Synthesis and structure of 9,10-bis(2,4,6-triisopropylphenyl)-9,10-dihydro-9,10-disilaanthracene

We prepared a 9,10-dihydro-9,10-disilaanthracene (DSA) derivative 4 bearing a bulky aryl substituent, a 2,4,6-triisopropylphenyl (Tip) group, on the silicon atoms via a Wurtz-type coupling reaction between two molecules of (2-chlorophenyl)(2,4,6-triisopropylphenyl)silane (3) in a head-to-tail fashion. The structural determination of cis-4 and trans-4 was examined using 1H NMR spectroscopy and theoretical calculations. In addition, the molecular structure of cis-4 was unambiguously determined by X-ray crystallography. The tricyclic DSA skeleton of cis-4 adopts a folded structure with a boat-like central ring in which the rotation about the Si–Tip bond is restricted. In contrast, theoretical calculations suggest that the tricyclic DSA skeleton of trans-4 has an almost planar structure.