Figure 8.

Formation of precatalytic complexes with HPNP, defined as a metric where at least three distances between the involved oxygen atoms and Zn ion(s) (d₁, d₂, and d₃) are below a defined threshold of 0.25 nm. The distances d₄ and d₅ indicate the active state of such precatalytic complexes, that is, when the water molecule binds to the Zn ion (d₄ < 0.20 nm) and when the nucleophile is ready for the activation (d₅ < 0.25 nm).