Methylisothiocyanate, MeN=C=S, in ethanol reacted with copper(I) giving a tetranuclear complex [Cu{mu(3)-SC(=NMe)(OEt)}](4) (1). Similar reaction of allylisothiocyanate, CH2=CHCH2N=C=S, and copper(I) in methanol gave a hexanuclear complex, [Cu{mu(3)-SC(=NC3H5)(OMe)}](6) (2). They show tetrahedral Cu-4 and octahedral Cu-6 cores, respectively. There are two structural similarities in both complexes : (i) a thiolato moiety [-N=C(S-)-] which bridges three copper atoms with a monodentate nitrogen atom and a bridging sulphur atom and (ii) a trigonal planar geometry for copper(I) coordinated by one nitrogen atom and two sulphur atoms. Each iminomethanethiolato ligand is formed in situ in solvent. H-1 NMR shows the reaction is initiated by a coordination of an isothiocyanate to copper(I).