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

The tetrylenes Ge(Ar-Me6), and Sn(Ar-Me6)(2) (Ar-Me6 = C6H3-2,6-(C6H2-2,4,6-(CH3)(3))(2)) reacted with dimethylzinc to afford the insertion products (Ar-Me6)(2)Ge-(Me)ZnMe (1) and (Ar-Me6)(2)Sn(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 (Ar-Me6)(2)Ge(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(Ar-Me6)(2) with dimethylzinc yielded (ArZnMe)-Zn-Me6 with a linearly coordinated zinc atom via ligand exchange but no characterizable, new lead product was obtained. The reaction of Sn(Ar-Me6)(2) with dimethylzinc is reversible in hydrocarbon solution at room temperature and displayed a dissociation constant K-diss and a Delta G(diss) 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.