Zwitterionic 1-Phosphonioalkyl Dithiophosphinates.-The title compounds such as (II) or the seleno analogues (III) and (IV) are obtained by the oxidation of an ylidylphosphine as well as from the addition of ylides (VI) to the perthiophosphonic anhydride (VII). These zwitterions can be deprotonated [(VIIIa) → (IX)] and alkylated [(VIIIb) → (XIV)] to give anions or cations. (IX) forms chelates with Ni 2+ , Pd 2+ and Pt 2+ . In addition, the reaction with (XI) makes it possible to prepare oxathiaphosphole sulfides. -(BREITSAMETER, F.; SCHROEDEL, H.-P.; SCHMIDPETER, A.; Heteroat. Chem. 9 (1998) 4, 433-437; Inst. Anorg. Chem.,