Crystal structure of 2,2,3,3-tetra-methyl-1,1,1,4,4,4-hexa-phenyl-tetra-germane.

The mol-ecule of the title compound, C40H42Ge4, lies with its central Ge-Ge bond on an inversion centre giving rise to a zigzag backbone of four tetra-hedrally coordinated Ge atoms. The symmetrically independent Ge-Ge bonds are slightly shorter than in other organo-tetra-germanes whereas the Ge-CPh (Ph = phen-yl) and Ge-CMe (Me = meth-yl) distances have their usual values. In the crystal, (010) layers of Ph6Me4Ge4 mol-ecules with a parallel orientation of the Ge4 backbone exist, held together by van der Waals forces only. Main bond lengths in organo-substituted oligogermanes are compared.