Nevertheless, an in depth investigation in the geometry at the
nickel(IV) centre gave some unexpected results. The tetra-coordinated
nickel centre may be idealised as tetrahedral at first glance,
but it is actually severely distorted, containing four wide (122–
129) and two narrow (80–81) angles instead of six angles at
109.5. The DFT-optimised (B3LYP/6-31G⁄⁄/LACVP level) geometry
highly agreed with the experimental results. This is perhaps unsurprising
due to the requirements of the five-membered rings, and
the steric demand exerted by the two ligands. Curiously, when
the calculations were applied to the sterically less-challenged, simple
‘‘parent’’ nickelaspirocyclononane Ni(C4H8)2 complex, the geometry at the nickel centre is similarly distorted as the synthesised example.