The crystal structure of tetramethylenedinitramine(diaquo)nickel(II)

Abstract

The crystal structure of the green complex formed by nickel with tetramethylenedinitramine has been determined by three-dimensional X-ray crystal structure analysis. In a monoclinic unit cell, a= 15·35, b= 5·51, c= 12·73 Å, β= 94·5°, space group l2/a, there are four units of formula Ni[(CH₂)₄(NNO₂)₂]2H₂O.

The complex forms polymeric chains, parallel to the a-axis, and lined by hydrogen-bonds to neighbouring chains. Each ligand molecule spans two nickel atoms, both nitramine groups being co-orinated. Each nickel atom is 6-co-ordinated, the ligands being two water molecules (Ni–O = 1·99 Å) and the nitramine groups of two different molecules. A nitramine group acts as a chelate ligand; one oxygen atom (Ni–O = 2·16 Å) and the amino nitrogen atom (Ni–N = 2·23 Å) are co-ordinated so that, with the nickel atom and the other nitrogen atom, a four-membered ring is formed. The N–Ni–O angles in the four-membered rings are 58°, and the other angles at the nickel atom range from 90 to 105°.

Within the ligand the bond lengths are N–O (co-ordinated)= 1·36, N–O = 1·32, N–N = 1·24, N–C = 1·57, C–C = 1·47, and C–C (central)= 1·56 Å. Hydrogen atoms were not located.