Materials Data on Ca3(SiP2)2 by Materials Project
(Ca)3(SiP2)2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of twelve calcium molecules and two SiP2 ribbons oriented in the (1, 0, 0) direction. In each SiP2 ribbon, there are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 4-coordinate geometry to one Si4- and three P+0.50+ atoms. The Si–Si bond length is 2.34 Å. There are one shorter (2.28 Å) and two longer (2.30 Å) Si–P bond lengths. In the second Si4- site, Si4- is bonded in a 3-coordinate geometry to one Si4- and three P+0.50+ atoms. There are a spread of Si–P bond distances ranging from 2.24–2.32 Å. There are four inequivalent P+0.50+ sites. In the first P+0.50+ site, P+0.50+ is bonded in a single-bond geometry to one Si4- atom. In the second P+0.50+ site, P+0.50+ is bonded in a water-like geometry to two equivalent Si4- atoms. In the third P+0.50+ site, P+0.50+ is bonded in an L-shaped geometry to two Si4- atoms. In the fourth P+0.50+ site, P+0.50+ is bonded in a single-bond geometry to one Si4- atom.