Uranyl binary and ternary chelates of tenoxicam Synthesis, spectroscopic and thermal characterization of ternary chelates of tenoxicam and alanine with transition metals

Ternary Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO2(II) chelates with tenoxicam (Ten) drug (H2L1) and dl-alanine (Ala) (HL2) and also the binary UO2(II) chelate with Ten were studied. The structures of the chelates were elucidated using elemental, molar conductance, magnetic moment, IR, diffused reflectance and thermal analyses. UO2(II) binary chelate was isolated in 1:2 ratio with the formula [UO2(H2L)(2)](NO3)(2). The ternary chelates were isolated in 1:1:1 (M:H2L1:L-2) ratios and have the general formulae [M(H2L1)(L-2)(Cl)(n)(H2O)(m)]center dot yH(2)O (M = Fe(III) (n =2, m = 0, y = 2), Co(II) (n = 1, m= 1, y = 2) and Ni(II) (n = 1, m= 1, y = 3)); [M(H2L1)(L-2)](X)(z)center dot yH(2)O (M = Cu(II) (X = AcO, z = 1, y = 0), Zn(II) (X = AcO, z = 1, y = 3) and UO2(II) (X = NO3, z = 1, y = 2)). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl-O groups, while Ala behaves as a uninegatively bidentate ligand coordinated to the metal ions via the deprotonated carboxylate-O and amino-N. The magnetic and reflectance spectral data confirm that all the chelates have octahedral geometry except Cu(II) and Zn(ll) chelates have tetrahedral structures. Thermal decomposition of the chelates was discussed in relation to structure and different thermodynamic parameters of the decomposition stages were evaluated. (C) 2007 Elsevier B.V. All rights reserved.