Planar Silicon and Germanium Heterocyclotriynes and Their Isomorphous Nickel(0) Complexes

The syntheses of three strained silicon or germanium heterocyclotriynes, from the dilithium dianion of 2,2‘-diethynyltolane (Li 2 (OBET)) and the dialkyldichlorosilanes or dialkyldichlorogermane, are described. Reactions of the heterocyclynes with Ni(COD) 2 give the nickel(0) complexes in very high yield. The heterocyclynes and their nickel complexes have been characterized by a variety of spectral techniques, and the X-ray crystal structures of compounds Si( i -Pr) 2 (OBET), Ni[Si( i -Pr) 2 (OBET)], SiPh 2 (OBET), Ni[SiPh 2 (OBET)], GePh 2 (OBET), and Ni[GePh 2 (OBET)] are reported. The heterocyclynes and their nickel complexes possess isomorphous structures.