1-Thioacyl substituted oligonitriles 7,8,10 are prepared by nucleophilic ring opening reactions of 1-thia-3,5-diazinium salt 5. Alkylation of 8 with oxonium salts furnishes the corresponding azavinylogous iminium salts 11, which may be converted to 1,5-diamino-2,4-diazapentamethinium salts 12 by reaction with secondary amines. Alkylation of 10c and subsequent condensation with thiobenzamide lead to the new oligonitrile 13 with a 12 pi-system, the longest oligonitrile derivative known so far. (C) 1997 Elsevier Science Ltd.