1,3-Dithia-2-stannacyclopentenes of types [graphic omitted] and [graphic omitted] have been prepared. These ring systems formed adducts with pyridine and ortho-phenanthroline. Transition-metal halides caused fission of the tin–sulphur bonds in the dithia-2-stannacyclopentenes to produce the dithiolato-derivatives of the transition metals.