Coordination chemistry of anticrowns: Synthesis and X-ray crystal structure determination of the polydecker sandwich complexes of cyclic trimeric perfluoro-o-phenylenemercury with azulene and 6-(N,N-dimethylamino)pentafulvene

The interaction of cyclic trimeric perfluoro-o-phenylenemercury (o-C6F4Hg)3 (1) with azulene results in the formation of a complex, {[(o-C6F4Hg)3](azulene)} (2), containing one molecule of azulene per one macrocycle molecule. The complex represents a polydecker sandwich wherein the azulene units alternate with the molecules of the mercury anticrown. The reaction of 1 with 6-(N,N-dimethylamino)pentafulvene (DMAPF) also gives a 1:1 complex, {[(o-C6F4Hg)3](DMAPF)} (3), having a polydecker sandwich structure in the crystal. In complex 2, both the C5 and C7 rings of the azulene ligand are involved in the bonding to the Hg sites of 1. In complex 3, the C5 ring of the fulvene ligand together with its exocyclic carbon atom take part in the coordination to the mercury centres. In both adducts, the negatively charged five-membered ring of the azulene and, correspondingly, the fulvene moieties is arranged in the space between the central Hg3C6 rings of the adjacent macrocycles while the remaining portion of these moieties is disposed outside this space. The molecules of azulene and DMAPF in 2 and 3 are bonded to 1 through donation of their π-electrons on vacant orbitals of the Hg atoms. The synthesized 2 and 3 are the first examples of structurally characterized complexes of azulene and DMAPF with a non-transition metal compound.