K3AlH6 crystallizes in the orthorhombic Pnnm space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one H(3), two equivalent H(1), two equivalent H(2), and two equivalent H(4) atoms. In the second K site, K(2) is bonded in a 5-coordinate geometry to one H(4), two equivalent H(2), and two equivalent H(5) atoms. In the third K site, K(3) is bonded in a 7-coordinate geometry to one H(1), one H(2), one H(6), two equivalent H(4), and two equivalent H(5) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent H(5) and four equivalent H(6) atoms to form edge-sharing AlH6 octahedra. In the second Al site, Al(2) is bonded to two equivalent H(1) and four equivalent H(3) atoms to form edge-sharing AlH6 octahedra. There are six inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one K(3), two equivalent K(1), and one Al(2) atom. In the second H site, H(2) is bonded to one K(3), two equivalent K(1), and two equivalent K(2) atoms to form a mixture of distorted corner and edge-sharing HK5 square pyramids. In the third H site, H(3) is bonded in a distorted trigonal non-coplanar geometry to one K(1) and two equivalent Al(2) atoms. In the fourth H site, H(4) is bonded to one K(2), two equivalent K(1), and two equivalent K(3) atoms to form a mixture of distorted corner and edge-sharing HK5 trigonal bipyramids. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to two equivalent K(2), two equivalent K(3), and one Al(1) atom. In the sixth H site, H(6) is bonded in a distorted water-like geometry to one K(3) and two equivalent Al(1) atoms.
K3AlH6 crystallizes in the orthorhombic Pnnm space group. There are three inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one H(3), two equivalent H(1), two equivalent H(2), and two equivalent H(4) atoms. The K(1)-H(3) bond length is 2.77 Å. Both K(1)-H(1) bond lengths are 2.89 Å. Both K(1)-H(2) bond lengths are 2.57 Å. Both K(1)-H(4) bond lengths are 2.55 Å. In the second K site, K(2) is bonded in a 5-coordinate geometry to one H(4), two equivalent H(2), and two equivalent H(5) atoms. The K(2)-H(4) bond length is 2.63 Å. Both K(2)-H(2) bond lengths are 2.53 Å. Both K(2)-H(5) bond lengths are 2.95 Å. In the third K site, K(3) is bonded in a 7-coordinate geometry to one H(1), one H(2), one H(6), two equivalent H(4), and two equivalent H(5) atoms. The K(3)-H(1) bond length is 2.92 Å. The K(3)-H(2) bond length is 2.60 Å. The K(3)-H(6) bond length is 2.93 Å. Both K(3)-H(4) bond lengths are 2.53 Å. Both K(3)-H(5) bond lengths are 2.84 Å. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent H(5) and four equivalent H(6) atoms to form edge-sharing AlH6 octahedra. Both Al(1)-H(5) bond lengths are 1.67 Å. All Al(1)-H(6) bond lengths are 1.97 Å. In the second Al site, Al(2) is bonded to two equivalent H(1) and four equivalent H(3) atoms to form edge-sharing AlH6 octahedra. Both Al(2)-H(1) bond lengths are 1.65 Å. All Al(2)-H(3) bond lengths are 1.97 Å. There are six inequivalent H sites. In the first H site, H(1) is bonded in a distorted single-bond geometry to one K(3), two equivalent K(1), and one Al(2) atom. In the second H site, H(2) is bonded to one K(3), two equivalent K(1), and two equivalent K(2) atoms to form a mixture of distorted corner and edge-sharing HK5 square pyramids. In the third H site, H(3) is bonded in a distorted trigonal non-coplanar geometry to one K(1) and two equivalent Al(2) atoms. In the fourth H site, H(4) is bonded to one K(2), two equivalent K(1), and two equivalent K(3) atoms to form a mixture of distorted corner and edge-sharing HK5 trigonal bipyramids. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to two equivalent K(2), two equivalent K(3), and one Al(1) atom. In the sixth H site, H(6) is bonded in a distorted water-like geometry to one K(3) and two equivalent Al(1) atoms.