Cadmium(II) complexation by a series of triazacycloalkanes ([x]aneN3, x = 9–12). An equilibrium and structural study
作者:Leverett J. Zompa、Hilda Diaz、T.N. Margulis
DOI:10.1016/0020-1693(94)04380-e
日期:1995.4
The complexation of Cd(II) by a series of triazacycloalkanes, ([x]aneN(3), x = 9-12), has been studied in 0.10 mol dm(-3) KNO3 aqueous solution at 298.2+/-0.1 K. Stability constants (beta(CdL)) for the complexes decrease in magnitude with increasing number of atoms in the ligand ring, and are several orders of magnitude smaller than corresponding beta(ZnL) values. Two complexes [Cd-2([9]aneN(3))(2)(mu-Cl)(2)Cl-2] (1) and [Cd-2([11]aneN(3))(2)a(mu-Cl)(2)Br-2] (2) were synthesized, and the structures determined by X-ray crystallography. Complex 1 crystallizes in the triclinic space group P1, with a = 7.657(2), b = 7.741(2), c = 17.750(2) Angstrom, alpha = 90.13(3), beta = 94.65(3), gamma = 90.76(3)degrees and V = 1048.5(5) Angstrom(3) for Z = 2. Complex 2 crystallizes in the monoclinic space group P2(1)/c with a = 8.144(2), b = 8.469(2), c = 18.480(4) Angstrom, beta = 97.62(3)degrees and V = 1263.3(6) Angstrom(3) for Z = 2. Both structures contain bridging di-mu-chloro groups separating six-coordinate Cd(II). Each Cd(II) is also bonded to a tridentate ligand and Cl (structure 1) or Br (structure 2).