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.