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 E_f 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.

Reaction of pyridine-2,4,6-tricarboxylic acid (ptcH₃) with Co(NO₃)2.6H₂O in presence of 4,4′-bipyridine (4,4′-bpy) in water at room temperature results in the formation of [Co₂(ptcH)₂(4,4′-bpy) (H₂O)4]·2H₂O, (1). The solid-state structure reveals that the compound is a dimeric Co(II) complex assembled to a 3D architecture via an intricate intra- and inter-molecular hydrogen-bonding interactions involving water molecules and carboxylate oxygens of the ligand ptcH^2-. Crystal data: monoclinic, spacegroup P2₁/c, a = 11·441(5) å,b = 20·212(2) å,c = 7·020(5) å, Β = 103·77(5)°,V= 1576-7(1) å³,Z = 2,R1 = 00363,wR2 = 0·0856,S = 1·000.