Solution study and crystal structure of a pentacoordinate zinc(II) complexwith N,N '' bis-(2-hydroxybenzyl)diethylenetriamine

The stability constants of Zn(II) complexes with N,N " -bis-(2-hydroxybenzy l)-diethylenetriamine(H2L) were determined by potentiometric pH titration a t 25 degreesC and at 0.1 M KNO3 ionic strength. A neutral complex ZnL was s ynthesized. In addition to IR, and H-1 NMR spectra, its structure was estab lished by single crystal X-ray diffraction. The crystal is orthorhombic, of space group Pbca, with cell constants a = 17.865(4), b = 20.079(4), c = 9. 598(2) Angstrom, z = 8 and D-c = 1.461g.m(-3). The structure was solved and refined to R = 0.049 (R-omega = 0.054). The coordination geometry around t he zinc ion is trigonal-bipyramidal with a large distortion, exhibiting two nonequivalent phenolates.