PROTONATION AND STABILITY-CONSTANTS FOR CO2-CHAIN POLYAMINE 1-AMINO-13-(2-PYRIDYL)-3,6,9,12-TETRAAZATRIDECANE - CRYSTAL-STRUCTURE OF ITS NICKEL(II) COMPLEX(, NI2+, CU2+, AND ZN2+ OF THE OPEN)

The new unsymmetric N-6 ligand 1-amino-13-(2-pyridyl)-3,6,9,12-tetraaz a (aptatd) containing one pyridyl group has been synthesized and chara cterized by EA, IR, and NMR. Its proton association constants (log K-H (n)) and stability constants (log K-ML) for Co(II), Ni(II), Cu(II), an d Zn(II) ions were determined at 298.1 K and ionic strength 0.100 mol dm(-3) (KNO3) in aqueous solution by potentiometry: log K-H(1)=8.80, l og K-H(2)=8.49, log K-H(3)=6.84, log K-H(4)=4.17, log K-H(5)=3.47; log K-ML(Co2+)=18.00, log K-ML(Ni2+)=21.31, log K-ML(Cu2+)=23.62, log K-M L(Zn2+)=15.60. The X-ray structure of its nickel(II) complex [Ni(aptat d)](ClO4)(2) are reported: orthorhombic space group Pbca, a=15.715(1) Angstrom, b=14.280(2) Angstrom, c=19.443(2) Angstrom, V=4363.4 (9) Ang strom(3) with Z=8. The geometry around nickel is a distorted octahedro n with the pyridine nitrogen atom being cis to the nitrogen atom of th e terminal primary amine.