Ta3Os2 crystallizes in the orthorhombic Cmm2 space group. There are seven inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 15-coordinate geometry to one Ta(1), one Ta(6), two equivalent Ta(3), two equivalent Ta(5), two equivalent Ta(7), one Os(5), two equivalent Os(2), and four equivalent Os(4) atoms. In the second Ta site, Ta(2) is bonded in a 11-coordinate geometry to one Ta(2), two equivalent Ta(4), two equivalent Os(1), two equivalent Os(5), and four equivalent Os(3) atoms. In the third Ta site, Ta(3) is bonded in a 4-coordinate geometry to one Ta(1), two equivalent Os(3), and two equivalent Os(4) atoms. In the fourth Ta site, Ta(4) is bonded in a 4-coordinate geometry to one Ta(2), two equivalent Os(3), and two equivalent Os(4) atoms. In the fifth Ta site, Ta(5) is bonded in a 7-coordinate geometry to two equivalent Ta(1), two equivalent Ta(7), one Os(2), two equivalent Os(3), and two equivalent Os(4) atoms. In the sixth Ta site, Ta(6) is bonded in a 7-coordinate geometry to one Ta(1), one Os(1), two equivalent Os(3), two equivalent Os(4), and two equivalent Os(5) atoms. In the seventh Ta site, Ta(7) is bonded in a 7-coordinate geometry to two equivalent Ta(1), two equivalent Ta(5), one Os(2), two equivalent Os(3), and two equivalent Os(4) atoms. There are five inequivalent Os sites. In the first Os site, Os(1) is bonded to two equivalent Ta(6), four equivalent Ta(2), two equivalent Os(5), and four equivalent Os(3) atoms to form distorted OsTa6Os6 cuboctahedra that share corners with eight equivalent Os(3)Ta9Os3 cuboctahedra, corners with eight equivalent Os(4)Ta9Os3 cuboctahedra, edges with two equivalent Os(1)Ta6Os6 cuboctahedra, and faces with four equivalent Os(3)Ta9Os3 cuboctahedra. In the second Os site, Os(2) is bonded to two equivalent Ta(5), two equivalent Ta(7), four equivalent Ta(1), and four equivalent Os(4) atoms to form OsTa8Os4 cuboctahedra that share corners with eight equivalent Os(3)Ta9Os3 cuboctahedra, corners with eight equivalent Os(4)Ta9Os3 cuboctahedra, edges with two equivalent Os(2)Ta8Os4 cuboctahedra, and faces with four equivalent Os(4)Ta9Os3 cuboctahedra. In the third Os site, Os(3) is bonded to one Ta(5), one Ta(6), one Ta(7), two equivalent Ta(2), two equivalent Ta(3), two equivalent Ta(4), one Os(1), one Os(3), and one Os(5) atom to form distorted OsTa9Os3 cuboctahedra that share corners with two equivalent Os(1)Ta6Os6 cuboctahedra, corners with two equivalent Os(2)Ta8Os4 cuboctahedra, corners with three equivalent Os(3)Ta9Os3 cuboctahedra, corners with four equivalent Os(4)Ta9Os3 cuboctahedra, edges with three equivalent Os(3)Ta9Os3 cuboctahedra,  a faceface with one Os(1)Ta6Os6 cuboctahedra, faces with two equivalent Os(3)Ta9Os3 cuboctahedra, and faces with four equivalent Os(4)Ta9Os3 cuboctahedra. In the fourth Os site, Os(4) is bonded to one Ta(5), one Ta(6), one Ta(7), two equivalent Ta(1), two equivalent Ta(3), two equivalent Ta(4), one Os(2), one Os(4), and one Os(5) atom to form distorted OsTa9Os3 cuboctahedra