Unusual cis/trans isomerism in octahedral nickel(II) complexes with 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid) as a ligand

Abstract

Nickel(II) ion reacts with 1,4,8,11-tetraazacyclotetradecane-1,8-bis(methylphosphonic acid) (H4L1) at room temperature with formation of cis-[Ni(L1)]2- complex. The complex was crystallised in several forms in dependence on conditions of isolation (temperature, pH, solvent mixture).

Crystal structures of cis-O,O-[Ni(H2L1)] (1), cis-O,O-[Ni(H2L1)]?2H2O (2), cis-O,O-[Ni(H3L1)]Cl?H2O (3) and cis-O,O-[Ni(H4L1)]Cl2?2H2O (4) were determined by X-ray diffraction.

Keywords

• Azacrown compounds
• Cyclam
• Phosphonates
• Nickel(II) complexes
• cis/trans Isomerism
• Conformation analysis
• Crystal structure determination
• X-ray diffraction
• Macrocyclic ligands