Pyridine-2-azo-p-phenyltetramethylguanidine (PAPT) was synthesized and the properties of this compound examined. The dissociation constants of the conjugate acids in H2O are and at 25° C at I= 0.1, and in acetonitrile are and. The properties of metal-ligand chelates in acetonitrile have been examined and the stability constants for Ni2+, Co2+, and Zn2+ complexes measured. The rates of reaction of PAPT with Ni2+, Co2+, and Zn2+ in ...