Er5Pt4 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 6-coordinate geometry to one Pt(3), two equivalent Pt(2), and three equivalent Pt(1) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one Pt(2), two equivalent Pt(3), and four equivalent Pt(1) atoms. In the third Er site, Er(3) is bonded to two equivalent Pt(1), two equivalent Pt(2), and two equivalent Pt(3) atoms to form distorted corner-sharing ErPt6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. There are three inequivalent Pt sites. In the first Pt site, Pt(3) is bonded in a 9-coordinate geometry to two equivalent Er(1), two equivalent Er(3), four equivalent Er(2), and one Pt(2) atom. In the second Pt site, Pt(1) is bonded in a 8-coordinate geometry to one Er(3), three equivalent Er(1), and four equivalent Er(2) atoms. In the third Pt site, Pt(2) is bonded in a 9-coordinate geometry to two equivalent Er(2), two equivalent Er(3), four equivalent Er(1), and one Pt(3) atom.
Er5Pt4 crystallizes in the orthorhombic Pnma space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 6-coordinate geometry to one Pt(3), two equivalent Pt(2), and three equivalent Pt(1) atoms. The Er(1)-Pt(3) bond length is 2.97 Å. There is one shorter (2.89 Å) and one longer (2.90 Å) Er(1)-Pt(2) bond length. There are two shorter (2.80 Å) and one longer (2.95 Å) Er(1)-Pt(1) bond length. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one Pt(2), two equivalent Pt(3), and four equivalent Pt(1) atoms. The Er(2)-Pt(2) bond length is 3.16 Å. There is one shorter (2.93 Å) and one longer (3.29 Å) Er(2)-Pt(3) bond length. There are a spread of Er(2)-Pt(1) bond distances ranging from 2.93-3.21 Å. In the third Er site, Er(3) is bonded to two equivalent Pt(1), two equivalent Pt(2), and two equivalent Pt(3) atoms to form distorted corner-sharing ErPt6 octahedra. The corner-sharing octahedral tilt angles range from 48-53°. Both Er(3)-Pt(1) bond lengths are 3.03 Å. There is one shorter (2.86 Å) and one longer (3.16 Å) Er(3)-Pt(2) bond length. There is one shorter (2.78 Å) and one longer (2.86 Å) Er(3)-Pt(3) bond length. There are three inequivalent Pt sites. In the first Pt site, Pt(3) is bonded in a 9-coordinate geometry to two equivalent Er(1), two equivalent Er(3), four equivalent Er(2), and one Pt(2) atom. The Pt(3)-Pt(2) bond length is 2.77 Å. In the second Pt site, Pt(1) is bonded in a 8-coordinate geometry to one Er(3), three equivalent Er(1), and four equivalent Er(2) atoms. In the third Pt site, Pt(2) is bonded in a 9-coordinate geometry to two equivalent Er(2), two equivalent Er(3), four equivalent Er(1), and one Pt(3) atom.