Two‐Orbital Three‐Electron Stabilizing Interaction for Direct Co2+As3+ Bonds involving Square‐Planar CoO4 in BaCoAs2O51. (12th February 2014) - David, Rénald
Abstract The quest for new oxides with cations containing active lone‐pair electrons (E) covers a broad field of targeted specificities owing to asymmetric electronic distribution and their particular band structure. Herein, we show that the novel compound BaCoAs2O5, with lone‐pair As3+ ions, is built from rare square‐planar Co2+O4 involved in direct bonding between As3+E and Co2+ dz2 orbitals (CoAs=2.51 Å). By means of DFT and Hückel calculations, we show that this σ‐type overlapping is stabilized by a two‐orbital three‐electron interaction allowed by the high‐spin character of the Co2+ ions. The negligible experimental spin‐orbit coupling is expected from the resulting molecular orbital scheme in O3AsE–CoO4 clusters.