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SiSe2 is Silicon Disuphide-like structured and crystallizes in the orthorhombic Ibam space group. The structure is one-dimensional and consists of two SiSe2 ribbons oriented in the (1, 0, 0) direction. Si4+ is bonded to four equivalent Se2- atoms to form edge-sharing SiSe4 tetrahedra. All Si–Se bond lengths are 2.30 Å. Se2- is bonded in a distorted L-shaped geometry to two equivalent Si4+ atoms.
SiSe2 is Silicon Disuphide structured and crystallizes in the orthorhombic Ibam space group. The structure is one-dimensional and consists of two SiSe2 ribbons oriented in the (1, 0, 0) direction. Si4+ is bonded to four equivalent Se2- atoms to form edge-sharing SiSe4 tetrahedra. All Si–Se bond lengths are 2.30 Å. Se2- is bonded in an L-shaped geometry to two equivalent Si4+ atoms.
SiSe2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Ibam space group. The structure is zero-dimensional and consists of four $l^{1}-selanyl(selanylidene)silicon molecules. Si4+ is bonded in a linear geometry to two equivalent Se2- atoms. Both Si–Se bond lengths are 2.09 Å. Se2- is bonded in a single-bond geometry to one Si4+ atom.
Co(SiSe2)2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Co2+ is bonded to six Se+0.50- atoms to form CoSe6 octahedra that share corners with twelve equivalent SiSe6 octahedra, edges with two equivalent CoSe6 octahedra, and faces with two equivalent SiSe6 octahedra. The corner-sharing octahedra tilt angles range from 44–53°. There are four shorter (2.45 Å) and two longer (2.46 Å) Co–Se bond lengths. Si is bonded to six Se+0.50- atoms to form SiSe6 octahedra that share corners with six equivalent CoSe6 octahedra, edges with six equivalent SiSe6 octahedra, and a faceface with one CoSe6 octahedra. The corner-sharing octahedra tilt angles range from 44–53°. There are a spread of Si–Se bond distances ranging from 2.52–2.72 Å. There are two inequivalent Se+0.50- sites. In the first Se+0.50- site, Se+0.50- is bonded in a rectangular see-saw-like geometry to one Co2+ and three equivalent Si atoms. In the second Se+0.50- site, Se+0.50- is bonded in a 5-coordinate geometry to two equivalent Co2+ and three equivalent Si atoms.