Sr2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to one O(1), one O(10), one O(12), one O(2), one O(5), one O(6), one O(7), and two equivalent O(3) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(13), one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(3), one O(5), and one O(6) atom. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(13), one O(14), one O(7), one O(8), and two equivalent O(9) atoms. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(11), one O(2), one O(3), and one O(6) atom to form corner-sharing CrO4 tetrahedra. In the second Cr site, Cr(2) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form corner-sharing CrO4 tetrahedra. In the third Cr site, Cr(3) is bonded to one O(13), one O(4), one O(5), and one O(8) atom to form corner-sharing CrO4 tetrahedra. In the fourth Cr site, Cr(4) is bonded to one O(10), one O(11), one O(12), and one O(14) atom to form corner-sharing CrO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(4), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Sr(1) and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Sr(3), two equivalent Sr(1), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Sr(2), one Cr(2), and one Cr(3) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(2), one Sr(3), and one Cr(3) atom. In the sixth O site, O(6) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), and one Cr(1) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(2), one Sr(4), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Sr(2), one Sr(4), and one Cr(3) atom. In the ninth O site, O(9) is bonded to one Sr(2), two equivalent Sr(4), and one Cr(2) atom to form distorted edge-sharing OSr3Cr tetrahedra. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(3), one Sr(4), and one Cr(4) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one Sr(3), one Cr(1), and one Cr(4) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(3), and one Cr(4) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Sr(2), one Sr(3), one Sr(4), and one Cr(3) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal non-coplanar geometry to one Sr(3), one Sr(4), and one Cr(4) atom.
Sr2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 9-coordinate geometry to one O(1), one O(10), one O(12), one O(2), one O(5), one O(6), one O(7), and two equivalent O(3) atoms. The Sr(1)-O(1) bond length is 2.81 Å. The Sr(1)-O(10) bond length is 2.62 Å. The Sr(1)-O(12) bond length is 2.55 Å. The Sr(1)-O(2) bond length is 2.66 Å. The Sr(1)-O(5) bond length is 2.77 Å. The Sr(1)-O(6) bond length is 2.91 Å. The Sr(1)-O(7) bond length is 2.92 Å. There is one shorter (2.63 Å) and one longer (2.76 Å) Sr(1)-O(3) bond length. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(13), one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. The Sr(2)-O(13) bond length is 2.59 Å. The Sr(2)-O(4) bond length is 2.71 Å. The Sr(2)-O(5) bond length is 2.66 Å. The Sr(2)-O(6) bond length is 2.53 Å. The Sr(2)-O(7) bond length is 2.74 Å. The Sr(2)-O(8) bond length is 2.61 Å. The Sr(2)-O(9) bond length is 2.57 Å. In the third Sr site, Sr(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(3), one O(5), and one O(6) atom. The Sr(3)-O(10) bond length is 2.74 Å. The Sr(3)-O(11) bond length is 2.76 Å. The Sr(3)-O(12) bond length is 2.55 Å. The Sr(3)-O(13) bond length is 2.71 Å. The Sr(3)-O(14) bond length is 2.63 Å. The Sr(3)-O(3) bond length is 2.63 Å. The Sr(3)-O(5) bond length is 2.82 Å. The Sr(3)-O(6) bond length is 2.63 Å. In the fourth Sr site, Sr(4) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(13), one O(14), one O(7), one O(8), and two equivalent O(9) atoms. The Sr(4)-O(1) bond length is 2.56 Å. The Sr(4)-O(10) bond length is 2.92 Å. The Sr(4)-O(13) bond length is 2.73 Å. The Sr(4)-O(14) bond length is 2.51 Å. The Sr(4)-O(7) bond length is 2.82 Å. The Sr(4)-O(8) bond length is 2.53 Å. There is one shorter (2.58 Å) and one longer (2.61 Å) Sr(4)-O(9) bond length. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(11), one O(2), one O(3), and one O(6) atom to form corner-sharing CrO4 tetrahedra. The Cr(1)-O(11) bond length is 1.82 Å. The Cr(1)-O(2) bond length is 1.66 Å. The Cr(1)-O(3) bond length is 1.70 Å. The Cr(1)-O(6) bond length is 1.74 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form corner-sharing CrO4 tetrahedra. The Cr(2)-O(1) bond length is 1.68 Å. The Cr(2)-O(4) bond length is 1.82 Å. The Cr(2)-O(7) bond length is 1.68 Å. The Cr(2)-O(9) bond length is 1.74 Å. In the third Cr site, Cr(3) is bonded to one O(13), one O(4), one O(5), and one O(8) atom to form corner-sharing CrO4 tetrahedra. The Cr(3)-O(13) bond length is 1.70 Å. The Cr(3)-O(4) bond length is 1.81 Å. The Cr(3)-O(5) bond length is 1.73 Å. The Cr(3)-O(8) bond length is 1.68 Å. In the fourth Cr site, Cr(4) is bonded to one O(10), one O(11), one O(12), and one O(14) atom to form corner-sharing CrO4 tetrahedra. The Cr(4)-O(10) bond length is 1.71 Å. The Cr(4)-O(11) bond length is 1.81 Å. The Cr(4)-O(12) bond length is 1.68 Å. The Cr(4)-O(14) bond length is 1.72 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(4), and one Cr(2) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one Sr(1) and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Sr(3), two equivalent Sr(1), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Sr(2), one Cr(2), and one Cr(3) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(2), one Sr(3), and one Cr(3) atom. In the sixth O site, O(6) is bonded in a 1-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), and one Cr(1) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(2), one Sr(4), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a distorted trigonal planar geometry to one Sr(2), one Sr(4), and one Cr(3) atom. In the ninth O site, O(9) is bonded to one Sr(2), two equivalent Sr(4), and one Cr(2) atom to form distorted edge-sharing OSr3Cr tetrahedra. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Sr(1), one Sr(3), one Sr(4), and one Cr(4) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one Sr(3), one Cr(1), and one Cr(4) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Sr(1), one Sr(3), and one Cr(4) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Sr(2), one Sr(3), one Sr(4), and one Cr(3) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal non-coplanar geometry to one Sr(3), one Sr(4), and one Cr(4) atom.