TaNi15Al4 is Uranium Silicide-derived structured and crystallizes in the tetragonal P4/mmm space group. Ta(1) is bonded to four equivalent Ni(1) and eight equivalent Ni(4) atoms to form TaNi12 cuboctahedra that share corners with four equivalent Ta(1)Ni12 cuboctahedra, corners with eight equivalent Al(1)Ni12 cuboctahedra, edges with eight equivalent Ni(2)Al4Ni8 cuboctahedra, edges with sixteen equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, faces with two equivalent Al(1)Ni12 cuboctahedra, faces with four equivalent Ta(1)Ni12 cuboctahedra, faces with four equivalent Ni(1)Ta4Ni8 cuboctahedra, and faces with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent Ta(1) and eight equivalent Ni(4) atoms to form distorted NiTa4Ni8 cuboctahedra that share corners with four equivalent Ni(1)Ta4Ni8 cuboctahedra, corners with eight equivalent Ni(2)Al4Ni8 cuboctahedra, edges with eight equivalent Al(1)Ni12 cuboctahedra, edges with sixteen equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, faces with two equivalent Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ta(1)Ni12 cuboctahedra, faces with four equivalent Ni(1)Ta4Ni8 cuboctahedra, and faces with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra. In the second Ni site, Ni(2) is bonded to four equivalent Ni(4), four equivalent Ni(5), and four equivalent Al(1) atoms to form NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(2)Al4Ni8 cuboctahedra, corners with four equivalent Ni(3)Al4Ni8 cuboctahedra, corners with four equivalent Ni(1)Ta4Ni8 cuboctahedra, edges with four equivalent Ta(1)Ni12 cuboctahedra, edges with four equivalent Al(2)Ni12 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra,  a faceface with one Ni(3)Al4Ni8 cuboctahedra,  a faceface with one Ni(1)Ta4Ni8 cuboctahedra, faces with four equivalent Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, and faces with four equivalent Al(1)Ni12 cuboctahedra. In the third Ni site, Ni(3) is bonded to four equivalent Ni(5), four equivalent Ni(6), and four equivalent Al(2) atoms to form NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(2)Al4Ni8 cuboctahedra, corners with eight equivalent Ni(3)Al4Ni8 cuboctahedra, edges with four equivalent Al(1)Ni12 cuboctahedra, edges with four equivalent Al(2)Ni12 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(6)Al4Ni8 cuboctahedra,  a faceface with one Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(6)Al4Ni8 cuboctahedra, faces with four equivalent Al(2)Ni12 cuboctahedra, and faces with five equivalent Ni(3)Al4Ni8 cuboctahedra. In the fourth Ni site, Ni(4) is bonded to two equivalent Ta(1), two equivalent Ni(1), two equivalent Ni(2), four equivalent Ni(4), and two equivalent Al(1) atoms to form distorted NiTa2Al2Ni8 cuboctahedra that share corners with four equivalent Ni(5)Al4Ni8 cuboctahedra, corners with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Ta(1)Ni12 cuboctahedra, edges with four equivalent Ni(2)Al4Ni8 cuboctahedra, edges with four equivalent Ni(5)Al4Ni8 cuboctahedra, edges with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Ni(1)Ta4Ni8 cuboctahedra, edges with four equivalent Al(1)Ni12 cuboctahedra,  a faceface with one Ni(5)Al4Ni8 cuboctahedra, faces with two equivalent Ta(1)Ni12 cuboctahedra, faces with two equivalent Ni(2)Al4Ni8 cuboctahedra, faces with two equivalent Ni(1)Ta4Ni8 cuboctahedra, faces with two equivalent Al(1)Ni12 cuboctahedra, and faces with nine equivalent Ni(4)Ta2Al2Ni8 cuboctahedra. In the fifth Ni site, Ni(5) is bonded to two equivalent Ni(2), two equivalent Ni(3), four equivalent Ni(5), two equivalent Al(1), and two equivalent Al(2) atoms to form distorted NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(5)Al4Ni8 cuboctahedra, corners with four equivalent Ni(6)Al4Ni8 cuboctahedra, corners with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Ni(2)Al4Ni8 cuboctahedra, edges with four equivalent Ni(3)Al4Ni8 cuboctahedra, edges with four equivalent Ni(6)Al4Ni8 cuboctahedra, edges with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Al(1)Ni12 cuboctahedra, edges with four equivalent Al(2)Ni12 cuboctahedra,  a faceface with one Ni(6)Al4Ni8 cuboctahedra,  a faceface with one Ni(4)Ta2Al2Ni8 cuboctahedra, faces with two equivalent Ni(2)Al4Ni8 cuboctahedra, faces with two equivalent Ni(3)Al4Ni8 cuboctahedra, faces with two equivalent Al(1)Ni12 cuboctahedra, faces with two equivalent Al(2)Ni12 cuboctahedra, and faces with eight equivalent Ni(5)Al4Ni8 cuboctahedra. In the sixth Ni site, Ni(6) is bonded to four equivalent Ni(3), four