HEXADENTATE N4O2 AMINE PHENOL COMPLEXES OF GALLIUM AND INDIUM

Several linear N4O2 amine phenols based on triethylenetetramine (trien) were prepared and characterized by spectroscopic techniques (H(2)bad = 1,10-bis(2-hydroxybenzyl)-1,4,7,10-tetraazadecane; H(2)Clbad = 1,10-bis(2-hydroxy-5-chlorobenzyl)-1,4,7,10-tetraazadecane; H(2)Brbad = 1,10-bis(2-hydroxy-5-bromobenzyl)-1,4,7,10-tetraazadecane). These amine phenols were prepared by the in situ reduction of the corresponding Schiff bases, which were in turn derived from condensation reactions of trien with the appropriately substituted salicylaldehyde. Characterization of the amine phenols revealed two hydroxybenzyl groups connected to the trien backbone via the terminal primary amine nitrogen atoms. There are six potential sites for coordination to a metal ion: four amine nitrogens and two phenolate oxygens. Acetone adducts, prepared by refluxing the amine phenols in acetone, contained two imidazolidine rings, each of which was formed by the reaction of acetone with one inner and one terminal amine nitrogen. Monocationic metal complexes were obtained from the reactions of Ga3+ and In3+ with the N4O2 amine phenols in the presence of 2 equiv of base (acetate). The molecular structure of [Ga(Brbad)]-ClO4.(CH3)(2)SO (C22H32Br2ClGaN4O7S, MW = 761.6) was determined by X-ray methods: orthorhombic space group Pbca; a = 14.777(4), b = 22.221(5), c = 17.410(7) Angstrom; V = 5717(5) Angstrom(3), Z = 8. The structure was solved by the Patterson method and was refined by full-matrix least squares procedures to R = 4.81%, R(w) = 5.22% for 2230 reflections with F-0(2) greater than or equal to 3 sigma(F-0(2)). Ga3+ was coordinated by four neutral amine nitrogens and two anionic phenolate oxygens to give an N4O2 donor set in a distorted octahedral geometry. The two phenolate oxygen atoms and each pair of sequential N donor atoms were coordinated cis to each other. The perchlorate anion suffers from a 2-fold disorder around a pseudo-3-fold O-Cl axis, and there is a DMSO solvate molecule. H-1 NMR spectral data of the metal complexes showed rigid solution structures for all the Ga and In complexes; no evidence of fluxional behavior was observed at solution temperatures as high as 120 degrees C.