Interaction between K[PtCl₃(piperidin)] and 2‐aminobenzoic acid

Abstract The interaction of K[PtCl 3 (Pip)] ( P1 ) with 2‐aminobenzoic acid (ABz) under varying reaction conditions results in forming three new complexes: cis ‐[PtCl 2 (Pip)(HOOCPhNH 2 ) ( P2 ), [PtCl(Pip)(OOCPhNH 2 )] ( P3 ) and [Pt(Pip)(OOCPhNH 2 ) 2 ] ( P4 ). Complexes P2 and P3 are obtained at the molar ratio of P1 : ABz being 1:1 with pH = 4–6. When the reaction time increases, the yield of their formation increases, but the molar ratio of P2 : P3 almost unchanges. However, this ratio decreases when the pH increases; at pH = 8–9, only complex P3 is formed with a yield of 82% after 10 h. When increasing the molar ratio of P1 :ABz to 1:2.2 at pH 8–9, P4 is the sole product, with a 90% yield after 15 h, and P3 serving as a stable intermediate. Structural characterization of P2 , P3 , and P4 was performed using Pt analysis, IR, 1 H NMR, EDX, and ESI‐MS (for P4 ), complemented by DFT calculations. In P2 , ABz coordinates to Pt(II) via the N atom in the cis position relative to Pip. In P3 and P4 , ABz undergoes dehydrogenation at the COOH group (OOCPhNH 2 ) and coordinates to Pt(II) through both COO − and NH 2 groups, with two N atoms in trans positions. In P4 , the second OOCPhNH 2 ligand binds via the O atom of COO − in the cis position relative to Pip. In addition, the calculations determined reaction paths, transition states for the formation of P2 , P3, P4 , and elucidated the influence of time and pH on the molar ratio of P2 : P3 and the efficiency of P4 formation.