Ligand‐Exchange Processes on Solvated Zinc Cations: Water Exchange on [Zn(H₂O)₄(L)]²⁺⋅2 H₂O (L=Heterocyclic Ligand)

Abstract

The water-exchange mechanisms of [Zn(H(2)O)(4)(L)](2+).2H(2)O (L=imidazole, pyrazole, 1,2,4-triazole, pyridine, 4-cyanopyridine, 4-aminopyridine, 2-azaphosphole, 2-azafuran, 2-azathiophene, and 2-azaselenophene) have been investigated by DFT calculations (RB3LYP/6-311+G**). The results support limiting associative reaction pathways that involve the formation of six-coordinate intermediates [Zn(H(2)O)(5)(L)](2+).H(2)O. The basicity of the coordinated heterocyclic ligands shows a good correlation with the activation barriers, structural parameters, and stability of the transition and intermediate states.

Tuning Dynamic Mechanical Response in Metallopolymer Networks through Simultaneous Control of Structural and Temporal Properties of the Networks

“…Ligand substitution in transition metal complexes is influenced by their electronic configuration and coordination number of the metal centers. The ligand exchange in four-coordinate tetrahedral complexes, such as Zn­(Imz) 4 2+ and Cu­(Imz) 4 2+ , proceeds mainly through an associative mechanism for which the rate of exchange increases as the concentration of free ligand increases. ,− For both L-ICP–Cu and L-ICP–Zn, at high L/M ratio (i.e., low metal ion content) the cross-linked junctions can rapidly exchange due to the relatively high concentration of uncoordinated imidazole moieties on the polymer chains. Accordingly, an uncoordinated imidazole moiety is not merely a dangling chain with no contribution to the mechanical properties.…”