Dy2CoSi2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 6-coordinate geometry to two equivalent Co(1), one Si(2), and five equivalent Si(1) atoms. In the second Dy site, Dy(2) is bonded in a 10-coordinate geometry to four equivalent Co(1), two equivalent Si(1), and five equivalent Si(2) atoms. Co(1) is bonded in a 10-coordinate geometry to two equivalent Dy(1), four equivalent Dy(2), one Si(1), and three equivalent Si(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Dy(2), five equivalent Dy(1), one Co(1), and one Si(1) atom. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Dy(1), five equivalent Dy(2), three equivalent Co(1), and one Si(2) atom.
Dy2CoSi2 crystallizes in the monoclinic C2/m space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 6-coordinate geometry to two equivalent Co(1), one Si(2), and five equivalent Si(1) atoms. Both Dy(1)-Co(1) bond lengths are 3.27 Å. The Dy(1)-Si(2) bond length is 2.89 Å. There are a spread of Dy(1)-Si(1) bond distances ranging from 2.94-3.10 Å. In the second Dy site, Dy(2) is bonded in a 10-coordinate geometry to four equivalent Co(1), two equivalent Si(1), and five equivalent Si(2) atoms. There are a spread of Dy(2)-Co(1) bond distances ranging from 2.93-3.08 Å. Both Dy(2)-Si(1) bond lengths are 2.89 Å. There are a spread of Dy(2)-Si(2) bond distances ranging from 2.96-3.19 Å. Co(1) is bonded in a 10-coordinate geometry to two equivalent Dy(1), four equivalent Dy(2), one Si(1), and three equivalent Si(2) atoms. The Co(1)-Si(1) bond length is 2.46 Å. There are two shorter (2.34 Å) and one longer (2.39 Å) Co(1)-Si(2) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a 9-coordinate geometry to two equivalent Dy(2), five equivalent Dy(1), one Co(1), and one Si(1) atom. The Si(1)-Si(1) bond length is 2.54 Å. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Dy(1), five equivalent Dy(2), three equivalent Co(1), and one Si(2) atom. The Si(2)-Si(2) bond length is 2.76 Å.