Reactivity of some cuprous salts towards tenmembered macrocyclic disulphides: a new route to the synthesis of Cu(II)-thiolates

Cuprous ion is found to be quite reactive towards disulphide present in a macrocycle. Thus, when [Cu(MeCN)4] BF4 or [Cu(MeCN)4]ClO4 is allowed to reflux in acetonitrile with a ten-membered macrocycle containing two amino nitrogens and one disulphide donor in an atmosphere of nitrogen, electron transfer takes place from the metal centre to the disulphide group. As a result, copper is oxidised to the +2 state and the disulphide reduced to thiolates. The thiolates then bind the Cu(II) and form discrete and neutral CuN2S2 complexes. Syntheses of two new CuN2 S2 complexes have been achieved following this route. The reactions take place smoothly and give the desired product in excess of 25% yield with respect to the macrocycle. Electronic absorption spectral results are consistent with a nearly square planar geometry. Each of the two complexes isolated exhibits quasireversible Cu(II)/Cu(I) couple with Ef near - 0.3 V vs SCE. Both the complexes are further characterised by room temperature magnetic susceptibility, EPR spectroscopy at 298 and 77 K and elemental analyses