EuSnAs: the first arsenide adopting the NbCrN structure type

A novel polar intermetallic compound, europium tin arsenide, EuSnAs, was successfully synthesized using a complex multimetal flux reaction. Single-crystal X-ray diffraction reveals that EuSnAs crystallizes in the tetragonal space group P 4/ nmm [ a = 4.35830 (10) and c = 8.9333 (5) Å], adopting the NbCrN structure type. Its layered crystal structure features corrugated Sn sheets separated by [EuAs] slabs. Detailed characterization of the structural relationships between EuSnAs and MoSi 2 -derived structures are also provided. Density functional theory (DFT) calculations indicate metallic behavior with a pronounced pseudogap at the Fermi level. Crystal Orbital Hamilton Population (COHP) and Crystal Orbital Bond Index (COBI) analyses identify Sn—As and Sn—Sn as dominant covalent contacts, as well as somewhat delocalized bonding within the Sn-bearing layers.