Mg6NiSi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ni(1), and two equivalent Si(1) atoms to form a mixture of distorted edge, face, and corner-sharing MgMg8Si2Ni2 cuboctahedra. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent Mg(1), two equivalent Ni(1), and two equivalent Si(1) atoms. In the third Mg site, Mg(3) is bonded in a distorted water-like geometry to four equivalent Mg(1) and two equivalent Ni(1) atoms. In the fourth Mg site, Mg(4) is bonded in a distorted water-like geometry to four equivalent Mg(1) and two equivalent Si(1) atoms. Ni(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms. Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms.
Mg6NiSi crystallizes in the orthorhombic Amm2 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), two equivalent Mg(3), two equivalent Mg(4), two equivalent Ni(1), and two equivalent Si(1) atoms to form a mixture of distorted edge, face, and corner-sharing MgMg8Si2Ni2 cuboctahedra. There is one shorter (3.06 Å) and one longer (3.10 Å) Mg(1)-Mg(1) bond length. Both Mg(1)-Mg(2) bond lengths are 2.96 Å. Both Mg(1)-Mg(3) bond lengths are 2.96 Å. Both Mg(1)-Mg(4) bond lengths are 2.95 Å. There is one shorter (2.99 Å) and one longer (3.03 Å) Mg(1)-Ni(1) bond length. There is one shorter (2.98 Å) and one longer (3.03 Å) Mg(1)-Si(1) bond length. In the second Mg site, Mg(2) is bonded in a 4-coordinate geometry to two equivalent Mg(1), two equivalent Ni(1), and two equivalent Si(1) atoms. Both Mg(2)-Ni(1) bond lengths are 2.90 Å. Both Mg(2)-Si(1) bond lengths are 2.96 Å. In the third Mg site, Mg(3) is bonded in a distorted water-like geometry to four equivalent Mg(1) and two equivalent Ni(1) atoms. Both Mg(3)-Ni(1) bond lengths are 2.87 Å. In the fourth Mg site, Mg(4) is bonded in a distorted water-like geometry to four equivalent Mg(1) and two equivalent Si(1) atoms. Both Mg(4)-Si(1) bond lengths are 2.89 Å. Ni(1) is bonded in a 10-coordinate geometry to two equivalent Mg(3), four equivalent Mg(1), and four equivalent Mg(2) atoms. Si(1) is bonded in a 10-coordinate geometry to two equivalent Mg(4), four equivalent Mg(1), and four equivalent Mg(2) atoms.