It's all in the (cyanamide) tilt. Synthesis and structure of NaSc(NCN)${}_2$

The ternary cyanamide NaSc(NCN)${}_2$ was prepared by a solid-state metathesis reaction between Na${}_2$NCN and ScCl${}_3$ at 600 °C. The orthorhombic crystal structure was determined from powder X-ray diffraction data to be isotypic to that of LiY(NCN)${}_2$ with Pbcn symmetry. As such the structure of NaSc(NCN)${}_2$ is well thought of as being derived from [NiAs]-type MNCN binaries with a hexagonally close-packed array of NCN${}^{2-}$. In this hettotypic form, however, the Na${}^{+}$ and Sc${}^{3+}$ cations occupy the octahedral holes in a 1:1 ordered fashion forming corrugated rows within the octahedral planes that alternate along the stacking direction. Furthermore, the significant cation size differential induces a pronounced tilting of the cyanamide anion away from the [100] direction. Electronic structure calculations indicate an indirect band gap of 3.41 eV (SCAN functional), in broad agreement with the measured value of 4.19 eV, which characterizes NaSc(NCN)${}_2$ as a wide-band-gap semiconductor. (© 2020 The Authors. Published by Wiley‐VCH Verlag GmbH and Co. KGaA.)