Ba2NiSi3 crystallizes in the hexagonal P-62m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent Ni(1), two equivalent Si(1), and eight equivalent Si(2) atoms to form a mixture of distorted corner and face-sharing BaSi10Ni2 cuboctahedra. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Ni(2), four equivalent Si(1), and four equivalent Si(2) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 9-coordinate geometry to three equivalent Ba(1) and six equivalent Si(2) atoms. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to three equivalent Ba(2) and six equivalent Si(1) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted q6 geometry to two equivalent Ba(1), four equivalent Ba(2), two equivalent Ni(2), and two equivalent Si(1) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to two equivalent Ba(2), four equivalent Ba(1), two equivalent Ni(1), and two equivalent Si(2) atoms.
Ba2NiSi3 crystallizes in the hexagonal P-62m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded to two equivalent Ni(1), two equivalent Si(1), and eight equivalent Si(2) atoms to form a mixture of distorted corner and face-sharing BaSi10Ni2 cuboctahedra. Both Ba(1)-Ni(1) bond lengths are 3.58 Å. Both Ba(1)-Si(1) bond lengths are 3.57 Å. There are four shorter (3.67 Å) and four longer (3.69 Å) Ba(1)-Si(2) bond lengths. In the second Ba site, Ba(2) is bonded in a 9-coordinate geometry to one Ni(2), four equivalent Si(1), and four equivalent Si(2) atoms. The Ba(2)-Ni(2) bond length is 3.30 Å. All Ba(2)-Si(1) bond lengths are 3.46 Å. All Ba(2)-Si(2) bond lengths are 3.35 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 9-coordinate geometry to three equivalent Ba(1) and six equivalent Si(2) atoms. All Ni(1)-Si(2) bond lengths are 2.39 Å. In the second Ni site, Ni(2) is bonded in a 9-coordinate geometry to three equivalent Ba(2) and six equivalent Si(1) atoms. All Ni(2)-Si(1) bond lengths are 2.39 Å. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted q6 geometry to two equivalent Ba(1), four equivalent Ba(2), two equivalent Ni(2), and two equivalent Si(1) atoms. Both Si(1)-Si(1) bond lengths are 2.42 Å. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to two equivalent Ba(2), four equivalent Ba(1), two equivalent Ni(1), and two equivalent Si(2) atoms. Both Si(2)-Si(2) bond lengths are 2.41 Å.