YFe6Ga6 crystallizes in the orthorhombic Immm space group. Y(1) is bonded to four equivalent Fe(1), eight equivalent Fe(2), two equivalent Ga(1), two equivalent Ga(2), and four equivalent Ga(3) atoms to form distorted YGa8Fe12 hexagonal bipyramids that share corners with eight equivalent Y(1)Ga8Fe12 hexagonal bipyramids, faces with eight equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, faces with sixteen equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, and faces with two equivalent Y(1)Ga8Fe12 hexagonal bipyramids. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Y(1), four equivalent Fe(2), two equivalent Ga(1), two equivalent Ga(2), and two equivalent Ga(3) atoms to form distorted FeY2Ga6Fe4 cuboctahedra that share corners with six equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, corners with eight equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, edges with three equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, edges with four equivalent Fe(2)Y2Ga6Fe4 cuboctahedra,  a faceface with one Fe(1)Y2Ga6Fe4 cuboctahedra, faces with eight equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, and faces with four equivalent Y(1)Ga8Fe12 hexagonal bipyramids. In the second Fe site, Fe(2) is bonded to two equivalent Y(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ga(1), two equivalent Ga(2), and two equivalent Ga(3) atoms to form distorted FeY2Ga6Fe4 cuboctahedra that share corners with four equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, corners with ten equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, edges with two equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, edges with four equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, faces with four equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, faces with six equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, and faces with four equivalent Y(1)Ga8Fe12 hexagonal bipyramids. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 8-coordinate geometry to one Y(1), two equivalent Fe(1), four equivalent Fe(2), and one Ga(1) atom. In the second Ga site, Ga(2) is bonded in a 10-coordinate geometry to one Y(1), two equivalent Fe(1), four equivalent Fe(2), one Ga(2), and two equivalent Ga(3) atoms. In the third Ga site, Ga(3) is bonded in a 8-coordinate geometry to two equivalent Y(1), two equivalent Fe(1), four equivalent Fe(2), and two equivalent Ga(2) atoms.
YFe6Ga6 crystallizes in the orthorhombic Immm space group. Y(1) is bonded to four equivalent Fe(1), eight equivalent Fe(2), two equivalent Ga(1), two equivalent Ga(2), and four equivalent Ga(3) atoms to form distorted YGa8Fe12 hexagonal bipyramids that share corners with eight equivalent Y(1)Ga8Fe12 hexagonal bipyramids, faces with eight equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, faces with sixteen equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, and faces with two equivalent Y(1)Ga8Fe12 hexagonal bipyramids. All Y(1)-Fe(1) bond lengths are 3.28 Å. All Y(1)-Fe(2) bond lengths are 3.30 Å. Both Y(1)-Ga(1) bond lengths are 2.85 Å. Both Y(1)-Ga(2) bond lengths are 2.99 Å. All Y(1)-Ga(3) bond lengths are 2.98 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent Y(1), four equivalent Fe(2), two equivalent Ga(1), two equivalent Ga(2), and two equivalent Ga(3) atoms to form distorted FeY2Ga6Fe4 cuboctahedra that share corners with six equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, corners with eight equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, edges with three equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, edges with four equivalent Fe(2)Y2Ga6Fe4 cuboctahedra,  a faceface with one Fe(1)Y2Ga6Fe4 cuboctahedra, faces with eight equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, and faces with four equivalent Y(1)Ga8Fe12 hexagonal bipyramids. All Fe(1)-Fe(2) bond lengths are 2.51 Å. Both Fe(1)-Ga(1) bond lengths are 2.64 Å. Both Fe(1)-Ga(2) bond lengths are 2.57 Å. Both Fe(1)-Ga(3) bond lengths are 2.62 Å. In the second Fe site, Fe(2) is bonded to two equivalent Y(1), two equivalent Fe(1), two equivalent Fe(2), two equivalent Ga(1), two equivalent Ga(2), and two equivalent Ga(3) atoms to form distorted FeY2Ga6Fe4 cuboctahedra that share corners with four equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, corners with ten equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, edges with two equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, edges with four equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, faces with four equivalent Fe(1)Y2Ga6Fe4 cuboctahedra, faces with six equivalent Fe(2)Y2Ga6Fe4 cuboctahedra, and faces with four equivalent Y(1)Ga8Fe12 hexagonal bipyramids. Both Fe(2)-Fe(2) bond lengths are 2.53 Å. Both Fe(2)-Ga(1) bond lengths are 2.61 Å. Both Fe(2)-Ga(2) bond lengths are 2.61 Å. Both Fe(2)-Ga(3) bond lengths are 2.55 Å. There are three inequivalent Ga sites. In the first Ga site, Ga(1) is bonded in a 8-coordinate geometry to one Y(1), two equivalent Fe(1), four equivalent Fe(2), and one Ga(1) atom. The Ga(1)-Ga(1) bond length is 2.83 Å. In the second Ga site, Ga(2) is bonded in a 10-coordinate geometry to one Y(1), two equivalent Fe(1), four equivalent Fe(2), one Ga(2), and two equivalent Ga(3) atoms. The Ga(2)-Ga(2) bond length is 2.72 Å. Both Ga(2)-Ga(3) bond lengths are 2.89 Å. In the third Ga site, Ga(3) is bonded in a 8-coordinate geometry to two equivalent Y(1), two equivalent Fe(1), four equivalent Fe(2), and two equivalent Ga(2) atoms.