Synthesis, structures and biological properties of nickel(II) phthalates with imidazole and its derivatives

Abstract Four new nickel(II) phthalate compounds: mononuclear complexes [Ni(Im)] 6 (Pht)·H 2 O ( 1 ), [Ni(Pht)(Im) 3 (H 2 O) 2 ]·H 2 O ( 2 ) and [Ni(Pht)(2-MeIm) 3 (H 2 O) 3 ]·H 2 O ( 3 ), and coordination polymer [Ni(Pht)(4-MeIm) 2 (H 2 O)] n ( 4 ) (where Pht = dianion of o -phthalic acid, Im = imidazole, 2-MeIm = 2-methylimidazole, 4-MeIm = 4-methylimidazole) have been synthesized. The complexes 1 – 4 were characterised by elemental analysis, IR data, thermogravimetric, and X-ray diffraction analyses. X-ray analysis shows that the asymmetric unit of 1 consists of [Ni(Im)] 6 2+ cation, Pht 2− anion and solvate H 2 O molecule. The phthalate dianion does not take part in coordination to metal ion. The cations, anions and water molecules are linked via N–H ⋯ O and O–H ⋯ O interactions forming 2D hydrogen-bonded networks. The structures of 2 and 3 are similar to other mononuclear Ni(II) phthalate complexes where Pht 2− anions act as monodentate ligands and uncoordinated carboxylate oxygen atoms participate in the formation of hydrogen bonded double-chains. The structure of 4 consists of [Ni(4-MeIm) 2 (H 2 O)] building units connected by phthalate ions to form helical chains. The complexes 1 – 4 were tested for their ability to increase the biosynthesis of enzymes.