U3Pa is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to four equivalent U(1), four equivalent U(2), and four equivalent Pa(1) atoms to form distorted UU8Pa4 cuboctahedra that share corners with twelve equivalent U(1)U8Pa4 cuboctahedra, edges with eight equivalent U(1)U8Pa4 cuboctahedra, edges with eight equivalent Pa(1)U12 cuboctahedra, faces with four equivalent Pa(1)U12 cuboctahedra, and faces with ten equivalent U(1)U8Pa4 cuboctahedra. In the second U site, U(2) is bonded in a square co-planar geometry to eight equivalent U(1) and four equivalent Pa(1) atoms. Pa(1) is bonded to four equivalent U(2) and eight equivalent U(1) atoms to form distorted PaU12 cuboctahedra that share corners with four equivalent Pa(1)U12 cuboctahedra, edges with eight equivalent Pa(1)U12 cuboctahedra, edges with sixteen equivalent U(1)U8Pa4 cuboctahedra, faces with four equivalent Pa(1)U12 cuboctahedra, and faces with eight equivalent U(1)U8Pa4 cuboctahedra.
U3Pa is Uranium Silicide-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to four equivalent U(1), four equivalent U(2), and four equivalent Pa(1) atoms to form distorted UU8Pa4 cuboctahedra that share corners with twelve equivalent U(1)U8Pa4 cuboctahedra, edges with eight equivalent U(1)U8Pa4 cuboctahedra, edges with eight equivalent Pa(1)U12 cuboctahedra, faces with four equivalent Pa(1)U12 cuboctahedra, and faces with ten equivalent U(1)U8Pa4 cuboctahedra. All U(1)-U(1) bond lengths are 2.85 Å. All U(1)-U(2) bond lengths are 3.32 Å. All U(1)-Pa(1) bond lengths are 3.32 Å. In the second U site, U(2) is bonded in a square co-planar geometry to eight equivalent U(1) and four equivalent Pa(1) atoms. All U(2)-Pa(1) bond lengths are 2.85 Å. Pa(1) is bonded to four equivalent U(2) and eight equivalent U(1) atoms to form distorted PaU12 cuboctahedra that share corners with four equivalent Pa(1)U12 cuboctahedra, edges with eight equivalent Pa(1)U12 cuboctahedra, edges with sixteen equivalent U(1)U8Pa4 cuboctahedra, faces with four equivalent Pa(1)U12 cuboctahedra, and faces with eight equivalent U(1)U8Pa4 cuboctahedra.