COMPLEXES WITH AMBIDENTATE LIGANDS DERIVED FROM PYRIDINE AND PYRIMIDINE .1. CYCLIC NICKEL(II) COMPLEXES

In a series of hexacoordinated nickel(II) complexes, prepared from thio-, sulphinyl, and carbonyl derivatives of pyridine and pyrimidine, the endocyclic N-atom was always the preferred basic site; the sulphinyl O-atom was also a donor centre, forming 5-membered heterocycles, whereas the carbonyl O-atom did not bond to the metal. Alkylthio derivatives did not react, unlike thiolate anions, which form N, S-bonded 4-membered rings. On the other and 2,2′-bis(pyridyl)ketone bonded exclusively through the N-atoms, forming 6-membered cycles. © 1990 Chapman and Hall Ltd.