The Gallium(III) and Indium(III) Complexes of Tris(2-mercaptobenzyl)amine and Tris(2-hydroxybenzyl)amine

Tris(2-mercaptobenzyl)amine, S 3 N, and tris(2-hydroxybenzyl)amine, O 3 N, were investigated with In 3+ and Ga 3+ in solution and in the solid state to help interpret the contrasting in vivo behavior of their complexes as diagnostic imaging probes. To this end the protonation and metal binding constants were determined and their similarities and differences with those of analogous ligands, including the O 3 N analogue, are discussed. Seven new crystal structures of Ga(III) and In(III) complexes are also reported: [Ga(S 3 N)], [Ga(S 3 N)(1-Me-imid)], [In(S 3 N)(1-Me-imid)], [In(S 3 N)(DMF)], [Ga(O 3 N)(1-Me-imid)], [Ga(O 3 N)(DMF)], and [In(O 3 N‘)(1-Me-imid) 2 ], where O 3 N‘ is the tris(2-hydroxy-3,5-dimethylbenzyl)amine homologue of O 3 N. The structure of [Ga(S 3 N)] is 4-coordinate, that of [In(O 3 N‘)(1-Me-imid) 2 ] is 6-coordinate, and the remaining structures are 5-coordinate.