Importantly, the drastic expansion/contraction of the space can be precisely and reversibly triggered by the addition/removal of Al(C6F5)3. In addition, this rotational transformation alters the shape of the space around the Ni center, as clearly confirmed by the comparison of both the %Vbur(NE) and %Vbur(SE) values of 2a and 3a. Å; bond radii scaled by 1.17; mesh spacing 0.05; H atoms are omitted) based on the structural parameters obtained from the SC-XRD analysis.