Uranyl and transition metal chelates of tenoxicam. Crystal structures of trans,trans-[Co(II)(Hten)₂(dmso)₂], trans,trans-[Zn(II)(Hten)₂(dmso)₂] and cis,cis-[UO₂(VI)(Hten)₂(H₂O)] · 2C₂H₅OH

Abstract

The synthesis and characterization of ternary Fe(III)- (1), Co(II)- (2), Ni(II)- (3), Cu(II)- (4), Zn(II)- (5) and UO₂(VI)- (6) chelates with the potent anti-inflammatory drug tenoxicam (H₂ten) and (dl-alanine, Hala) are reported. All complexes are octahedral except Cu(II) and Zn(II) chelates, which are tetrahedral, and U-atoms in the uranyl chelates have a pentagonal-bipyramidal coordination sphere. The ternary Co(II) and Zn(II) complexes dissociate in dmso where orange and yellow crystals of trans,trans-[Co(II)(Hten)₂(dmso)₂] (8) and trans,trans-[Zn(II)(Hten)₂(dmso)₂] (9), respectively, were obtained. Crystallization of the binary uranyl chelate (7) from ethanol afforded the ethanol solvate cis,cis-[UO₂(VI)(Hten)₂(H₂O)] · 2C₂H₅OH (7a). trans,trans-[Co(II)(Hten)₂(dmso)₂] (8) and trans,trans-[Zn(II)(Hten)₂(dmso)₂] (9) crystallize in the monoclinic space group P2₁/n while 7a crystallizes in the triclinic space group . The kinetics of the thermal decompositions for 1, 3, 4, 6 and 7 were studied and the thermodynamic parameters E*, ΔH*, ΔS* and ΔG* evaluated.

Keywords:

• Tenoxicam
• dl-alanine
• Metal chelates
• Vibrational spectra
• Thermal behavior
• X-ray crystal structure

Acknowledgements

The authors are thankful to J. Wagler for his help and useful discussion. N.E.A. El-Gamel is grateful to the Alexander von Humboldt Foundation, Bonn, Germany for financing a 9 month stay at the Inorganic Institute, TU Bergakademie Freiberg, Germany.