Metal Complexation of Deferasirox Derivatives: A Solid State and Equilibrium Study

Complexation of deferasirox (4-[3,5-bis(2-hydroxyphenyl)-1,2,4-triazol-1-yl]benzoic acid, H 3 L B ) and its decarboxylated derivative (H 2 L A ) with Ru(III), Os(IV), Co(III) and Ga(III) was studied. These complexes are expected to show anticancer potential. Formation of 1:2 octahedral complexes via a (O,N,O) tridentate coordination of the ligands was detected to yield K 3 [Ru(L B ) 2 ], K[Co(L A ) 2 ], K 3 [Co(L B ) 2 ] and (guanidinium)Na 2 [Ga(L B ) 2 ], respectively. The molecular structure by single crystal X-ray diffraction also confirmed the octahedral geometry for K[Co(L A ) 2 ].2Pr i OH. Unprecedented formation of K 2 [Os VI L B (O) 2 (OH)] having a tridentate (O,N,O) coordinating ligand, two oxo groups and an a hydroxide ion in the coordination sphere of the metal ion of +6 oxidation state was also found. Simple synthesis and solid state structure of the novel disulfonated derivatives of L B , and L A , (L D and L C , respectively, with excellent water solubility) is also presented. Interaction of Ga(III) with H 5 L D and H 4 L C resulted in the formation of 1:1 and 1:2 complexes with different protonation degree in aqueous solution among them [Ga(L D ) 2 ] 7– and [Ga(L C ) 2 ] 5– being the major species under physiologically relevant conditions.