Electrospray mass spectrometry and X-ray crystallography studies of divalent metal ion complexes of tris(2-pyridylmethyl) amine

Coordination complexes of tris (2-pyridylmethyl) amine (TPA) were prepared and characterized including [Zn(TPA)X]ClO4 (X=Cl, Br, I), [Cu(TPA)Br]ClO4, [Cd(TPA)Br-2], [Cd(TPA)(H2O)(NO3)]NO3, [Cd(TPA)I-2], [Co(TPA)Cl-2], [Fe(TPA)Cl-2] and [Mn(TPA)Cl-2]. The solid-state structures of Zn(TPA)ClClO4 (monoclinic space group, P2(1)/c; a = 14.733(3), b = 9.408(2), c = 29.722(4) Angstrom, beta=90.65(1)degrees; V=4119(1) Angstrom(3); Z=8), Zn(TPA)IClO4 (triclinic space group, P (1) over bar; a=14.435(3), b=17.069(4), c=9.745(2) Angstrom, alpha=100.36(2), beta=91.40(2), gamma=114.62(1)degrees; V=2134(2) Angstrom(3); Z=4) and Cu(TPA)BrClO4 (monoclinic space group, P2(1)/c; a=14.555(3), b=9.519(2), c=30.024(3) Angstrom, beta=91.66(1)degrees; V=4158(1) Angstrom(3); Z=8), contain trigonal bipyramidal metal ions with halide coordinated in an apical position. The X-ray structure of [Cd(TPA)(H2O)(NO3)]NO3 (monoclinic space group, P2(1)/n; a=15.415(4), b=9.333(2), c=17.429(4) Angstrom, beta=99.39(2)degrees; V=2474(2) Angstrom(3); Z=4) contains a seven-coordinate cadmium ion including a bidentate nitrate anion and a water molecule as ligands. The X-ray structure of [Cd(TPA)I-2] (monoclinic space group, P2(1)/n; a=10.383(2), b=13.813(2), c=15.391(1) Angstrom, beta=106.07(1)degrees; V=2121.1(5) Angstrom(3); Z=4) contains a cadmium ion with an approximately octahedral geometry. In this structure, the TPA ligand is conformationally distorted in order to accommodate the octahedral coordination geometry. The convenient new technique, electrospray mass spectrometry (ESI-MS), provided mass spectra consistent with X-ray and spectroscopic data. Mass analysis of solutions containing added competing anions was also consistent with solution data.