NpPm3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Np(1) is bonded to twelve equivalent Pm(1) atoms to form NpPm12 cuboctahedra that share corners with six equivalent Np(1)Pm12 cuboctahedra, corners with twelve equivalent Pm(1)Pm8Np4 cuboctahedra, edges with eighteen equivalent Pm(1)Pm8Np4 cuboctahedra, faces with eight equivalent Np(1)Pm12 cuboctahedra, and faces with twelve equivalent Pm(1)Pm8Np4 cuboctahedra. Pm(1) is bonded to four equivalent Np(1) and eight equivalent Pm(1) atoms to form PmPm8Np4 cuboctahedra that share corners with four equivalent Np(1)Pm12 cuboctahedra, corners with fourteen equivalent Pm(1)Pm8Np4 cuboctahedra, edges with six equivalent Np(1)Pm12 cuboctahedra, edges with twelve equivalent Pm(1)Pm8Np4 cuboctahedra, faces with four equivalent Np(1)Pm12 cuboctahedra, and faces with sixteen equivalent Pm(1)Pm8Np4 cuboctahedra.
NpPm3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Np(1) is bonded to twelve equivalent Pm(1) atoms to form NpPm12 cuboctahedra that share corners with six equivalent Np(1)Pm12 cuboctahedra, corners with twelve equivalent Pm(1)Pm8Np4 cuboctahedra, edges with eighteen equivalent Pm(1)Pm8Np4 cuboctahedra, faces with eight equivalent Np(1)Pm12 cuboctahedra, and faces with twelve equivalent Pm(1)Pm8Np4 cuboctahedra. There are six shorter (3.52 Å) and six longer (3.58 Å) Np(1)-Pm(1) bond lengths. Pm(1) is bonded to four equivalent Np(1) and eight equivalent Pm(1) atoms to form PmPm8Np4 cuboctahedra that share corners with four equivalent Np(1)Pm12 cuboctahedra, corners with fourteen equivalent Pm(1)Pm8Np4 cuboctahedra, edges with six equivalent Np(1)Pm12 cuboctahedra, edges with twelve equivalent Pm(1)Pm8Np4 cuboctahedra, faces with four equivalent Np(1)Pm12 cuboctahedra, and faces with sixteen equivalent Pm(1)Pm8Np4 cuboctahedra. There are a spread of Pm(1)-Pm(1) bond distances ranging from 3.53-3.64 Å.