The title compound (C6H12N)Ph2P=N-S 3N3·C7H8 crystallizes in the monoclinic space group P21/n with unit cell dimensions: a = 9.9200(5), b = 16.3316(11), c = 15.7009(17) Å, β= 91.99(1)°, and Z = 4. The cyclotrithiazene ring adopts a chair conformation with equal bond distances and the norbornadiene is fused in an exo, exo fashion to the heterocycle. Norbornadiene addition to the cyclotrithiazene influences the bonding pattern in the ring as well as the P-N-S moiety.