title: Two-orbital three-electron stabilizing interaction for direct Co2+ - As3+ bonds involving square-planar CoO4 in BaCoAs2O5.
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 BaCoAs2 O5, with lone-pair As(3+) ions, is built from rare square-planar Co(2+) O4 involved in direct bonding between As(3+) E and Co(2+) 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 Co(2+) ions. The negligible experimental spin-orbit coupling is expected from the resulting molecular orbital scheme in O3 AsE-CoO4 clusters.
authors: Université Lille Nord de France, CNRS UMR8181, Unité de Catalyse et de Chimie du Solide, UCCS USTL, 59655 Villeneuve d'Ascq (France).
authors: Rénald
authors: R
authors: David
authors: Houria
authors: H
authors: Kabbour
authors: Alain
authors: A
authors: Pautrat
authors: Nadia
authors: N
authors: Touati
authors: Myung-Hwan
authors: MH
authors: Whangbo
authors: Olivier
authors: O
authors: Mentré
keywords: arsenites; cobalt; electronic structure; molecular modeling; solid-state structures