Silver perchlorate induced rearrangement of a tetraarylethene involving an apparent oxygen migration

An H-shaped tetraarylethene ligand was prepared and shown to react with silver perchlorate to produce a crystalline silver complex of a rearranged ligand. X-ray crystallography revealed that this involved the formation of a phenanthrene ring system with the apparent migration of an oxygen atom. We believe that this rearrangement proceeds via the intermediacy of a spirodienone.