A study of the co-ordination behaviour of various 2-pyridyl-ketones. Part V. The interaction of di-(2-pyridyl)ketone with salts of cobalt, nickel and iron

Abstract

New compounds of cobalt(II), cobalt(III), iron(II) and iron(III) with di-(2-pyridyl)ketone (pyCOpy) are reported which in some cases constitute further examples of the metal promoted reaction of the ligand carbonyl group with water or alcohols. Under some circumstances it is difficult to prevent reaction of the carbonyl group whereas in other cases the group is very resistant to attack. A third group of systems exist in which the aquation or hemi-acetal formation is readily reversible. The new compounds reported are characterized by elemental and spectroscopic analysis. In one case an authentic example of co-ordination via the carbonyl group is found and in another the ligand is present as the ketal pyC(OEt) 2py. The ligand field strength (Δ) of di-(2-pyridyl)ketone varies with the steric environment; in a complex such as [Fe(pyCOpy) 2(NCS) 2], which is shown to be cis, the value of Δ is comparable with that of 1,10-phenanthroline whereas it is considerably less in a compound such as [Co(pyCOpy) 2 (pyC(OEt)(OH)py)](ClO 4) 2.