CaMnSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Ca(1) is bonded to six equivalent Se(1) atoms to form CaSe6 octahedra that share corners with six equivalent Mn(1)Se6 octahedra, edges with six equivalent Ca(1)Se6 octahedra, and edges with six equivalent Mn(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 5°. Mn(1) is bonded to six equivalent Se(1) atoms to form MnSe6 octahedra that share corners with six equivalent Ca(1)Se6 octahedra, edges with six equivalent Ca(1)Se6 octahedra, and edges with six equivalent Mn(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 5°. Se(1) is bonded to three equivalent Ca(1) and three equivalent Mn(1) atoms to form a mixture of corner and edge-sharing SeCa3Mn3 octahedra. The corner-sharing octahedra are not tilted.
CaMnSe2 is Caswellsilverite structured and crystallizes in the trigonal R-3m space group. Ca(1) is bonded to six equivalent Se(1) atoms to form CaSe6 octahedra that share corners with six equivalent Mn(1)Se6 octahedra, edges with six equivalent Ca(1)Se6 octahedra, and edges with six equivalent Mn(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 5°. All Ca(1)-Se(1) bond lengths are 2.94 Å. Mn(1) is bonded to six equivalent Se(1) atoms to form MnSe6 octahedra that share corners with six equivalent Ca(1)Se6 octahedra, edges with six equivalent Ca(1)Se6 octahedra, and edges with six equivalent Mn(1)Se6 octahedra. The corner-sharing octahedral tilt angles are 5°. All Mn(1)-Se(1) bond lengths are 2.76 Å. Se(1) is bonded to three equivalent Ca(1) and three equivalent Mn(1) atoms to form a mixture of corner and edge-sharing SeCa3Mn3 octahedra. The corner-sharing octahedra are not tilted.