Magnetic response of dithiin molecules: is there anti-aromaticity in nature?

Ab initio current density formalism is used to investigate the response to external magnetic fields of the only known naturally occurring moieties which are formally anti-aromatic, i.e., dithiines. Magnetic susceptibility, nuclear shielding constants, and the topology of induced current densities indicate that although these molecules satisfy Hückel’s rule for being anti-aromatic, they are not. In chiral dithiines, the multipolar expansion of the response contains non-vanishing anapole terms associated with ‘spinning cuff’ current lines.