Materials Data on Ca3(Si4P7)2 by Materials Project

(Ca)3(Si4P7)2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of six calcium molecules and two Si4P7 ribbons oriented in the (1, 0, 0) direction. In each Si4P7 ribbon, there are four inequivalent Si4- sites. In the first Si4- site, Si4- is bonded to one Si4- and three P+1.86+ atoms to form distorted corner-sharing SiSiP3 tetrahedra. The Si–Si bond length is 2.38 Å. There are two shorter (2.24 Å) and one longer (2.25 Å) Si–P bond lengths. In the second Si4- site, Si4- is bonded to one Si4- and three P+1.86+ atoms to form distorted corner-sharing SiSiP3 tetrahedra. There are two shorter (2.26 Å) and one longer (2.27 Å) Si–P bond lengths. In the third Si4- site, Si4- is bonded to four P+1.86+ atoms to form corner-sharing SiP4 tetrahedra. There are a spread of Si–P bond distances ranging from 2.25–2.28 Å. In the fourth Si4- site, Si4- is bonded to four P+1.86+ atoms to form corner-sharing SiP4 tetrahedra. There are a spread of Si–P bond distances ranging from 2.27–2.30 Å. There are seven inequivalent P+1.86+ sites. In the first P+1.86+ site, P+1.86+ is bonded in a single-bond geometry to one Si4- atom. In the second P+1.86+ site, P+1.86+ is bonded in a trigonal non-coplanar geometry to three Si4- atoms. In the third P+1.86+ site, P+1.86+ is bonded in a trigonal non-coplanar geometry to three Si4- atoms. In the fourth P+1.86+ site, P+1.86+ is bonded in a water-like geometry to two equivalent Si4- atoms. In the fifth P+1.86+ site, P+1.86+ is bonded in a water-like geometry to two Si4- atoms. In the sixth P+1.86+ site, P+1.86+ is bonded in a water-like geometry to two Si4- atoms. In the seventh P+1.86+ site, P+1.86+ is bonded in a single-bond geometry to one Si4- atom.