CYCLIC 1,8-NAPTHTHALENEDIYL COMPOUNDS CONTAINING GROUP-14 HETERO-ATOMS

Reaction of 1,8-naphthalenediylmagnesium with dimethylgermanium dichlo ride gave only dimethyl(1,8-naphthalenediyl) germanium (7), whereas us e of 1,8-dilithionaphthalene gave a mixture of products, consisting ma inly of 7 and its ''dimer'' 7,7,14,14-tetramethyldinaphtho[1,8-bc:1', 8'-fg][1,5] digermocin (8). The silicon analogue (12) of 8 was prepare d in a two-step procedure, starting from 1,8-dilithionaphthalene and 1 ,1,2,2-tetrachloro-1,2-dimethyl-disilane. The molecular structures of 8 and 12 were determined by single crystal X-ray diffraction studies. Both structures are centrosymmetric. The central eight-membered rings containing the (CH3)(2)E moieties (E = Si, Ge) have a chair-like confo rmation. The naphthalene rings are quasi-coplanar and show strong out- of-plane distortions which are larger for 12 than for 8.