that share corners with two equivalent Os(1)Ta6Os6 cuboctahedra, corners with two equivalent Os(2)Ta8Os4 cuboctahedra, corners with three equivalent Os(4)Ta9Os3 cuboctahedra, corners with four equivalent Os(3)Ta9Os3 cuboctahedra, edges with three equivalent Os(4)Ta9Os3 cuboctahedra,  a faceface with one Os(2)Ta8Os4 cuboctahedra, faces with two equivalent Os(4)Ta9Os3 cuboctahedra, and faces with four equivalent Os(3)Ta9Os3 cuboctahedra. In the fifth Os site, Os(5) is bonded in a distorted linear geometry to one Ta(1), two equivalent Ta(2), two equivalent Ta(6), one Os(1), two equivalent Os(3), and two equivalent Os(4) atoms.
Ta3Os2 crystallizes in the orthorhombic Cmm2 space group. There are seven inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 15-coordinate geometry to one Ta(1), one Ta(6), two equivalent Ta(3), two equivalent Ta(5), two equivalent Ta(7), one Os(5), two equivalent Os(2), and four equivalent Os(4) atoms. The Ta(1)-Ta(1) bond length is 2.87 Å. The Ta(1)-Ta(6) bond length is 3.27 Å. Both Ta(1)-Ta(3) bond lengths are 2.72 Å. Both Ta(1)-Ta(5) bond lengths are 3.16 Å. Both Ta(1)-Ta(7) bond lengths are 3.18 Å. The Ta(1)-Os(5) bond length is 3.28 Å. There is one shorter (2.90 Å) and one longer (2.92 Å) Ta(1)-Os(2) bond length. There are two shorter (2.98 Å) and two longer (2.99 Å) Ta(1)-Os(4) bond lengths. In the second Ta site, Ta(2) is bonded in a 11-coordinate geometry to one Ta(2), two equivalent Ta(4), two equivalent Os(1), two equivalent Os(5), and four equivalent Os(3) atoms. The Ta(2)-Ta(2) bond length is 2.82 Å. Both Ta(2)-Ta(4) bond lengths are 2.73 Å. There is one shorter (2.83 Å) and one longer (2.97 Å) Ta(2)-Os(1) bond length. Both Ta(2)-Os(5) bond lengths are 3.18 Å. There are two shorter (2.96 Å) and two longer (3.01 Å) Ta(2)-Os(3) bond lengths. In the third Ta site, Ta(3) is bonded in a 4-coordinate geometry to one Ta(1), two equivalent Os(3), and two equivalent Os(4) atoms. There is one shorter (2.79 Å) and one longer (2.84 Å) Ta(3)-Os(3) bond length. Both Ta(3)-Os(4) bond lengths are 2.78 Å. In the fourth Ta site, Ta(4) is bonded in a 4-coordinate geometry to one Ta(2), two equivalent Os(3), and two equivalent Os(4) atoms. There is one shorter (2.77 Å) and one longer (2.79 Å) Ta(4)-Os(3) bond length. There is one shorter (2.78 Å) and one longer (2.84 Å) Ta(4)-Os(4) bond length. In the fifth Ta site, Ta(5) is bonded in a 7-coordinate geometry to two equivalent Ta(1), two equivalent Ta(7), one Os(2), two equivalent Os(3), and two equivalent Os(4) atoms. Both Ta(5)-Ta(7) bond lengths are 2.53 Å. The Ta(5)-Os(2) bond length is 2.83 Å. Both Ta(5)-Os(3) bond lengths are 2.87 Å. Both Ta(5)-Os(4) bond lengths are 2.89 Å. In the sixth Ta site, Ta(6) is bonded in a 7-coordinate geometry to one Ta(1), one Os(1), two equivalent Os(3), two equivalent Os(4), and two equivalent Os(5) atoms. The Ta(6)-Os(1) bond length is 2.88 Å. Both Ta(6)-Os(3) bond lengths are 2.85 Å. Both Ta(6)-Os(4) bond lengths are 2.83 Å. There is one shorter (2.53 Å) and one longer (2.54 Å) Ta(6)-Os(5) bond length. In the seventh Ta site, Ta(7) is bonded in a 7-coordinate geometry to two equivalent Ta(1), two equivalent Ta(5), one Os(2), two equivalent Os(3), and two equivalent Os(4) atoms. The Ta(7)-Os(2) bond length is 2.83 Å. Both Ta(7)-Os(3) bond lengths are 2.86 Å. Both Ta(7)-Os(4) bond lengths are 2.89 Å. There are five inequivalent Os sites. In the first Os site, Os(1) is bonded to two equivalent Ta(6), four equivalent Ta(2), two equivalent Os(5), and four equivalent Os(3) atoms to form distorted OsTa6Os6 cuboctahedra that share corners with eight equivalent Os(3)Ta9Os3 cuboctahedra, corners with eight equivalent Os(4)Ta9Os3 cuboctahedra, edges with two equivalent Os(1)Ta6Os6 cuboctahedra, and faces with four equivalent Os(3)Ta9Os3 cuboctahedra. Both Os(1)-Os(5) bond lengths are 2.79 Å. All Os(1)-Os(3) bond lengths are 2.62 Å. In the second Os site, Os(2) is bonded to two equivalent Ta(5), two equivalent Ta(7), four equivalent Ta(1), and four equivalent Os(4) atoms to form OsTa8Os4 cuboctahedra that share corners with eight equivalent Os(3)Ta9Os3 cuboctahedra, corners with eight equivalent Os(4)Ta9Os3 cuboctahedra, edges with two equivalent Os(2)Ta8Os4 cuboctahedra, and faces with four equivalent Os(4)Ta9Os3 cuboctahedra. All Os(2)-Os(4) bond lengths are 2.65 Å. In the third Os site, Os(3) is bonded to one Ta(5), one Ta(6), one Ta(7), two equivalent Ta(2), two equivalent Ta(3), two equivalent Ta(4), one Os(1), one Os(3), and one Os(5) atom to form distorted OsTa9Os3 cuboctahedra that share corners with two equivalent Os(1)Ta6Os6 cuboctahedra, corners with two equivalent Os(2)Ta8Os4 cuboctahedra, corners with three equivalent Os(3)Ta9Os3 cuboctahedra, corners with four equivalent Os(4)Ta9Os3 cuboctahedra, edges with three equivalent Os(3)Ta9Os3 cuboctahedra,  a faceface with one Os(1)Ta6Os6 cuboctahedra, faces with two equivalent Os(3)Ta9Os3 cuboctahedra, and faces with four equivalent Os(4)Ta9Os3 cuboctahedra. The Os(3)-Os(3) bond length is 2.68 Å. The Os(3)-Os(5) bond length is 2.85 Å. In the fourth Os site, Os(4) is bonded to one Ta(5), one Ta(6), one Ta(7), two equivalent Ta(1), two equivalent Ta(3), two equivalent Ta(4), one Os(2), one Os(4), and one Os(5) atom to form distorted OsTa9Os3 cuboctahedra that share corners with two equivalent Os(1)Ta6Os6 cuboctahedra, corners with two equivalent Os(2)Ta8Os4 cuboctahedra, corners with three equivalent Os(4)Ta9Os3 cuboctahedra, corners with four equivalent Os(3)Ta9Os3 cuboctahedra, edges with three equivalent Os(4)Ta9Os3 cuboctahedra,  a faceface with one Os(2)Ta8Os4 cuboctahedra, faces with two equivalent Os(4)Ta9Os3 cuboctahedra, and faces with four equivalent Os(3)Ta9Os3 cuboctahedra. The Os(4)-Os(4) bond length is 2.65 Å. The Os(4)-Os(5) bond length is 2.82 Å. In the fifth Os site, Os(5) is bonded in a distorted linear geometry to one Ta(1), two equivalent Ta(2), two equivalent Ta(6), one Os(1), two equivalent Os(3), and two equivalent Os(4) atoms.