Ligands containing linked 1, 4, 7-triazacyclononanes form dinuclear Zn (II) complexes at near neutral pH. Comparison of second-order rate constants for cleavage of HPNP (2- hydroxypropyl-4-nitrophenyl phosphate) at pH 7.6, 25° C and extent of cleavage of an oligoribonucleotide suggests that only one dinuclear complex has cooperative catalysis between the Zn (II) centers. This complex has a bridging alkoxide that brings the two Zn (II) ...