Tripodal Iminophenolate Ligand Complexes of Gallium(III), Indium(III), and Thallium(III)

The polydentate tripodal Schiff base ligand H 3 L has been prepared by treating a methanolic solution of tris(aminoethyl)amine and 5‐bromosalicylaldehyde. This ligand, and its complexes with group‐13 metal ions (Ga III , In III , and Tl III ) have been characterized by elemental analysis, NMR spectroscopy, FAB + ‐MS, and X‐ray diffraction analysis. The ligand, not preorganized in the solid state, acts as a hexadentate N 3 O 3 ligand in all cases to form octahedral structures, the apical nitrogen not being involved in the chelation even for the [Tl( L )] complex. NMR studies reveal that the intact and rigid structures of the complexes are maintained in solution. For the [Tl( L )] complex, long‐range thallium isotope effect on the chemical shift (δ H and δ C ) and on the coupling constants ( J Tl‐H and J Tl‐C ) has been observed, confirming a strong and stable bond between Tl III and H 3 L .