equivalent Ni(6), and four equivalent Al(2) atoms to form NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(6)Al4Ni8 cuboctahedra, corners with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(3)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Al(2)Ni12 cuboctahedra, faces with two equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(3)Al4Ni8 cuboctahedra, faces with four equivalent Al(2)Ni12 cuboctahedra, and faces with eight equivalent Ni(6)Al4Ni8 cuboctahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Ni(2), four equivalent Ni(4), and four equivalent Ni(5) atoms to form AlNi12 cuboctahedra that share corners with four equivalent Ta(1)Ni12 cuboctahedra, corners with four equivalent Al(1)Ni12 cuboctahedra, corners with four equivalent Al(2)Ni12 cuboctahedra, edges with four equivalent Ni(3)Al4Ni8 cuboctahedra, edges with four equivalent Ni(1)Ta4Ni8 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra,  a faceface with one Ta(1)Ni12 cuboctahedra,  a faceface with one Al(2)Ni12 cuboctahedra, faces with four equivalent Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, and faces with four equivalent Al(1)Ni12 cuboctahedra. In the second Al site, Al(2) is bonded to four equivalent Ni(3), four equivalent Ni(5), and four equivalent Ni(6) atoms to form AlNi12 cuboctahedra that share corners with four equivalent Al(1)Ni12 cuboctahedra, corners with eight equivalent Al(2)Ni12 cuboctahedra, edges with four equivalent Ni(2)Al4Ni8 cuboctahedra, edges with four equivalent Ni(3)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(6)Al4Ni8 cuboctahedra,  a faceface with one Al(1)Ni12 cuboctahedra, faces with four equivalent Ni(3)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(6)Al4Ni8 cuboctahedra, and faces with five equivalent Al(2)Ni12 cuboctahedra.
TaNi15Al4 is Uranium Silicide-derived structured and crystallizes in the tetragonal P4/mmm space group. Ta(1) is bonded to four equivalent Ni(1) and eight equivalent Ni(4) atoms to form TaNi12 cuboctahedra that share corners with four equivalent Ta(1)Ni12 cuboctahedra, corners with eight equivalent Al(1)Ni12 cuboctahedra, edges with eight equivalent Ni(2)Al4Ni8 cuboctahedra, edges with sixteen equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, faces with two equivalent Al(1)Ni12 cuboctahedra, faces with four equivalent Ta(1)Ni12 cuboctahedra, faces with four equivalent Ni(1)Ta4Ni8 cuboctahedra, and faces with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra. All Ta(1)-Ni(1) bond lengths are 2.53 Å. All Ta(1)-Ni(4) bond lengths are 2.56 Å. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to four equivalent Ta(1) and eight equivalent Ni(4) atoms to form distorted NiTa4Ni8 cuboctahedra that share corners with four equivalent Ni(1)Ta4Ni8 cuboctahedra, corners with eight equivalent Ni(2)Al4Ni8 cuboctahedra, edges with eight equivalent Al(1)Ni12 cuboctahedra, edges with sixteen equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, faces with two equivalent Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ta(1)Ni12 cuboctahedra, faces with four equivalent Ni(1)Ta4Ni8 cuboctahedra, and faces with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra. All Ni(1)-Ni(4) bond lengths are 2.56 Å. In the second Ni site, Ni(2) is bonded to four equivalent Ni(4), four equivalent Ni(5), and four equivalent Al(1) atoms to form NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(2)Al4Ni8 cuboctahedra, corners with four equivalent Ni(3)Al4Ni8 cuboctahedra, corners with four equivalent Ni(1)Ta4Ni8 cuboctahedra, edges with four equivalent Ta(1)Ni12 cuboctahedra, edges with four equivalent Al(2)Ni12 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra,  a faceface with one Ni(3)Al4Ni8 cuboctahedra,  a faceface with one Ni(1)Ta4Ni8 cuboctahedra, faces with four equivalent Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, and faces with four equivalent Al(1)Ni12 cuboctahedra. All Ni(2)-Ni(4) bond lengths are 2.51 Å. All Ni(2)-Ni(5) bond lengths are 2.51 Å. All Ni(2)-Al(1) bond lengths are 2.53 Å. In the third Ni site, Ni(3) is bonded to four equivalent Ni(5), four equivalent Ni(6), and four equivalent Al(2) atoms to form NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(2)Al4Ni8 cuboctahedra, corners with eight equivalent Ni(3)Al4Ni8 cuboctahedra, edges with four equivalent Al(1)Ni12 cuboctahedra, edges with four equivalent Al(2)Ni12 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(6)Al4Ni8 cuboctahedra,  a faceface with one Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(6)Al4Ni8 