K2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(6), one O(7), one O(8), one O(9), and two equivalent O(5) atoms. In the second K site, K(2) is bonded in a 10-coordinate geometry to one O(1), one O(13), one O(14), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(9) atom. In the third K site, K(3) is bonded in a 9-coordinate geometry to one O(10), one O(13), one O(14), one O(2), one O(6), one O(7), one O(8), and two equivalent O(12) atoms. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(14), one O(2), one O(8), and one O(9) atom. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. In the second Cr site, Cr(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing CrO4 tetrahedra. In the third Cr site, Cr(3) is bonded to one O(10), one O(11), one O(8), and one O(9) atom to form corner-sharing CrO4 tetrahedra. In the fourth Cr site, Cr(4) is bonded to one O(11), one O(12), one O(13), 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 distorted single-bond geometry to one K(1), one K(2), one K(4), and one Cr(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(2), one K(3), one K(4), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one K(2), one Cr(1), and one Cr(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one K(2), two equivalent K(1), and one Cr(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(3), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(3), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), one K(3), one K(4), and one Cr(3) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(4), and one Cr(3) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one K(3), one K(4), and one Cr(3) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one K(4), one Cr(3), and one Cr(4) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one K(4), two equivalent K(3), and one Cr(4) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one K(2), one K(3), and one Cr(4) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one K(2), one K(3), one K(4), and one Cr(4) atom.
K2Cr2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), one O(6), one O(7), one O(8), one O(9), and two equivalent O(5) atoms. The K(1)-O(1) bond length is 2.86 Å. The K(1)-O(3) bond length is 2.69 Å. The K(1)-O(6) bond length is 2.69 Å. The K(1)-O(7) bond length is 3.25 Å. The K(1)-O(8) bond length is 2.79 Å. The K(1)-O(9) bond length is 2.77 Å. There is one shorter (2.68 Å) and one longer (2.70 Å) K(1)-O(5) bond length. In the second K site, K(2) is bonded in a 10-coordinate geometry to one O(1), one O(13), one O(14), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(9) atom. The K(2)-O(1) bond length is 2.80 Å. The K(2)-O(13) bond length is 3.25 Å. The K(2)-O(14) bond length is 2.73 Å. The K(2)-O(2) bond length is 2.91 Å. The K(2)-O(3) bond length is 2.82 Å. The K(2)-O(4) bond length is 2.91 Å. The K(2)-O(5) bond length is 2.73 Å. The K(2)-O(6) bond length is 3.27 Å. The K(2)-O(7) bond length is 2.91 Å. The K(2)-O(9) bond length is 3.04 Å. In the third K site, K(3) is bonded in a 9-coordinate geometry to one O(10), one O(13), one O(14), one O(2), one O(6), one O(7), one O(8), and two equivalent O(12) atoms. The K(3)-O(10) bond length is 2.75 Å. The K(3)-O(13) bond length is 2.81 Å. The K(3)-O(14) bond length is 2.82 Å. The K(3)-O(2) bond length is 2.85 Å. The K(3)-O(6) bond length is 2.86 Å. The K(3)-O(7) bond length is 3.01 Å. The K(3)-O(8) bond length is 2.82 Å. There is one shorter (2.86 Å) and one longer (2.94 Å) K(3)-O(12) bond length. In the fourth K site, K(4) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(14), one O(2), one O(8), and one O(9) atom. The K(4)-O(1) bond length is 2.86 Å. The K(4)-O(10) bond length is 2.75 Å. The K(4)-O(11) bond length is 3.01 Å. The K(4)-O(12) bond length is 2.73 Å. The K(4)-O(14) bond length is 2.78 Å. The K(4)-O(2) bond length is 3.07 Å. The K(4)-O(8) bond length is 2.79 Å. The K(4)-O(9) bond length is 2.91 Å. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The Cr(1)-O(1) bond length is 1.62 Å. The Cr(1)-O(2) bond length is 1.62 Å. The Cr(1)-O(3) bond length is 1.61 Å. The Cr(1)-O(4) bond length is 1.78 Å. In the second Cr site, Cr(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing CrO4 tetrahedra. The Cr(2)-O(4) bond length is 1.77 Å. The Cr(2)-O(5) bond length is 1.62 Å. The Cr(2)-O(6) bond length is 1.62 Å. The Cr(2)-O(7) bond length is 1.61 Å. In the third Cr site, Cr(3) is bonded to one O(10), one O(11), one O(8), and one O(9) atom to form corner-sharing CrO4 tetrahedra. The Cr(3)-O(10) bond length is 1.61 Å. The Cr(3)-O(11) bond length is 1.77 Å. The Cr(3)-O(8) bond length is 1.63 Å. The Cr(3)-O(9) bond length is 1.62 Å. In the fourth Cr site, Cr(4) is bonded to one O(11), one O(12), one O(13), and one O(14) atom to form corner-sharing CrO4 tetrahedra. The Cr(4)-O(11) bond length is 1.78 Å. The Cr(4)-O(12) bond length is 1.62 Å. The Cr(4)-O(13) bond length is 1.61 Å. The Cr(4)-O(14) bond length is 1.62 Å. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(4), and one Cr(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to one K(2), one K(3), one K(4), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one K(1), one K(2), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one K(2), one Cr(1), and one Cr(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one K(2), two equivalent K(1), and one Cr(2) atom. In the sixth O site, O(6) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(3), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(3), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one K(1), one K(3), one K(4), and one Cr(3) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one K(1), one K(2), one K(4), and one Cr(3) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one K(3), one K(4), and one Cr(3) atom. In the eleventh O site, O(11) is bonded in a distorted bent 120 degrees geometry to one K(4), one Cr(3), and one Cr(4) atom. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one K(4), two equivalent K(3), and one Cr(4) atom. In the thirteenth O site, O(13) is bonded in a distorted single-bond geometry to one K(2), one K(3), and one Cr(4) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one K(2), one K(3), one K(4), and one Cr(4) atom.