The reactions are reported of NbX 5 (X= Cl, Br), TiCl 4 and Ti(O i Pr) 4 with a selection of carboxylic acids exhibiting a known biological role, in a chlorinated solvent. The reactions of NbX 5 with acetylsalicylic acid (aspirin) proceeded with selective deacetylation of the organic reactant and formation of the salicylate complexes NbX 4 (C 7 H 5 O 3 ) (1a, X = Cl; 1b, X = Br) in 60-65% yields. NbCl 5 reacted with diclofenac and ethacrynic acid (EA-CO 2 H) to give NbCl 3 [κ 3 O,O,N -O 2 CCH 2 (C 6 H 4 )NC 6 H 3 Cl 2 ], 2 (80% yield), and NbCl 4 (O 2 C-EA), 3 (72% yield), respectively. Ti(O i Pr) 4 reacted with ethacrynic acid giving Ti(O i Pr) 2 (O 2 C-EA) 2 , 4, in 74% yield, as a mixture of two isomers. All the products were characterized by means of analytical and spectroscopic methods, moreover DFT studies were carried out to give insight into structural features.