Cr5(Si2O7)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted linear geometry to two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms. In the second Cr site, Cr(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(7) atom. In the third Cr site, Cr(3) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(7), and two equivalent O(6) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted water-like geometry to one O(2), one O(3), one O(4), and one O(7) atom. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(5), and one O(6) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Cr(2) and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Cr(1), one Cr(2), one Cr(3), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Cr(3) and one Si(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Cr(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Cr(1), one Cr(2), one Cr(3), and one Si(1) atom.
Cr5(Si2O7)2 crystallizes in the triclinic P-1 space group. There are three inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted linear geometry to two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms. Both Cr(1)-O(2) bond lengths are 2.64 Å. Both Cr(1)-O(5) bond lengths are 1.97 Å. Both Cr(1)-O(7) bond lengths are 2.71 Å. In the second Cr site, Cr(2) is bonded in a 4-coordinate geometry to one O(1), one O(2), one O(5), and one O(7) atom. The Cr(2)-O(1) bond length is 1.90 Å. The Cr(2)-O(2) bond length is 1.87 Å. The Cr(2)-O(5) bond length is 2.46 Å. The Cr(2)-O(7) bond length is 2.34 Å. In the third Cr site, Cr(3) is bonded in a 5-coordinate geometry to one O(2), one O(4), one O(7), and two equivalent O(6) atoms. The Cr(3)-O(2) bond length is 2.54 Å. The Cr(3)-O(4) bond length is 2.40 Å. The Cr(3)-O(7) bond length is 1.90 Å. There is one shorter (2.02 Å) and one longer (2.24 Å) Cr(3)-O(6) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded in a distorted water-like geometry to one O(2), one O(3), one O(4), and one O(7) atom. The Si(1)-O(2) bond length is 2.14 Å. The Si(1)-O(3) bond length is 1.38 Å. The Si(1)-O(4) bond length is 1.25 Å. The Si(1)-O(7) bond length is 2.20 Å. In the second Si site, Si(2) is bonded in a 4-coordinate geometry to one O(1), one O(3), one O(5), and one O(6) atom. The Si(2)-O(1) bond length is 1.32 Å. The Si(2)-O(3) bond length is 1.88 Å. The Si(2)-O(5) bond length is 2.36 Å. The Si(2)-O(6) bond length is 1.49 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Cr(2) and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Cr(1), one Cr(2), one Cr(3), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(4) is bonded in a single-bond geometry to one Cr(3) and one Si(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Cr(1), one Cr(2), and one Si(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Cr(3) and one Si(2) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Cr(1), one Cr(2), one Cr(3), and one Si(1) atom.