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 = 2-hy droxy-5-chlorobenzyl)-1,4,7,10-tetraazadecane; H(2)Brbad = 2-hydroxy-5 -bromobenzyl)-1,4,7,10-tetraazadecane). These amine phenols were prepa red by the in situ reduction of the corresponding Schiff bases, which were in turn derived from condensation reactions of trien with the app ropriately substituted salicylaldehyde. Characterization of the amine phenols revealed two hydroxybenzyl groups connected to the trien backb one via the terminal primary amine nitrogen atoms. There are six poten tial sites for coordination to a metal ion: four amine nitrogens and t wo 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 re actions of Ga3+ and In3+ with the N4O2 amine phenols in the presence o f 2 equiv of base (acetate). The molecular structure of [Ga(Brbad)]-Cl O4.(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 lea st 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 coordin ated 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 s olvate molecule. H-1 NMR spectral data of the metal complexes showed r igid 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.