We present first-principle calculations of core-level binding energies for the study of insulating, bulk phase, compounds, based on the Slater-Janak transition state model. Those calculations were performed in order to find a reliable model of the amorphous LixPOyNz solid electrolyte which is able to reproduce its electronic properties gathered from X-ray photoemission spectroscopy (XPS) experiments. As a starting point, Li2PO2N models were investigated. These models, proposed by Du et al. on the basis of thermodynamics and vibrational properties, were the first structural models of LixPOyNz. Thanks to chemical and structural modifications applied to Li2PO2N structures, which allow to demonstrate the relevance of our computational approach, we raise an issue concerning the possibility of encountering a non-bridging kind of nitrogen atoms (=N(-)) in LixPOyNz compounds.

Li x PO y N z is an amorphous solid electrolyte widely used in microbattery devices. The present study, based on a confrontation between experiment and theory, aims at providing new knowledge regarding the ionic conductivity model of such systems in correlation with its structure. The computational strategy involved molecular dynamic simulations and first-principle calculations on molecular and periodic models. The experimental target data involve electronic and vibrational properties and were considered through the simulation of Raman and X-ray photoemission spectra in order to identify characteristic patterns of Li x PO y N z . In particular, the presence of short phosphate chains is suggested by molecular dynamics calculations, and the simulation of Raman spectra clearly evidenced a new coordination for nitrogen atoms in the amorphous state, not considered until now in the experimental structural model of the electrolyte and initially hypothesized based on core level binding energy computations. Monovalent nitrogen atoms together with short phosphate chains were used to build a structural model of the electrolyte and appeared to lead to a better reproduction of the target experimental results, while it implies a necessary refinement of the diffusion schemes commonly considered for lithium ions.

Matrix photolysis of 2-pyrazinyl azides/tetrazolo[1,5-a]pyrazines generates nitrile ylides 15 via pyrazinylnitrenes 13 and triazacycloheptatetraenes 14. The nitrile ylides 15 are characterized by IR spectroscopy in conjunction with harmonic and anharmonic vibrational frequency calculations. The nitrile ylides exist in the matrices in the Z,Z-conformations in which they are born. Substitution on the nitrile carbon of nitrile ylides has a profound effect on their structure. Even different conformers of the same molecule can have differences up to 200 cm(-1) in the IR absorptions of the ylide moieties. Nitrile ylides 15a and 15b (R = H or Cl, R' = H) have allenic structures (15 Allenic). Nitrile ylide 15c (R = R' = CH3) has a distinctly propargylic structure (15 Propargylic) in the experimentally observed Z,Z-conformation.