ISSN 1017-2548(Print)
ISSN 2234-8530(Online)
Volume 26, Number 3
JKCSEZ 26(3)
June 20, 1982 

The thioxanthylium ion ard anthracenium ion have coplanar geometries. The empty pz-orbitals of the positive centers in the cations, therefore, overlap with the π-orbitals of the fused benzen rings. These cations have aromatic characters, obeying Huckel's (4n + 2)π rule. The contribution of the sulfur atom to aromatic stabilization was estimated by comparing the 19F-nmr chemical shifts of the thioxanthylium ions and anthracenium ions.