TcAl4 crystallizes in the monoclinic Cm space group. There are two inequivalent Tc sites. In the first Tc site, Tc(1) is bonded in a 10-coordinate geometry to two equivalent Al(1), two equivalent Al(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Al(5) atoms. In the second Tc site, Tc(2) is bonded in a 11-coordinate geometry to one Al(1), one Al(2), one Al(3), two equivalent Al(4), two equivalent Al(5), two equivalent Al(6), and two equivalent Al(7) atoms. There are seven inequivalent Al sites. In the first Al site, Al(1) is bonded in a 11-coordinate geometry to two equivalent Tc(1), two equivalent Tc(2), one Al(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Al(5) atoms. In the second Al site, Al(2) is bonded in a 13-coordinate geometry to two equivalent Tc(1), two equivalent Tc(2), one Al(1), two equivalent Al(4), two equivalent Al(5), and four equivalent Al(3) atoms. In the third Al site, Al(3) is bonded in a distorted linear geometry to one Tc(1), one Tc(2), one Al(1), one Al(6), and two equivalent Al(2) atoms. In the fourth Al site, Al(4) is bonded in a 3-coordinate geometry to one Tc(1), two equivalent Tc(2), one Al(1), one Al(2), one Al(6), and two equivalent Al(7) atoms. In the fifth Al site, Al(5) is bonded in a 3-coordinate geometry to one Tc(1), two equivalent Tc(2), one Al(1), one Al(2), one Al(6), and two equivalent Al(7) atoms. In the sixth Al site, Al(6) is bonded in a 10-coordinate geometry to two equivalent Tc(2), one Al(3), one Al(4), one Al(5), two equivalent Al(6), and three equivalent Al(7) atoms. In the seventh Al site, Al(7) is bonded in a 11-coordinate geometry to two equivalent Tc(2), two equivalent Al(4), two equivalent Al(5), two equivalent Al(7), and three equivalent Al(6) atoms.
TcAl4 crystallizes in the monoclinic Cm space group. There are two inequivalent Tc sites. In the first Tc site, Tc(1) is bonded in a 10-coordinate geometry to two equivalent Al(1), two equivalent Al(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Al(5) atoms. There is one shorter (2.61 Å) and one longer (2.75 Å) Tc(1)-Al(1) bond length. There is one shorter (2.59 Å) and one longer (2.80 Å) Tc(1)-Al(2) bond length. Both Tc(1)-Al(3) bond lengths are 2.50 Å. Both Tc(1)-Al(4) bond lengths are 2.60 Å. Both Tc(1)-Al(5) bond lengths are 2.65 Å. In the second Tc site, Tc(2) is bonded in a 11-coordinate geometry to one Al(1), one Al(2), one Al(3), two equivalent Al(4), two equivalent Al(5), two equivalent Al(6), and two equivalent Al(7) atoms. The Tc(2)-Al(1) bond length is 2.80 Å. The Tc(2)-Al(2) bond length is 2.77 Å. The Tc(2)-Al(3) bond length is 2.47 Å. There is one shorter (2.61 Å) and one longer (2.71 Å) Tc(2)-Al(4) bond length. There is one shorter (2.65 Å) and one longer (2.72 Å) Tc(2)-Al(5) bond length. There is one shorter (2.65 Å) and one longer (2.78 Å) Tc(2)-Al(6) bond length. There is one shorter (2.63 Å) and one longer (2.75 Å) Tc(2)-Al(7) bond length. There are seven inequivalent Al sites. In the first Al site, Al(1) is bonded in a 11-coordinate geometry to two equivalent Tc(1), two equivalent Tc(2), one Al(2), two equivalent Al(3), two equivalent Al(4), and two equivalent Al(5) atoms. The Al(1)-Al(2) bond length is 2.79 Å. Both Al(1)-Al(3) bond lengths are 2.91 Å. Both Al(1)-Al(4) bond lengths are 2.91 Å. Both Al(1)-Al(5) bond lengths are 2.67 Å. In the second Al site, Al(2) is bonded in a 13-coordinate geometry to two equivalent Tc(1), two equivalent Tc(2), one Al(1), two equivalent Al(4), two equivalent Al(5), and four equivalent Al(3) atoms. Both Al(2)-Al(4) bond lengths are 2.67 Å. Both Al(2)-Al(5) bond lengths are 3.10 Å. There are two shorter (2.95 Å) and two longer (3.03 Å) Al(2)-Al(3) bond lengths. In the third Al site, Al(3) is bonded in a distorted linear geometry to one Tc(1), one Tc(2), one Al(1), one Al(6), and two equivalent Al(2) atoms. The Al(3)-Al(6) bond length is 2.79 Å. In the fourth Al site, Al(4) is bonded in a 3-coordinate geometry to one Tc(1), two equivalent Tc(2), one Al(1), one Al(2), one Al(6), and two equivalent Al(7) atoms. The Al(4)-Al(6) bond length is 2.89 Å. There is one shorter (2.71 Å) and one longer (2.77 Å) Al(4)-Al(7) bond length. In the fifth Al site, Al(5) is bonded in a 3-coordinate geometry to one Tc(1), two equivalent Tc(2), one Al(1), one Al(2), one Al(6), and two equivalent Al(7) atoms. The Al(5)-Al(6) bond length is 2.73 Å. There is one shorter (2.75 Å) and one longer (2.95 Å) Al(5)-Al(7) bond length. In the sixth Al site, Al(6) is bonded in a 10-coordinate geometry to two equivalent Tc(2), one Al(3), one Al(4), one Al(5), two equivalent Al(6), and three equivalent Al(7) atoms. Both Al(6)-Al(6) bond lengths are 2.65 Å. There are a spread of Al(6)-Al(7) bond distances ranging from 2.65-2.77 Å. In the seventh Al site, Al(7) is bonded in a 11-coordinate geometry to two equivalent Tc(2), two equivalent Al(4), two equivalent Al(5), two equivalent Al(7), and three equivalent Al(6) atoms. Both Al(7)-Al(7) bond lengths are 2.58 Å.