The novel latent epoxy curing agent and commercial epoxy system designated MY750/Cu(PGE-EMI)4Cl2 shows remarkable properties under both extended storage and cure conditions. For example, after a period of 2600 hours at ambient temperature the viscosity of an MY750/Cu(PGE-EMI)4Cl2 mixture is still low enough (ca. 3 x 10(6) cps) to be measured at ambient temperature, while the corresponding MY750/(PGE-EMI) adduct mixture is too viscous to be measured (ca. 8 x 10(6) cps) after only 430 hours. The slower increase in viscosity of the complex mixture indicates that it is much more stable than its parent imidazole when dispersed in an epoxy prepolymer over an extended period of time. FTIR and H-1 n.m.r. data suggest that after heating an MY750/Cu(PGE-EMI)4Cl2 mixture for 5 minutes at high temperatures (120-140-degrees-C) and a room temperature quench, almost no further cure occurs thereafter.