Synthesis and characterisation of two examples of unsymmetrically disubstituted cyclotetra-thiazenes, 1,5-(x)(y)s<inf>4</inf>n<inf>4</inf>[x = ph<inf>3</inf>pn-and y = i) (p-ch<inf>3</inf>c<inf>6</inf>h<inf>4</inf>) ph<inf>2</inf>pn-and ii) (p-ch<inf>3</inf>c<inf>6</inf>h<inf>4</inf>)<inf>2</inf>phpn-]

1,5-[(p-tolyl)diphenylphosphinimino] (triphenyl-phosphinimino)tetrasulphurtetranitride, (I) and 1,5-[di(p-tolyl)phenyl-phosphinimino] (triphenylphosphinimino)tetrasulphurtetranitride, (II) are the first examples of heterodisubstituted tetrasulphur-tetranitride derivatives to be made. Their synthesis and structural characterization are described. © 1989, Taylor & Francis Group, LLC. All rights reserved.