Molecular Zinc Species with Ge–Zn and Sn–Zn Bonds: A Reversible Insertion of a Stannylene into a Zinc–Carbon Bond

The tetrylenes Ge­(ArMe6)2 and Sn­(ArMe6)2 (ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2) reacted with dimethylzinc to afford the insertion products (ArMe6)2Ge­(Me)­ZnMe (1) and (ArMe6)2Sn­(Me)­ZnMe (3), which feature Ge–Zn and Sn–Zn bonds as well as two-coordinate zinc atoms. Crystals of 1 were found to be unsuitable for X-ray crystallography, so the ethyl-substituted (ArMe6)2Ge­(Et)­ZnEt (2) was synthesized in a parallel way to provide crystals suitable for X-ray studies. These showed the structure to be similar to that of 3. The reaction of Pb­(ArMe6)2 with dimethylzinc yielded ArMe6ZnMe with a linearly coordinated zinc atom via ligand exchange but no characterizable, new lead product was obtained. The reaction of Sn­(ArMe6)2 with dimethylzinc is reversible in hydrocarbon solution at room temperature and displayed a dissociation constant Kdiss and a ΔGdiss of 0.0028(5) and 14(4) kJ mol–1 at 298 K, respectively. Compounds 1–4 were characterized by NMR and IR spectroscopy as well as by X-ray crystallography for 1, 3, and 4.