Trigonal prismatic versus octahedral co-ordination. Part 2. X-Ray structure determinations of manganese(II), cobalt(II), and nickel(II) complexes of intermediate geometry derived from the ligand 1,1,1-tris-(pyridine-2-aldiminomethyl)ethane

Abstract

X-Ray diffraction studies on three isomorphous divalent metal complexes (Mn, Co, and Ni) of the ligand 1,1,1-tris(pyridine-2-aldiminomethyl)ethane are reported. The sexidentate ligand has an approximate trigonal axis and defines co-ordination geometries at the metal ions which are considerably distorted from octahedral. Measures of the twisting of the ligand about the trigonal axis together with other structural parameters allow the complexes to be described in terms of a distortion towards a trigonal prismatic donor set which varies in the order Fe^II < Ni^II < Co^II < Zn^II < Mn^II. Such an order is shown to be compatible with the electronic configurations and ionic radii of the complexed metal ions.