Materials Data on NpAsS by Materials Project
NpAsS is Matlockite structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Np5+ is bonded in a 5-coordinate geometry to four equivalent As3- and five equivalent S2- atoms. All Np–As bond lengths are 3.07 Å. There are four shorter (2.79 Å) and one longer (2.80 Å) Np–S bond lengths. As3- is bonded to four equivalent Np5+ and four equivalent As3- atoms to form distorted AsNp4As4 hexagonal bipyramids that share corners with four equivalent AsNp4As4 hexagonal bipyramids, corners with twelve equivalent SNp5 square pyramids, edges with four equivalent AsNp4As4 hexagonal bipyramids, edges with four equivalent SNp5 square pyramids, and faces with four equivalent AsNp4As4 hexagonal bipyramids. All As–As bond lengths are 2.73 Å. S2- is bonded to five equivalent Np5+ atoms to form distorted SNp5 square pyramids that share corners with twelve equivalent AsNp4As4 hexagonal bipyramids, corners with four equivalent SNp5 square pyramids, edges with four equivalent AsNp4As4 hexagonal bipyramids, and edges with eight equivalent SNp5 square pyramids.