[Be(NH₃)₁₆]^{[2] +} Microsolvation: Structure, Energetics, and Temperature Effects

Area of Science:

• Computational Chemistry
• Quantum Chemistry
• Materials Science

Background:

• Beryllium ion (Be2+) coordination chemistry is crucial for understanding ion-ligand interactions.
• Ammonia (NH3) is a fundamental ligand in coordination chemistry, with its interactions with metal cations being extensively studied.
• Gas-phase clusters provide a simplified model for studying solvation and noncovalent interactions.

Purpose of the Study:

• To investigate the gas-phase structural, energetic, and thermal properties of the [Be(NH3)16]2+ cluster.
• To elucidate the role of electrostatic interactions and ligand arrangement in cluster stability.
• To analyze the cooperative effects of Be2+-N coordination and N-H...N hydrogen bonds.

Main Methods:

• * Ab initio calculations using the MP2/6-311++G** level of theory.
• * Analysis of isomer stability based on electrostatic interactions and ligand spatial arrangement.
• * Quantum Theory of Atoms in Molecules (QTAIM) analysis to characterize bonding.

Main Results:

• * The [Be(NH3)16]2+ cluster exhibits strong binding, with an asymptotic binding energy of -32.2 kcal/mol.
• * A compact and stable first solvation shell is observed, with weaker secondary interactions.
• * Temperature-dependent studies show entropy plays a key role in thermal stabilization.
• * QTAIM analysis confirms the presence of Be2+-N coordination bonds and N-H...N hydrogen bonds.

Conclusions:

• * Cooperative noncovalent interactions, including Be2+-N coordination and N-H...N hydrogen bonds, significantly enhance the stability of the [Be(NH3)16]2+ cluster.
• * The findings provide insights into the fundamental principles governing ion-ligand interactions in gas-phase clusters.
• * This study contributes to a deeper understanding of solvation phenomena and the factors influencing cluster formation and stability.