KEuPS4 crystallizes in the orthorhombic Pnma space group. K(1) is bonded in a 8-coordinate geometry to one S(3), three equivalent S(1), and four equivalent S(2) atoms. Eu(1) is bonded in a 8-coordinate geometry to one S(1), three equivalent S(3), and four equivalent S(2) atoms. P(1) is bonded in a tetrahedral geometry to one S(1), one S(3), and two equivalent S(2) atoms. There are three inequivalent S sites. In the first S site, S(1) is bonded to three equivalent K(1), one Eu(1), and one P(1) atom to form distorted SK3EuP trigonal bipyramids that share corners with six equivalent S(2)K2Eu2P square pyramids, corners with six equivalent S(1)K3EuP trigonal bipyramids, and edges with six equivalent S(2)K2Eu2P square pyramids. In the second S site, S(2) is bonded to two equivalent K(1), two equivalent Eu(1), and one P(1) atom to form distorted SK2Eu2P square pyramids that share corners with six equivalent S(2)K2Eu2P square pyramids, corners with three equivalent S(1)K3EuP trigonal bipyramids, edges with two equivalent S(2)K2Eu2P square pyramids, edges with three equivalent S(1)K3EuP trigonal bipyramids, and  a faceface with one S(2)K2Eu2P square pyramid. In the third S site, S(3) is bonded in a 5-coordinate geometry to one K(1), three equivalent Eu(1), and one P(1) atom.
KEuPS4 crystallizes in the orthorhombic Pnma space group. K(1) is bonded in a 8-coordinate geometry to one S(3), three equivalent S(1), and four equivalent S(2) atoms. The K(1)-S(3) bond length is 3.40 Å. There are two shorter (3.42 Å) and one longer (3.56 Å) K(1)-S(1) bond length. There are two shorter (3.35 Å) and two longer (3.37 Å) K(1)-S(2) bond lengths. Eu(1) is bonded in a 8-coordinate geometry to one S(1), three equivalent S(3), and four equivalent S(2) atoms. The Eu(1)-S(1) bond length is 2.98 Å. There is one shorter (3.02 Å) and two longer (3.44 Å) Eu(1)-S(3) bond lengths. There are two shorter (3.02 Å) and two longer (3.10 Å) Eu(1)-S(2) bond lengths. P(1) is bonded in a tetrahedral geometry to one S(1), one S(3), and two equivalent S(2) atoms. The P(1)-S(1) bond length is 2.04 Å. The P(1)-S(3) bond length is 2.07 Å. Both P(1)-S(2) bond lengths are 2.06 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to three equivalent K(1), one Eu(1), and one P(1) atom to form distorted SK3EuP trigonal bipyramids that share corners with six equivalent S(2)K2Eu2P square pyramids, corners with six equivalent S(1)K3EuP trigonal bipyramids, and edges with six equivalent S(2)K2Eu2P square pyramids. In the second S site, S(2) is bonded to two equivalent K(1), two equivalent Eu(1), and one P(1) atom to form distorted SK2Eu2P square pyramids that share corners with six equivalent S(2)K2Eu2P square pyramids, corners with three equivalent S(1)K3EuP trigonal bipyramids, edges with two equivalent S(2)K2Eu2P square pyramids, edges with three equivalent S(1)K3EuP trigonal bipyramids, and  a faceface with one S(2)K2Eu2P square pyramid. In the third S site, S(3) is bonded in a 5-coordinate geometry to one K(1), three equivalent Eu(1), and one P(1) atom.