New compounds with Ge/Ge and Ge/C multiple bonds

Treatment of GeCl2 · dioxane with the Grignard reagent RMgBr (R = 2,5-tBu2C6H3) furnishes the tetraaryldigermene R2Gedouble bond; length as m-dashGeR2 (4). The X-ray structure analysis of 4 reveals a long Gedouble bond; length as m-dashGe double bond of 236.4 pm and the largest trans-bending angles of the substituents (42.6° and 37.2°) observed so far. The reaction of hexa-2,4-diyne with the germylene R2Ge: (R = 2-tBu-4,5,6-Me3C6H) yields red crystals of the acetylene-bridged bis(germaethene) (Me)R2Gedouble bond; length as m-dashC–Ctriple bond; length of mdashC–Cdouble bond; length as m-dashGeR2(Me) 7, the red colour of which indicates conjugation between the two double bonds.