Vibrational spectroscopy of small hydrated CuOH+ clusters

Area of Science:

• Inorganic Chemistry
• Physical Chemistry
• Catalysis Science

Background:

• Copper hydroxide complexes are crucial in copper-catalyzed water oxidation reactions.
• Understanding ligand interactions within these complexes is key to optimizing catalytic efficiency.
• Previous models of copper ion coordination in water may not fully represent these hydroxide-centered systems.

Purpose of the Study:

• To investigate the structural and coordination properties of D2-tagged copper hydroxide-water clusters (CuOH(+)(H2O)n).
• To elucidate the role of coordinated water molecules in the solvation shell of copper hydroxide ions.
• To compare experimental vibrational spectra with theoretical calculations to validate computational methods.

Main Methods:

• Generation of D2-tagged CuOH(+)(H2O)n clusters using electrospray ionization.
• Probing vibrational spectra in the OH stretch region via cryogenic ion vibrational spectroscopy.
• Analysis of spectral features to determine geometric and coordination structures.

Main Results:

• The copper center in CuOH(+)(H2O)3 clusters exhibits a distorted square planar geometry.
• Coordination resembles Cu(2+)(H2O)n (four ligands) rather than Cu(+)(H2O)n (two ligands).
• No significant strong axial ligand interactions were detected.
• Experimental spectra revealed discrepancies with certain theoretical calculations, highlighting method dependency.

Conclusions:

• The coordination environment of copper in CuOH(+)(H2O)n clusters is more complex than initially assumed.
• The distorted square planar geometry influences the copper center's role in water oxidation catalysis.
• Accurate theoretical modeling of these systems requires careful consideration of the level of theory employed.