LaY(MnSi)4 crystallizes in the tetragonal P4/mmm space group. La(1) is bonded in a 8-coordinate geometry to eight equivalent Si(1) atoms. Y(1) is bonded in a 16-coordinate geometry to eight equivalent Mn(1) and eight equivalent Si(2) atoms. Mn(1) is bonded to two equivalent Y(1), two equivalent Si(1), and two equivalent Si(2) atoms to form a mixture of edge, face, and corner-sharing MnY2Si4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent La(1), four equivalent Mn(1), and one Si(1) atom. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Y(1), four equivalent Mn(1), and one Si(2) atom.
LaY(MnSi)4 crystallizes in the tetragonal P4/mmm space group. La(1) is bonded in a 8-coordinate geometry to eight equivalent Si(1) atoms. All La(1)-Si(1) bond lengths are 3.12 Å. Y(1) is bonded in a 16-coordinate geometry to eight equivalent Mn(1) and eight equivalent Si(2) atoms. All Y(1)-Mn(1) bond lengths are 3.26 Å. All Y(1)-Si(2) bond lengths are 3.04 Å. Mn(1) is bonded to two equivalent Y(1), two equivalent Si(1), and two equivalent Si(2) atoms to form a mixture of edge, face, and corner-sharing MnY2Si4 tetrahedra. Both Mn(1)-Si(1) bond lengths are 2.39 Å. Both Mn(1)-Si(2) bond lengths are 2.40 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to four equivalent La(1), four equivalent Mn(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.82 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to four equivalent Y(1), four equivalent Mn(1), and one Si(2) atom. The Si(2)-Si(2) bond length is 2.46 Å.