NON‐Ligated N‐Heterocyclic Tetrylenes

We report on the synthesis of N‐heterocyclic tetrylenes ligated by the NON‐donor framework 4,5‐bis(2,6‐diisopropylphenyl‐amino)‐2,7‐di‐tert‐butyl‐9,9‐dimethylxanthene. The molecular structures of the germylene (3), stannylene (4) and plumbylene (5) where determined by X‐ray diffraction studies. Furthermore, we present quantum chemical studies on the σ‐donor and π‐acceptor properties of 3–5. Additionally, we report on the reactivity of the tetrylenes towards the transition metal carbonyls [Rh(CO)2Cl]2, [W(CO)6] and [Ni(CO)4]. The isolated complexes (6 and 7) show the differing reactivity of NHTs compared to NHCs. Instead of just forming the anticipated complex [(NON)Sn−Rh(CO)2Cl], 4 inserts into the Rh−Cl bond to afford [(NON)Sn(Cl)Rh(CO)(C6H6)] (6, additional CO/C6H6 exchange) and [(NON)Sn(Cl)Rh2(CO)4Cl] (7). By avoiding halogenated transition metal precursors in order to prevent insertion reactions, germylene 3 shows “classical” coordination chemistry towards {Ni(CO)3} forming the complex [(NON)Ge−Ni(CO)3] (8). High NON! Different ways for the synthesis of NON‐ligated N‐heterocyclic germylene (3), stannylene (4) and plumbylene (5) were carried out. The title compounds were characterized using standard methods including X‐ray diffraction. Initial investigations on the coordination behavior of 3–5 towards [Rh(CO)2Cl]2, [W(CO)6] and [Ni(CO)4] were performed. The σ‐donor and π‐acceptor properties were evaluated using density functional theory.