Characterization of the BNNO Radical

Abstract

The cyclic, trans, and cis BNNO molecules and the two isomerization reactions on their doublet electronic states potential energy surface (PES) are systematically investigated. Ab initio self-consistent field, complete active space self-consistent field, coupled cluster with single and double excitations (CCSD), and CCSD including perturbative triple excitations [CCSD(T)] quantum mechanical techniques are employed, in conjunction with Dunning's correlation consistent polarized valence basis sets (cc-pVXZ and aug-cc-pVXZ, where X = D, T, and Q). All stationary points located on the doublet PES lie within 19 kcal mol(-1) of the global minimum cyclic isomer at the aug-cc-pVQZ CCSD(T) level of theory. The cyclic and trans minima are separated by 2.4 kcal mol(-1) with an interconversion barrier (cyclic → TS2 → trans) of 18.3 kcal mol(-1); the trans and cis isomers are separated by 10.4 kcal mol(-1) with a barrier (trans → TS1 → cis) of 10.4 kcal mol(-1). The dissociation energies BNNO (X̃ (2)A') → B ((2)Pu) + NNO (X̃ (1)Σ(+)) for the cyclic, trans, and cis isomers are predicted to be 39.7, 37.3, and 27.0 kcal mol(-1), respectively. The diatomic fragment dissociation energies BNNO (X̃ (2)A') → BN (X (3)Π) + NO (X (2)Σ(+)) for the three isomers are determined to be 50.7, 48.4, and 38.0 kcal mol(-1), respectively. Additionally, fundamental vibrational frequencies are computed for the cyclic and trans isomers through application of second-order vibrational perturbation theory (VPT2) at the cc-pCVTZ CCSD(T) level of theory. Comparison of the resulting vibrational frequencies and their isotopic shifts with those determined experimentally by Wang and Zhou yields the surprising result that the B ((2)Pu) + NNO (X̃ (1)Σ(+)) reaction leads to formation of the trans isomer. The latter structure is not the global minimum, rather the second lowest lying isomer. This apparent disparity is rationalized by detailed examination of the PES describing this reaction.

How water flips at charged titanium dioxide: an SFG-study on the water–TiO2 interface

“…For the rutile (110) surface for example, water is believed to adsorb only in an undissociated manner by interacting with the terminal, five-fold coordinated titanium atoms. 12,13 This is also the case for the anatase (101) facet, whereas for the anatase (001) facet, water adsorbs dissociatively. 14 Though these simulations can give deep insights into the water-TiO 2 interface, they rely on the assumption of a perfect single crystalline structure, which is not realistic for commercially applicable devices.…”

Water effect on band alignment of GaP: A theoretical insight into pyridinium catalyzed CO 2 reduction

“…However, we need to point out that in this work we only use a model with adsorption of 1 ML water. To realistically represent hydration effect, we will need to set up a full GaP(110)-water interface model, and use sampling techniques such as molecular dynamics to properly account for the dynamic behavior of solid-aqueous interfaces [26,[39][40][41][42] . This is currently under study, and will be reported in future.…”

Electronic structure of aqueous-phase anatase titanium dioxide nanoparticles probed by liquid jet photoelectron spectroscopy

“…This nding is in agreement with previous theoretical studies on the stability of hydroxylated congurations 59 and on the proton transfer between a TiO 2 surface and hydronium in solution. 61 We would also like to stress that the liquid-jet PE technique is truly complementary to ambient-pressure PE spectroscopy, with the latter ideally suited for investigation of crystalline surfaces covered by several water or aqueous solution monolayers at neutral pH. As shown here, investigation of the respective nanoparticles (TiO 2 ) fully dispersed in an aqueous solution enables unique access to the study of the TiO 2 -water interface as a function of pH.…”

“…We are aware of a single density functional theory (DFT) molecular dynamic work studying the acidity of the surface groups relevant in the water interaction with a rutile (110) surface. 61 It was predicted that the fraction of terminal water molecules (TiOH 2 ) is small at neutral pH, and the surface pK a for this site has been estimated to be 9. In contrast, a pK a value of À1 was estimated for the surface hydroxide bridge groups (Ti 2 OH + ).…”