ELECTRONIC STRUCTURE AND VIBRATIONAL SIGNATURES OF THE DELOCALIZED RADICAL IN HYDRATED CLUSTERS OF COPPER (ÏI") HYDROXIDE, CUOH+(H2O)0-2

Structural, Thermodynamic, and Spectroscopic Evolution in the Hydration of Copper(II) Ions, Cu2+(H2O)2−8

“…21−29 Among these studies, we recently reported two investigations of the electronic structure and radical location of copper(II) hydroxide hydrates, . 30,31 In these studies, the CuOH + ion was shown to exhibit multireference behavior and thereby exist between the two Cu 2+ •••OH − and Cu 1+ •••OH • limiting configurations, which was found to be consistent with recently measured vibrational spectra. 28,32,33 The contribution of each configuration was highly dependent on the degree of hydration, with increased hydration favoring the ionic form, but the radical delocalization nonetheless persisted.…”

“…This cluster size's behavior in isolation could perhaps be explained by the partial charges in Figure 9, where the higher copper charge in 5A leads to a more favorable axial binding site. This trend is belied by the behavior of the larger clusters, however, where the favorability of the The persistent delocalization of the radical was a key discovery in our previous studies of hydrated CuOH + , 30,31 and this behavior is reproduced in the spin densities in the bottom row of 4 carry some spin population, which indicates partial oxidation of the water network as the metal partial charge converges toward approximately +1.6. Whether this partial oxidation is responsible for the success of copper-based water-splitting catalysts remains to be investigated.…”

“…The results of this analysis can be found in Tables S1 and S2 . 30,31 Harmonic zero-point energy (ZPE) corrections were computed with MPW1K/cc-pVTZ frequencies. Our previous analysis of CuOH + hydrates confirmed that results from this mixed basis set agreed well with results from full cc-pVTZ calculations.…”