cuboctahedra, faces with four equivalent Al(2)Ni12 cuboctahedra, and faces with five equivalent Ni(3)Al4Ni8 cuboctahedra. All Ni(3)-Ni(5) bond lengths are 2.50 Å. All Ni(3)-Ni(6) bond lengths are 2.51 Å. All Ni(3)-Al(2) bond lengths are 2.53 Å. In the fourth Ni site, Ni(4) is bonded to two equivalent Ta(1), two equivalent Ni(1), two equivalent Ni(2), four equivalent Ni(4), and two equivalent Al(1) atoms to form distorted NiTa2Al2Ni8 cuboctahedra that share corners with four equivalent Ni(5)Al4Ni8 cuboctahedra, corners with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Ta(1)Ni12 cuboctahedra, edges with four equivalent Ni(2)Al4Ni8 cuboctahedra, edges with four equivalent Ni(5)Al4Ni8 cuboctahedra, edges with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Ni(1)Ta4Ni8 cuboctahedra, edges with four equivalent Al(1)Ni12 cuboctahedra,  a faceface with one Ni(5)Al4Ni8 cuboctahedra, faces with two equivalent Ta(1)Ni12 cuboctahedra, faces with two equivalent Ni(2)Al4Ni8 cuboctahedra, faces with two equivalent Ni(1)Ta4Ni8 cuboctahedra, faces with two equivalent Al(1)Ni12 cuboctahedra, and faces with nine equivalent Ni(4)Ta2Al2Ni8 cuboctahedra. All Ni(4)-Ni(4) bond lengths are 2.53 Å. Both Ni(4)-Al(1) bond lengths are 2.54 Å. In the fifth Ni site, Ni(5) is bonded to two equivalent Ni(2), two equivalent Ni(3), four equivalent Ni(5), two equivalent Al(1), and two equivalent Al(2) atoms to form distorted NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(5)Al4Ni8 cuboctahedra, corners with four equivalent Ni(6)Al4Ni8 cuboctahedra, corners with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Ni(2)Al4Ni8 cuboctahedra, edges with four equivalent Ni(3)Al4Ni8 cuboctahedra, edges with four equivalent Ni(6)Al4Ni8 cuboctahedra, edges with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, edges with four equivalent Al(1)Ni12 cuboctahedra, edges with four equivalent Al(2)Ni12 cuboctahedra,  a faceface with one Ni(6)Al4Ni8 cuboctahedra,  a faceface with one Ni(4)Ta2Al2Ni8 cuboctahedra, faces with two equivalent Ni(2)Al4Ni8 cuboctahedra, faces with two equivalent Ni(3)Al4Ni8 cuboctahedra, faces with two equivalent Al(1)Ni12 cuboctahedra, faces with two equivalent Al(2)Ni12 cuboctahedra, and faces with eight equivalent Ni(5)Al4Ni8 cuboctahedra. All Ni(5)-Ni(5) bond lengths are 2.53 Å. Both Ni(5)-Al(1) bond lengths are 2.49 Å. Both Ni(5)-Al(2) bond lengths are 2.51 Å. In the sixth Ni site, Ni(6) is bonded to four equivalent Ni(3), four equivalent Ni(6), and four equivalent Al(2) atoms to form NiAl4Ni8 cuboctahedra that share corners with four equivalent Ni(6)Al4Ni8 cuboctahedra, corners with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(3)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Al(2)Ni12 cuboctahedra, faces with two equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(3)Al4Ni8 cuboctahedra, faces with four equivalent Al(2)Ni12 cuboctahedra, and faces with eight equivalent Ni(6)Al4Ni8 cuboctahedra. All Ni(6)-Ni(6) bond lengths are 2.53 Å. All Ni(6)-Al(2) bond lengths are 2.51 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to four equivalent Ni(2), four equivalent Ni(4), and four equivalent Ni(5) atoms to form AlNi12 cuboctahedra that share corners with four equivalent Ta(1)Ni12 cuboctahedra, corners with four equivalent Al(1)Ni12 cuboctahedra, corners with four equivalent Al(2)Ni12 cuboctahedra, edges with four equivalent Ni(3)Al4Ni8 cuboctahedra, edges with four equivalent Ni(1)Ta4Ni8 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(4)Ta2Al2Ni8 cuboctahedra,  a faceface with one Ta(1)Ni12 cuboctahedra,  a faceface with one Al(2)Ni12 cuboctahedra, faces with four equivalent Ni(2)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(4)Ta2Al2Ni8 cuboctahedra, and faces with four equivalent Al(1)Ni12 cuboctahedra. In the second Al site, Al(2) is bonded to four equivalent Ni(3), four equivalent Ni(5), and four equivalent Ni(6) atoms to form AlNi12 cuboctahedra that share corners with four equivalent Al(1)Ni12 cuboctahedra, corners with eight equivalent Al(2)Ni12 cuboctahedra, edges with four equivalent Ni(2)Al4Ni8 cuboctahedra, edges with four equivalent Ni(3)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(5)Al4Ni8 cuboctahedra, edges with eight equivalent Ni(6)Al4Ni8 cuboctahedra,  a faceface with one Al(1)Ni12 cuboctahedra, faces with four equivalent Ni(3)Al4Ni8 cuboctahedra, faces with four equivalent Ni(5)Al4Ni8 cuboctahedra, faces with four equivalent Ni(6)Al4Ni8 cuboctahedra, and faces with five equivalent Al(2)Ni12 cuboctahedra.