Model systems for probing metal cation hydration: the V+(H2O) and ArV+(H2O) complexes

Area of Science:

• Computational Chemistry
• Physical Chemistry
• Spectroscopy

Background:

• Investigating metal-ligand interactions is crucial for understanding chemical processes.
• Vanadium cation complexes with water and argon provide insights into solvation and bonding.
• Infrared photodissociation (IRPD) spectroscopy offers experimental data on these complexes.

Purpose of the Study:

• To computationally investigate the electronic and structural properties of V+(H2O) and ArV+(H2O) complexes.
• To support and interpret experimental IRPD spectroscopy data.
• To determine equilibrium geometries, vibrational frequencies, and binding energies of key states.

Main Methods:

• Employed coupled-cluster methods [CCSD(T)] for high-accuracy electronic structure calculations.
• Calculated equilibrium geometries, harmonic frequencies, and dissociation energies for multiple quintet states.
• Performed anharmonic vibrational analyses and utilized two distinct, high-quality basis sets.

Main Results:

• Identified four low-lying quintet states within a narrow energy range (6 kcal mol(-1)).
• Predicted the ground state for V+(H2O) as 5A1, shifting to 5B1 for ArV+(H2O) upon argon tagging.
• Calculated a theoretical H2O bond angle widening of approximately 4 degrees, less than experimental IRPD findings (9 degrees).

Conclusions:

• Argon tagging significantly influences the electronic ground state of the vanadium-water complex.
• Zero-point vibrational effects, particularly vanadium atom motion, contribute to the observed bond angle.
• Discrepancies between theoretical and experimental bond angle shifts warrant further investigation.