Synthesis, characterisation and crystal structure of a three-dimensional network of an h-bonded Ni (II) Hexametylenetetramine complex

A three-dimensional network of H-bonding nickel (II) hexamethylenetetramine complex has been synthesized and characterised and its structure determined by single crystal X-ray diffraction studies which show that [Ni(H2O)6](HMTA)2Cl32.4H2O crystallizes in the triclinic crystal system with space group PĪ, a = 9.2955(4), b = 9.3187(2), c = 9.3996 Ǻ, α = 119.4160(10), β = 94.4940(10), ɣ = 100.8680(10)º, V =682.47(4) Å3 and z = 1. The nickel atoms are each bonded to six aquo ligands giving an octahedral geometry. The ligand hexamethylenetetramine (HMTA) and chloride ions are bonded to water molecules through hydrogen bonding. Thermal studies show a decomposition pattern corresponding to the loss of the coordinated and uncoordinated water molecules, chloride ions and HMTA ligand in the form of a mixture of gases

Synthesis, characterisation and crystal structure of a cobalt(II)-hexamethylenetetramine coordination polymer

6 páginas, 2 figuras, 3 tablas.A novel one-dimensional zigzag coordination polymer, dinitrodiaqua-bis(hexamethylenetetramine)cobalt(II) was synthesised and characterised, and the structure was determined by single-crystal X-ray diffraction. The compound has a chain structure with each cobalt atom covalently bonded to two nitrate ions, two water molecules and two HMTA molecules, giving a slightly distorted octahedral geometry about the cobalt atom. Each HMTA ligand uses two of its N atoms to bond to two cobalt atoms giving an approximately bent Co–HMTA–Co configuration. Each chain is hydrogen bonded through OH···N and OH···O interactions with neighbouring chains leading to an overall polymer structure. Thermal studies show significant mass loss corresponding to the loss of the coordinated water molecules and the decomposition of both the nitrate ions and the HMTA.Peer reviewe

Synthesis, Characterization, Cyclic Voltammetry, and Biological Studies of Co(II), Ni(II), and Cu(II) Complexes of a Tridentate Schiff Base, 1-((E)-(2-Mercaptophenylimino) Methyl) Naphthalen-2-ol (H2L1)

A novel tridentate Schiff base, 1-((E)-(2-mercaptophenylimino) methyl) naphthalen-2-ol (H2L1), was synthesized by the condensation reaction of 2-hydroxy-1-naphthaldehyde with 2-aminothiophenol in absolute ethanol. The resulting ligand was reacted with Co(II), Ni(II), and Cu(II) ions to obtain tetrahedral CoL1, NiL1, and square planar CuL1 complexes. The Schiff base and its metal complexes were characterized using 1H-NMR, microanalysis, FT-IR, UV-visible, and mass spectroscopy (ESI-MS). All the compounds are soluble in DMSO and DMF. Spectroscopic studies show that the ligand coordinates to the metal center through the azomethine nitrogen, naphthoxide oxygen, and thiophenoxide sulfur to form a tridentate chelate system. Conductance measurements show that these compounds are molecular in solution. Cyclic voltammetry studies show Co(III)/Co(II) and Cu(II)/Cu(I) redox systems to be quasi-reversible involving a monoelectronic transfer while Ni(III)/Ni(II) was irreversible. In vitro antibacterial and antifungal activity against five bacterial strains (Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus faecalis, and Proteus mirabilis) and five fungal strains (Candida albicans, Candida glabrata, Candida tropicalis, Candida krusei, and Candida parapsilosis) showed no antifungal activity but moderate antibacterial activity on E. coli, S. aureus, P. aeruginosa, and P. mirabilis bacterial strains. Antioxidant studies reveal that the ligand and its Cu(II) complex are more potent than Co(II) and Ni(II) complexes to eliminate free radicals