A higher yield synthesis of N,N'-bis(2-pyridylmethyl)-1,3-diaminopropane-N,N'-diacetic acid (H(2)bppd) and its complexation of trivalent metal ions (Al(III), Ga(III), In(III)) and selected lanthanides (Ln(III)) are reported. H(2)bppd and the metal-bppd(2-) complexes, isolated as hexafluorophosphate salts, were characterized by elemental analysis, mass spectrometry, IR, and H-1 and C-13 NMR spectroscopy. [Ga (bppd)]PF6, [Ga(C19H22N4O4) PF6, was crystallized as colorless needles by slow evaporation from anhydrous methanol; its molecular structure was solved by direct X-ray crystallography methods. The compound crystallized in the monoclinic space group P2(1)/c, with a = 9.6134(2) angstrom, b = 20.2505(4) angstrom, c = 11.6483(3) angstrom, beta = 97.520(1)degrees, and Z = 4. Ga is coordinated in a distorted octahedral geometry provided by a N4O2 donor atom set with cis-monodentate acetate groups and cis-2-pyridylmethyl N atoms. Quantum mechanical calculations were performed for the three possible geometric isomers of a pseudo-octahedral metal-bppd(2-) complex with five different metal ions. The results indicate, that in aqueous solution, the stability of the trans-O,O isomer is similar to that of the cis-O,O; cis-N-py,N-py isomer but is greater than that of the trans-N-py,N-py isomer. Calculations for a six-coordinate La(III)-bppd(2-) complex converge to a structure with a very large N-py-La-N-py bond angle (146.4 degrees), a high metal charge (2.28 au), and a high solvation free energy (-79.4 kcal/mol). The most stable geometric arrangement for bppd(2-) around the larger La(III) is best described as an open nestlike structure with space available for additional ligands. IR spectroscopy was used to investigate the nature of the H(2)bppd-metal complexes isolated in the solid state and the binding modes of the carboxylate functionalities. The spectra indicate that fully deprotonated [M(bppd)](+) complexes as well as partially protonated complexes [M(Hbppd)Cl](+) were isolated. The H-1 and C-13 assignments for H(2)bppd and metal bppd(2-) complexes were made on the basis of 2D COSY, NOESY, and H-1-C-13 HSQC experiments, which were used to differentiate among the cis (C-1 symmetry) and the two trans (C-2 symmetry) isomers.