Preparation and study of some dithiolylium salts

The salts 3,5-diamino- or 3,5-di(methylamino)-1,2-dithiolylium perchlorate or bromide and 4-chloro-(or 4-bromo-)3,5-diamino- or 3.5-di(methylamino)-1,2-dithiolylium chloride or bromide have been prepared by oxyation of dithiomalonamide or NN′-dimethyldithiomalonamide. Conductivity, molecular-weight, 1H n.m.r., u.v.,i.r., and polarographic measurements are reported. The removal of a proton from the CH2 group of the dithiomalonamides gives a five-membered ring with pseudo-aromatic character. All the experimental data support considerable π bonding between the sulphur atoms. and this confers great stability on the disulphide group. The stability of the 3,5-diamino-or 3,5-di(methylamino)-1,2- dithiolylium salts is greater than that of the 4-chloro-3, 5-diamino- or 3,5-di(methylamino)-1,2-dithiolylium salts. The reduction of these salts occurs in one two-electron wave. Mono- and bis-dithiolylium salts of tetrachloro-ferrate(III), -cobaltate(II), -niccolate(II), and -cuprate(II) have also been prepared. Their magnetic moments and electronic and i.r. spectra suggest a tetrahedral configuration for the [FeCl4]- anions and a distorted tetrahedral configuration for the [MCl4]2–(M = Co, Ni, or Cu) anions, and absence of co-ordination of the dithiolylium ions which act as cations.