The syntheses of Co(AH2)2X2 (AH2 = 1-methyl-4, 4-dimercaptopiperidine, X = Cl Br, I, acetate, propanate, perchlorate, nitrate and sulphate), M(AH2) Cl2 (M = Cd, Zn) are described. According to IR and UV-visible data it seems most probable that the aminogem-dithiol (AH2) coordinates Co via both sulphur atoms, but Zn and Cd via one sulphur. A square pyramidal geometry about Co and a tetrahedral geometry about Zn and Cd are proposed. In no case has coordination via nitrogen been found. Strong X-H...N hydrogen bonds have been observed in most of these complexes. © 1983.