Ethylenedioxy- and ethylenedithiodithiadiselenafulvalenedithiolates are subjected to sulfur-selenium exchange, in which one selenium atom in the molecular skeleton is replaced by an outside sulfur atom. The reaction of the exchanged dithiolates with 2-methylthio-1,3-dithiolylium ion gives the corresponding thioquinone-1,3-dithiolemethides as new donor molecules.