However, each of these also gave multiple outliers when validated. Also, of these metals, only nickel was present during preparation of the crystals (in the affinity column used for purification) . The bond lengths are more plausible than for magnesium, since N-Ni bonds are short (1.88 ± 0.03 Å) . However, as noted above, nickel did not fit the electron density, leaving a substantial excess ; further evidence against 2σ BU72 (1b)