The X-ray crystallographic determination of the structure of di-[3-methyl-1(or 5)-phenyl-5(or 1)-p-tolylformazyl]nickel(II)

Abstract

The structure of di-[3-methyl-1 (or 5)-phenyl-5(or 1)-tolylformazyl]nickel(II) has been determined by three-dimensional methods of X-ray analysis. The crystals are triclinic and the apparent space group is P₁ with one molecule in the unit cell. The co-ordination of the nitrogen ligands about the nickel atom is planar but the formazyl rings are buckled out of the central plane. The atoms of the molecule as a whole are so distributed in three dimensions that the aryl groups at positions 1 and 5′(those adjacent to Ni) are separated in nearly parallel planes by distances greater than 2·99 Å. In the crystal, the positions 1 and 5 are not identically situated in space and appear from the calculated electron density to be occupied by phenyl and tolyl groups in the proportion of roughly 45:55. The diffuse character of the observed reflections also suggests the presence of disorder. Since the compound has been shown to be in part resolvable, it is likely that it exists in the crystals studied as a mixture of cis- and trans-isomers, which could be described as (±)-(3-methyl-1-p-tolyl-5-phenylformazyl)(3-methyl-1-phenyl-5-p-tolyl-formazyl)nickel(II), di-(3-methyl-1-phenyl-5-p-tolylformazyl)nickel(II), and di-(3-methyl-1-p-tolyl-5-phenyl-formazyl)nickel(II). The last two are chemically identical, since the pattern of interatomic distances around N(1) is essentially the same as that around N(5), the formazan ring system being stabilised by resonance as expected.