Synthesis and coordination properties of new macrocyclic ligands: equilibrium studies and crystal structures
Abstract
The synthesis and characterization of two new macrocyclic K1
= 10.93, log
K2
= 9.70, log
K3
= 8.79, log
K4
= 8.05, log
K5
= 6.83, log
K6
= 2.55). All metal ions form stable mono- and dinuclear complexes: log
KMLH−1
= 25.61 for Cu(II), 15.37 for Zn(II), 12.58 for Cd(II) and 13.79 for Pb(II); log
KM2LH−1
= 31.61 for Cu(II), 23.38 for Zn(II), 24.49 for Cd(II) and 23.68 for Pb(II). All these dinuclear species show a great tendency to add the OH− group: the equilibrium constant for the addition reaction was found to be log
KM2LH−1OH
= 4.77 for Cu(II), 5.66 for Zn(II), 2.8 for Cd(II) and 3.18 for Pb(II). In the case of Ni(II), kinetic inertness prevents the possibility of solution studies. The dinuclear solid adducts [Ni2H−1L(N3)3]·EtOH and [Cu2H−1L(N3)](ClO4)2 were characterized by