COMPLEXES OF TRIVALENT METAL-IONS WITH POTENTIALLY HEPTADENTATE N4O3 SCHIFF-BASE AND AMINE PHENOL LIGANDS OF VARYING RIGIDITY

{The synthesis and characterization of several potentially heptadentate N4O3 Schiff bases and amine phenols, as well as a series of their mononuclear and dinuclear complexes with indium and the lanthanides are reported. Schiff bases containing imidazolidine rings were the products of the known condensation reaction of triethylenetetramine with 3 equiv of 5-substituted salicylaldehydes to form H(3)api (5-H-substituent), H(3)Clapi (5-Cl-substituent), or H(3)Brapi (5-Br-substituent); KBH4 reduction of these Schiff bases gave the appropriate isomeric N4O3 amine phenols H-3(1,2,4-btt) and H-3(1,1,4,-btt), as well as an acetone adduct, H-3(1,2,4-ahi). The Schiff bases reacted with 1 equiv of a lanthanide (Ln(3+)) nitrate to produce mononuclear nine-coordinated [Ln(H(3)Xapi)-(NO3)(3)] complex wherein the ligand adopts a tridentate capping coordination mode, whereas the amine phenols formed mononuclear seven-coordinate complexes with the lanthanides and indium; homodinuclear complexes [LnL]2 were also obtained with the Schiff bases. The X-ray structures of the Schiff bases H(3)api and H(3)Clapi, the mononuclear amine phenol complexes Yb(1,2,4-btt) . 0.5CH(3)OH and In(1,1,4-btt), and the homodinuclear Schiff base complex [La(Brapi)](2) . 2CHCl(3) have been determined. Crystals of H(3)api (C27H30N4O3) are monoclinic, space group P2(1)/a