Eu2CoSi3 is hexagonal omega structure-derived structured and crystallizes in the hexagonal P-6m2 space group. Eu(1) is bonded to three equivalent Co(1), three equivalent Si(1), three equivalent Si(2), and three equivalent Si(3) atoms to form a mixture of face and edge-sharing EuCo3Si9 cuboctahedra. Co(1) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Si(2) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Si(3) atoms. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Co(1) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Si(1) atoms.
Eu2CoSi3 is hexagonal omega structure-derived structured and crystallizes in the hexagonal P-6m2 space group. Eu(1) is bonded to three equivalent Co(1), three equivalent Si(1), three equivalent Si(2), and three equivalent Si(3) atoms to form a mixture of face and edge-sharing EuCo3Si9 cuboctahedra. All Eu(1)-Co(1) bond lengths are 3.13 Å. All Eu(1)-Si(1) bond lengths are 3.25 Å. All Eu(1)-Si(2) bond lengths are 3.13 Å. All Eu(1)-Si(3) bond lengths are 3.25 Å. Co(1) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Si(2) atoms. All Co(1)-Si(2) bond lengths are 2.31 Å. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Si(3) atoms. All Si(1)-Si(3) bond lengths are 2.31 Å. In the second Si site, Si(2) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Co(1) atoms. In the third Si site, Si(3) is bonded in a 9-coordinate geometry to six equivalent Eu(1) and three equivalent Si(1) atoms.