Treatment of dithiirane 1-oxides 9 with (Ph 3 P) 2 Pt(η 2 -CH 2 = CH 2 ) (3) yielded the corresponding four-membered (sulfenato−thiolato)Pt II complexes 7 in high yields. The structures of 7 were determined by 31 P NMR spectroscopy and, for 7e, X-ray crystallography. Treatment of dithiirane 8 with