DOE OSTI2020
UP2 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. there are three inequivalent U6+ sites. In the first U6+ site, U6+ is bonded in a 9-coordinate geometry to nine P3- atoms. There are a spread of U–P bond distances ranging from 2.76–2.95 Å. In the second U6+ site, U6+ is bonded in a 9-coordinate geometry to nine P3- atoms. There are a spread of U–P bond distances ranging from 2.72–2.86 Å. In the third U6+ site, U6+ is bonded in a 9-coordinate geometry to nine P3- atoms. There are a spread of U–P bond distances ranging from 2.73–2.90 Å. There are four inequivalent P3- sites. In the first P3- site, P3- is bonded to five U6+ atoms to form a mixture of edge and corner-sharing PU5 trigonal bipyramids. In the second P3- site, P3- is bonded to five U6+ atoms to form a mixture of distorted edge and corner-sharing PU5 trigonal bipyramids. In the third P3- site, P3- is bonded to five U6+ atoms to form a mixture of edge and corner-sharing PU5 square pyramids. In the fourth P3- site, P3- is bonded in a 6-coordinate geometry to four U6+ and two equivalent P3- atoms. Both P–P bond lengths are 2.43 Å.