[Hg4 Te8 (Te2 )4 ]8- : A Heavy Metal Porphyrinoid Embedded in a Lamellar Structure.

The use of ionic liquids (Cn C1 Im)[BF4 ] with long alkyl chains (n=10, 12) in the ionothermal treatment of Na2 [HgTe2 ] led to lamellar crystal structures with molecular macrocyclic anions [Hg8 Te16 ]8- (1), the heaviest known topological relative of porphyrin. [Hg8 Te16 ]8- differs from porphyrin by the absence of an electronic π-system, which prevents a "global" aromaticity. Quantum chemical studies reveal instead small ring currents in the pyrrole-type five-membered rings that indicate weak local (σ) aromaticity. As a result of their lamellar nature, the compounds are promising candidates for the formation of sheets containing chalcogenidometalate anions.