TmMn6Sn4Ga2 crystallizes in the hexagonal P6/mmm space group. Tm(1) is bonded to six equivalent Ga(1) and two equivalent Sn(1) atoms to form distorted edge-sharing TmGa6Sn2 hexagonal bipyramids. Mn(1) is bonded in a 6-coordinate geometry to two equivalent Ga(1), two equivalent Sn(1), and two equivalent Sn(2) atoms. Ga(1) is bonded in a 9-coordinate geometry to three equivalent Tm(1) and six equivalent Mn(1) atoms. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 8-coordinate geometry to one Tm(1), six equivalent Mn(1), and one Sn(1) atom. In the second Sn site, Sn(2) is bonded in a 6-coordinate geometry to six equivalent Mn(1) atoms.
TmMn6Sn4Ga2 crystallizes in the hexagonal P6/mmm space group. Tm(1) is bonded to six equivalent Ga(1) and two equivalent Sn(1) atoms to form distorted edge-sharing TmGa6Sn2 hexagonal bipyramids. All Tm(1)-Ga(1) bond lengths are 3.09 Å. Both Tm(1)-Sn(1) bond lengths are 2.91 Å. Mn(1) is bonded in a 6-coordinate geometry to two equivalent Ga(1), two equivalent Sn(1), and two equivalent Sn(2) atoms. Both Mn(1)-Ga(1) bond lengths are 2.58 Å. Both Mn(1)-Sn(1) bond lengths are 2.81 Å. Both Mn(1)-Sn(2) bond lengths are 2.79 Å. Ga(1) is bonded in a 9-coordinate geometry to three equivalent Tm(1) and six equivalent Mn(1) atoms. There are two inequivalent Sn sites. In the first Sn site, Sn(1) is bonded in a 8-coordinate geometry to one Tm(1), six equivalent Mn(1), and one Sn(1) atom. The Sn(1)-Sn(1) bond length is 2.96 Å. In the second Sn site, Sn(2) is bonded in a 6-coordinate geometry to six equivalent Mn(1) atoms.