Interaction between Trinuclear Regium Complexes of Pyrazolate and Anions, a Computational Study.

Area of Science:

• Computational Chemistry
• Inorganic Chemistry
• Materials Science

Background:

• Cyclic metal complexes offer unique structural motifs for host-guest chemistry.
• Understanding anion interactions with metal centers is crucial for designing new functional materials.

Purpose of the Study:

• To investigate the binding properties of cyclic (Py-M)3 complexes with halide ions (F-, Cl-, Br-).
• To explore the geometric, energetic, and electronic factors governing anion complexation.
• To determine the maximum number of anions that can be simultaneously held by these complexes.

Main Methods:

• Density Functional Theory (DFT) calculations, specifically Møller-Plesset perturbation theory (MP2).
• Exploration of three distinct anion interaction configurations: planar, apical, and CH group interaction.
• Analysis of energetic profiles, including interaction energies and dissociation barriers.
• Validation of computational findings through a search of the Cambridge Structural Database (CSD).

Main Results:

• Stable 1:1, 1:2, and 1:3 complexes were identified for (Py-M)3 (M = Au, Ag, Cu) with halide anions.
• Complex stability is influenced by specific interaction strengths and Coulombic repulsion.
• Dissociation barriers indicate that (Py-M)3 can stably accommodate up to three anions.
• CSD search confirmed the existence of (Pyrazole-Cu)3 systems with two co-crystallized anions.

Conclusions:

• Cyclic (Py-M)3 complexes exhibit significant potential for simultaneous complexation of multiple halide anions.
• The computational approach provides valuable insights into the factors governing anion binding in these systems.
• Experimental validation supports the theoretical predictions, highlighting the practical relevance of these findings.