The reaction of [(Me3Si)(2)N](2)S With an equimolar amount of SeCl4 in dioxane at 50 degreesC affords [(Se2SN2)Cl](2) (1) in excellent yield. Crystals of 1 are orthorhombic, space group Pbca, with a = 8.5721(7) Angstrom, b = 7.8336(6) Angstrom, c = 15.228(1) Angstrom, and Z = 8. The crystal structure contains two planar Se2SN2.+ rings which are linked by intermolecular Se...Se interactions [d(Se-Se) = 3.0690(7) Angstrom]. The EI mass spectrum shows Se2SN2.+ as the fragment of highest mass. Both the N-14 and Se-77 NMR spectra show a single resonance (-52 and 1394 ppm, respectively). The solid [(Se2SN2)Cl](2) gives a strong ESR signal indicating the presence of a Se2SN2.+ radical. The Raman spectrum was assigned through normal coordinate treatment involving a general valence force field. The vibrational analysis yielded a good agreement between the observed and calculated wavenumbers.