Ta3N5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 8-coordinate geometry to two equivalent N(1), two equivalent N(2), two equivalent N(3), and two equivalent N(4) atoms. In the second Ta site, Ta(2) is bonded in a 7-coordinate geometry to one N(2), one N(3), one N(4), and four equivalent N(1) atoms. There are four inequivalent N sites. In the first N site, N(1) is bonded to two equivalent Ta(1) and two equivalent Ta(2) atoms to form NTa4 tetrahedra that share corners with two equivalent N(2)Ta5 square pyramids, corners with four equivalent N(3)Ta5 square pyramids, corners with six equivalent N(1)Ta4 tetrahedra, corners with two equivalent N(4)Ta5 trigonal bipyramids,  an edgeedge with one N(3)Ta5 square pyramid, edges with two equivalent N(2)Ta5 square pyramids,  an edgeedge with one N(1)Ta4 tetrahedra, and edges with two equivalent N(4)Ta5 trigonal bipyramids. In the second N site, N(2) is bonded to one Ta(2) and four equivalent Ta(1) atoms to form distorted NTa5 square pyramids that share corners with four equivalent N(2)Ta5 square pyramids, corners with four equivalent N(3)Ta5 square pyramids, corners with four equivalent N(1)Ta4 tetrahedra,  a cornercorner with one N(4)Ta5 trigonal bipyramid,  an edgeedge with one N(3)Ta5 square pyramid, edges with four equivalent N(1)Ta4 tetrahedra, edges with four equivalent N(4)Ta5 trigonal bipyramids, and  a faceface with one N(3)Ta5 square pyramid. In the third N site, N(3) is bonded to one Ta(2) and four equivalent Ta(1) atoms to form NTa5 square pyramids that share corners with four equivalent N(2)Ta5 square pyramids, corners with eight equivalent N(1)Ta4 tetrahedra, corners with five equivalent N(4)Ta5 trigonal bipyramids,  an edgeedge with one N(2)Ta5 square pyramid, edges with two equivalent N(3)Ta5 square pyramids, edges with two equivalent N(1)Ta4 tetrahedra, edges with two equivalent N(4)Ta5 trigonal bipyramids, and  a faceface with one N(2)Ta5 square pyramid. In the fourth N site, N(4) is bonded to one Ta(2) and four equivalent Ta(1) atoms to form distorted NTa5 trigonal bipyramids that share  a cornercorner with one N(2)Ta5 square pyramid, corners with five equivalent N(3)Ta5 square pyramids, corners with four equivalent N(1)Ta4 tetrahedra, corners with four equivalent N(4)Ta5 trigonal bipyramids, edges with two equivalent N(3)Ta5 square pyramids, edges with four equivalent N(2)Ta5 square pyramids, and edges with four equivalent N(1)Ta4 tetrahedra.
Ta3N5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 8-coordinate geometry to two equivalent N(1), two equivalent N(2), two equivalent N(3), and two equivalent N(4) atoms. There is one shorter (2.11 Å) and one longer (2.15 Å) Ta(1)-N(1) bond length. There is one shorter (2.21 Å) and one longer (2.24 Å) Ta(1)-N(2) bond length. There is one shorter (2.27 Å) and one longer (2.30 Å) Ta(1)-N(3) bond length. There is one shorter (2.27 Å) and one longer (2.30 Å) Ta(1)-N(4) bond length. In the second Ta site, Ta(2) is bonded in a 7-coordinate geometry to one N(2), one N(3), one N(4), and four equivalent N(1) atoms. The Ta(2)-N(2) bond length is 2.10 Å. The Ta(2)-N(3) bond length is 2.15 Å. The Ta(2)-N(4) bond length is 2.31 Å. There are two shorter (2.02 Å) and two longer (2.13 Å) Ta(2)-N(1) bond lengths. There are four inequivalent N sites. In the first N site, N(1) is bonded to two equivalent Ta(1) and two equivalent Ta(2) atoms to form NTa4 tetrahedra that share corners with two equivalent N(2)Ta5 square pyramids, corners with four equivalent N(3)Ta5 square pyramids, corners with six equivalent N(1)Ta4 tetrahedra, corners with two equivalent N(4)Ta5 trigonal bipyramids,  an edgeedge with one N(3)Ta5 square pyramid, edges with two equivalent N(2)Ta5 square pyramids,  an edgeedge with one N(1)Ta4 tetrahedra, and edges with two equivalent N(4)Ta5 trigonal bipyramids. In the second N site, N(2) is bonded to one Ta(2) and four equivalent Ta(1) atoms to form distorted NTa5 square pyramids that share corners with four equivalent N(2)Ta5 square pyramids, corners with four equivalent N(3)Ta5 square pyramids, corners with four equivalent N(1)Ta4 tetrahedra,  a cornercorner with one N(4)Ta5 trigonal bipyramid,  an edgeedge with one N(3)Ta5 square pyramid, edges with four equivalent N(1)Ta4 tetrahedra, edges with four equivalent N(4)Ta5 trigonal bipyramids, and  a faceface with one N(3)Ta5 square pyramid. In the third N site, N(3) is bonded to one Ta(2) and four equivalent Ta(1) atoms to form NTa5 square pyramids that share corners with four equivalent N(2)Ta5 square pyramids, corners with eight equivalent N(1)Ta4 tetrahedra, corners with five equivalent N(4)Ta5 trigonal bipyramids,  an edgeedge with one N(2)Ta5 square pyramid, edges with two equivalent N(3)Ta5 square pyramids, edges with two equivalent N(1)Ta4 tetrahedra, edges with two equivalent N(4)Ta5 trigonal bipyramids, and  a faceface with one N(2)Ta5 square pyramid. In the fourth N site, N(4) is bonded to one Ta(2) and four equivalent Ta(1) atoms to form distorted NTa5 trigonal bipyramids that share  a cornercorner with one N(2)Ta5 square pyramid, corners with five equivalent N(3)Ta5 square pyramids, corners with four equivalent N(1)Ta4 tetrahedra, corners with four equivalent N(4)Ta5 trigonal bipyramids, edges with two equivalent N(3)Ta5 square pyramids, edges with four equivalent N(2)Ta5 square pyramids, and edges with four equivalent N(1)Ta4 tetrahedra.