Crystal structure of tris(2-hydroxy-3,5-dimethylbenzyl)amine.

(H3tdmba, Fig. 1), is a tripodal quadridentate ligand having one tertiary amine-N and three phenolate-O donor atoms. Recently, we have reported the solvent extractive mutual separation of the Group 13 metals (aluminum, gallium and indium) using the above ligand, which showed high extraction selectivity of Ga3+ to Al3+ and In3+.1 It is of interest and significant to study the crystal structure of the novel ligand for the evaluation of the mutual selectivity of the Group 13 metals in the extraction systems. In this paper, we report on the structure of the metalfree tripodal NO3-donor type ligand. H3tdmba was prepared by a modification of the literature method.2 A mixture of 2,4-xylenol (0.30 mol), hexamethylenetetramine (25 mmol) and 36% formaldehyde (0.15 mol) was refluxed at 180 ̊C for 6 h. The yellow mixture was cooled to room temperature, dissolved in diethylether, and then hexane was added to the solution in excess to precipitate crude product. This was recrystallized from diethylether/methanol to give a colorless single crystal of product suitable for X-ray diffraction. The crystal and experimental data are summarized in Table 1. Lorentz and polarization corrections were applied. An absorption correction based on Ψ-scans was introduced. All non-hydrogen atoms were refined anisotropically. The hydrogen atoms were determined from difference Fourier syntheses and were refined isotropically, but the hydrogen atoms of three hydroxyl groups were not refined. The positional parameters and temperature factors for non-H atoms are listed in Table 2. 913 ANALYTICAL SCIENCES JULY 2001, VOL. 17 2001 © The Japan Society for Analytical Chemistry