Protonation and Stability Constants for Co2+, Ni2+, Cu2+, and Zn2+ of the Open-Chain Polyamine 1-Amino-13-(2-pyridyl)-3,6,9,12-tetraazatridecane. Crystal Structure of Its Nickel(￥±) Complex

摘要

The new unsymmetric N6 ligand 1-amino-13-(2-pyridyl)-3,6,9,12-tetraazatridecane (aptatd) containing one pyridyl group has been synthesized and characterized by EA, IR, and NMR. Its proton association constants (log KHn) and stability constants (log KML) for Co(ケ), Ni(ケ), Cu(ケ), and Zn(ケ) ions were determined at 298.1 K and ionic strength 0.100 mol dm-3 (KNO3) in aqueous solution by potentiometry: log KH1=8.80, log KH2=8.49, log KH3=6.84, log KH4=4.17, log KH5=3.47; log KML(Co2+)=18.00, log KML(Ni2+)=21.31, log KML(Cu2+)=23.62, log KML(Zn2+)=15.60. The X-ray structure of its nickel(ケ) complex [Ni(aptatd)](ClO4)2 are reported: orthorhombic space group Pbca, a=15.715(1) ∈, b=14.280(2) ∈, c=19.443(2) ∈, V=4363.4 (9) ∈3 with Z=8. The geometry around nickel is a distorted octahedron with the pyridine nitrogen atom being cis to the nitrogen atom of the terminal primary amine.