Coordination-Driven Scrambling in Tricopper(I) Clusters: Thermodynamic Insights into Dynamic Assembly

Controlling product distributions in multicomponent self-assembly remains a central challenge in coordination chemistry, particularly when exchange occurs at the level of pre-organized metal-ligand fragments. β-Thioketiminato tricopper(I) clusters, [LCu]3, define a rare class of metal-cluster-based dynamic combinatorial systems that redistributes Cu-ligand coordination units rather than free ligand exchange. Mixing homoleptic precursors [LACu]3 (A3) and [LBCu]3 (B3) generates a dynamic library of heteroleptic species (A2B and AB2b), those distributions follow binomial statistics across varying initial compositions. Variable-temperature NMR (VT-NMR) establishes rapid, reversible exchange and reveals temperature-dependent equilibration. Non-linear Van't Hoff analysis demonstrates that increasing temperature enhances the entropic stabilization of heteroleptic assemblies. In contrast, lower temperatures promote enthalpy-driven homoleptic stabilization with a thermodynamic regime crossover near 275 K. Complementary DFT calculations suggest that low-temperature scrambling proceeds through enthalpy-biased redistribution involving dicopper fragments and monomeric intermediates. In comparison, higher temperatures enable more entropy-driven pathways through solvation-assisted dissociation. These results show that simplified multinuclear clusters provide a model for studying thermodynamic control of entropy-driven self-assembly and tunable self-sorting in metal-cluster systems.