  A new iron-oxychalcogenide (CaO)(FeSe) was obtained which crystallizes in the
orthorhombic space group Pnma (No. 62) with a = 5.9180(12) {\AA}, b = 3.8802(8)
{\AA}, c = 13.193(3) {\AA}. The unique structure of (CaO)(FeSe) is built up of
a quasi-two-dimensional network of corrugated infinite layers of corner-shared
FeSe2O2 tetrahedra that extend in the ab-plane. The corrugated layers composed
of corner-shared FeSe2O2 tetrahedra stack along the c-axis with Ca2+ cations
sandwiched between the layers. Optical spectroscopy and resistivity
measurements reveal semiconducting behavior with an indirect optical band gap
of around 1.8 eV and an activation energy of 0.19(1) eV. Electronic band
structure calculations at the density function level predict a magnetic
configuration as ground state and confirm the presence of an indirect wide gap
in (CaO)(FeSe).
