Si is BC8 structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids. In the second Si site, Si(2) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids.
Si is BC8 structured and crystallizes in the trigonal R-3 space group. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids. The Si(1)-Si(2) bond length is 2.38 Å. There is one shorter (2.34 Å) and two longer (2.38 Å) Si(1)-Si(1) bond lengths. In the second Si site, Si(2) is bonded to one Si(2) and three equivalent Si(1) atoms to form corner-sharing SiSi4 trigonal pyramids. The Si(2)-Si(2) bond length is 2.41 Å.