A new copper(I) thiocyanato thiocyanogen complex

The reaction between Cu²⁺ and SCN^?, in glacial acetic acid at a Cu/SCN ratio, of 1:4, gave a dark red solution that exhibited an absorption band at 496 nm. The colour of the freshly prepared solution was bleached by water with concomitant production of SO₄^2? ion. On standing, the stability of the colour towards water is increased and the position of the absorption band shifts to a higher wavelength. It is inferred that the thiocyanogen produced on oxidation of SCN^? by Cu²⁺ is stable in the non-aqueous medium and is coordinated together with SCN^? in a Cu(I) complex. The bleaching action of water is attributed to the hydrolysis of thiocyanogen, mainly to SO₄^2?. The presence of thiocyanogen enhanced polymerization and subsequent deposition of an orange-brown solid complex. On the basis of chemical, spectral, and thermal analyses the formula K[Cu(SCN)₂(NCS—SCN)], is assigned to the new compound.