INHIBITION OF REACTIVITY IN SQUARE-PLANAR COMPLEXES OF NI(II) WITH 2,6-DISUBSTITUTED PYRIDINES - NOVEL EFFECT IN STERIC HINDRANCE

The reaction of Ni(II) halides or thiocyanate with doubly hindered substituted (2,6-dimethyl, 2,3,6-trimethyl-, 2,4,6-trimethyl-) pyridines, when carried out under controlled conditions to prevent hydrolysis, yields a series of crystalline complexes of the general formula [NiX2L2] (X = Cl, Br, I, NCS), having a trans-planar geometry. These complexes are unique among the many known Ni(II)-pyridine derivatives in that they are inert to exchange with other potential ligands, including water, and are not attacked even by strong mineral acids. The reasons for this inertness are discussed in terms of the electronic and steric properties of the complexes. © 1979.