Transition metal 2,4,6-trichlorophenolates coordinated by imidazole, N-methylimidazole and 1,2-dimethylimidazole

Abstract

The preparation and properties of a new series of transition-metal trichlorophenolato (tcf) compounds with Ni(II), Co(II), Cu(II) and Zn(II) as metal ions, and imidazoles as nitrogen ligands, are described. Most compounds have the general formula M(tcf) 2(ligand) 2, whereas in a few cases H 2O is also bound in the crystals. The compounds Ni(tcf) 2(imidazole) 6 is exceptional in containing uncoordinated trichlorophenolate ions, apart from the well-known octahedral Ni(imidazole) 2+ 6 cation. The other Co(II) and Ni(II) compounds show electronic spectra that are different from the spectra known for regular six-coordinate and four-coordinate complexes. In fact most spectra agree with five-coordinate metal(II) ions. The Cu(II) ligand field and EPR spectra agree with tetragonal geometry. Magnetic susceptibility measurements of the compounds indicate no magnetic exchange interactions, suggesting a monomeric character of the compounds. This monomeric character is confirmed by a molecular-weight determination in solution, and is further illustrated by the very good solubility in apolar solvents. The infrared spectra of the compounds with 1,2-dimethyl imidazole and with N-methyl imidazole indicate isomorphism between the Co(II) and Zn(II) compounds, whereas the Ni(II) compounds show very similar spectra.