic systems.

 

[1]  a) V. Graves, J. J. Lagowski, Inorg. Chem. 1976, 15, 577–586; b) H. P. Fritz, E. O. Fischer, Z. Naturforsch. B 1957, 12, 67–68.

[2]  A. Garbagnati, M. Seidl, G. Balazs, M. Scheer, Chem. Eur. J. 2022, e202200669.

[3]  a) C. Riesinger, G. Balázs, M. Seidl, M. Scheer, Chem. Sci. 2021, 12, 13037–13044; b) L. Zimmermann, C. Riesinger, G. Balazs, M. Scheer, Chem. Eur. J. 2023, e202301974; c) C. Riesinger, G. Balázs, M. Bodensteiner, M. Scheer, Angew. Chem. Int. Ed. 2020, 59, 23879–23884; d) C. Riesinger, L. Dütsch, G. Balázs, M. Bodensteiner, M. Scheer, Chem. Eur. J. 2020, 26, 17165–17170.