LAUSR

Abstract Two new mixed ligand Co(II) complexes of the non-steroidal anti-inflammatory drug indomethacin (indo), viz. [Co(indo)2(H2O)4]∙2H2O;CI-1, [Co(indo)(imi)2Cl];CI-2, (where indo = indomethacin [1-(4-chlorobenzoyl)-5-methoxy-2-methyl-1Hindole-3-acetic acid)], and imi = imidazole), have been synthesized and characterized. The monodentate coordination of the carboxylato oxygen of indomethacin ligand in the complexeswas confirmed from FTIR studies, while their stability and decomposition pattern were studied using TG analysis. CI-2 exhibited higher stability than CI-1, which is attributed to the absence of lattice solvents in CI-2. The X-ray structural analysis of the complexes shows that they both consist of monomeric units which crystallize in the monoclinic P21/C space group. CI-1 consists of Co(II) ion in hexa-coordination with four water molecules and two trans indomethacin ligands, having a slightly distorted octahedral geometry. CI-2 consists of tetracoordinate Co(II) with two imidazole ligands, a monodentate indomethacin ligand, and one chloride ligand, forming a slightly distorted tetrahedral geometry. The crystal packing of CI-1was dominated by O-H•••O, C-H•••O, and C-H∙•••π interactions.The lattice water molecule outside its coordination sphere led to intermolecular hydrogen bond formation (i.e., O-H•••O interaction). CI-2 was dominated by N-H•••O, N-H•••Cl, C-H•••Cl, and C-H•••π interactions.