Electron Diffraction Investigation and Magnetic Measurements on Nickel (II) Bisacetylacetone

Abstract

SOME nickel(II) complexes are paramagnetic, whereas others are diamagnetic. These complexes are classified as tetrahedral or planar on the basis of magnetic measurements with the aid of Pauling's theory¹ relating the geometric configuration of ligands, various arrangements of electrons in orbitals, and the resulting magnetic moments. Nickel(II) bisacetylacetone is known to be paramagnetic², and for this sole reason is believed to be an example of a tetra-co-ordinated complex having a tetrahedral structure. A more direct method of investigation has recently been undertaken by Bullen³, who, using X-ray diffraction, showed that there are three nickel atoms in an asymmetric unit, the three atoms being very nearly collinear. He argues that with trinuclear molecules the possibility of octahedral co-ordination of the nickel atoms must be taken into account, and that it is not simply a choice between tetrahedral and square co-ordination. We considered it desirable to elucidate the structure of a free molecule of this compound, and have undertaken its investigation by electron diffraction.