Synthesis, structural characterization and cytotoxic activity of triorganotin 5‐(salicylideneamino)salicylates

Abstract

Six new triorganotin complexes ( 1a – 1c and 2a – 2c ) of 5‐(salicylideneamino)salicylic acid, [5‐(3‐X‐2‐HOC 6 H 3 CH═N)‐2‐HOC 6 H 3 COO]SnR 3 (X = H, 1 ; CH 3 O, 2 ; R = Ph, a ; Cy, b ; CH 2 C(CH 3 ) 2 Ph, c ), have been synthesized by one‐pot reaction of 5‐aminosalicylic acid, salicylaldehyde and triorganotin hydroxide and characterized using elemental analysis and infrared and NMR ( 1 H, 13 C and 119 Sn) spectra. The crystal structures of 1a , 1b , 2a ·CH 3 OH, 2b ·CH 3 OH and 2c ·CHCl 3 have been determined using single‐crystal X‐ray diffraction. In non‐coordinated solvent CDCl 3 , the tin atoms in the complexes are all four‐coordinated. In the crystalline state, these compounds adopt a four‐ or five‐coordination mode. Complex 1a exhibits a 44‐membered macrocyclic tetrameric structure with trigonal bipyramidal geometry around the tin atoms in which the axial positions are occupied by the oxygen atom of carboxylate group of the ligand and the phenolic oxygen atom from the adjacent ligand. The coordination geometry of tin atom in 1b and 2c ·CHCl 3 is a distorted tetrahedron shaped by three carbon atoms of alkyl groups and a carboxylate oxygen atom of the ligand. In 2a ·CH 3 OH and 2b ·CH 3 OH, the tin atom has a distorted trans ‐C 3 SnO 2 trigonal bipyramidal geometry formed by three alkyl groups, a monodentate carboxylate group and a coordinated methanol molecule. The molecules of 2a ·CH 3 OH and 2b ·CH 3 OH are linked via O─H···O hydrogen bonds into a one‐dimensional supramolecular chain and a centrosymmetric R 4 4 (22) macrocycle, respectively. Bioassay results against two human tumor cell types (A549 and HeLa) show the complexes are efficient cytostatic agents and may be explored as potential antitumor drugs.