Tetrasulphur tetranitride reacts with excess of VCI4 in CH2Clz to form a mixture of VCI2(S2N3) (2) and S2N2-VCI4 (3), whereas with excess of TiCI4 only S4N4*TiCI4 (1) is formed. Crystals of (2) are triclinic, space group PT, with a = 571.3(2), b = 695.7(3), c = 772.9(3) pm, a = 95.38(3), p = 99.62(3), y = 97.58(3)", and Z = 2. The structure was refined to R = 0.053 for 1 601 unique observed diffractometer data. It consists of chlorine-bridged dimers, linked by additional weak V-N interactions to form polymeric chains. The six-membered VNSNSN ring is effectively planar.The complexes S4N4*TiC14, S4N4*VCI4, S4N4.2SnCl4, and S4N4*2TiC14 were described by Goehring and co-workers,' but it was not until 1969 that the i.r. spectra of S4N4*TiCI4, S4N4*2TiC14, and S4N4*VC14 were reported.2 These i.r. spectra differ appreciably from those of other known adducts of S4N4,3 which prompted us to reinvestigate the reactions of S4N4 with VC14 and TiC14 under similar experimental conditions to those previously employed. Further details of the reactions of S4N4 with Lewis acids may be found in the review by Heal!