Synthesis and characterisation of complexes formed between the ligand tris(2-pyridylmethyl)amine and the Group III metals gallium and thallium

Reactions of the Group III metals, gallium and thallium, with the ligand tr is(2-pyridylmethyl)amine (TPA) leads to the formation of 1:1 metal to ligan d complexes, but not the simple 1:1 complexes observed in the reactions bet ween the Group I and II metals with TPA. One such complex, [Ga(TPA)(OH)](2) (Cl)(4). 4H(2)O .2.956MeOH (1), has been structurally characterised and fou nd to have a dimeric structure resulting from hydroxy bridging. The crystal structure of the thallium complex was also determined and was found to be [TI(TPA)](2)[H3O][NO3](3) (2), consisting of two different [TI(TPA)](+) cat ions, one of which was disordered. The essential difference between the two cations is that one contains a four co-ordinate thallium cation while the second contains a seven co-ordinate thallium. cation as a result of bonding to the three nitrate anions. (C) 2001 Elsevier Science BN. All rights rese rved.