This application is concerned with tetrathiapentalene and tetraselenapentalene compounds. Specifically, it is concerned with 1, 3, 4, 6-tetrathia-2, 5-dihetero-pentalene and 1, 3, 4, 6-tetraselena-2,5-dihetero-pentalene compounds having the formula ##STR1## wherein X is S or Se; each of Y.sup.1 and Y.sup.2 is O, S, or Se; each of Z.sup.1 and Z.sup.2 is --SR, SeR or ##STR2## wherein R and R.sup.I are H, alkyl, aryl, or together form a ring of carbon atoms; and An is the anion of a strong acid. These compounds are key synthetic intermediates for the preparation of tetrathiafulvalene and tetraselenafulvalene materials.