., a protonated amine), or preferably, a monoor polyvalent cation preferably having a valence of 1-5, of a metal selected from the group consisting of metals of Groups I to V and VIII, subgroups VIB and V IIB, and those of the lanthanide and actinide series of the Periodic Table, and n is an integer equal to the valence of M. Representative metal salts which can be used as latent catalysts to cure