NaK(BH4)2 crystallizes in the trigonal R-3m space group. K(1) is bonded to twelve equivalent H(2) atoms to form KH12 cuboctahedra that share edges with six equivalent K(1)H12 cuboctahedra, edges with six equivalent Na(1)H12 cuboctahedra, and edges with six equivalent B(1)H4 tetrahedra. Na(1) is bonded to six equivalent H(1) and six equivalent H(2) atoms to form distorted NaH12 cuboctahedra that share edges with six equivalent K(1)H12 cuboctahedra, edges with six equivalent Na(1)H12 cuboctahedra, and edges with six equivalent B(1)H4 tetrahedra. B(1) is bonded to one H(1) and three equivalent H(2) atoms to form BH4 tetrahedra that share edges with three equivalent K(1)H12 cuboctahedra and edges with three equivalent Na(1)H12 cuboctahedra. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to three equivalent Na(1) and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to two equivalent K(1), one Na(1), and one B(1) atom.
NaK(BH4)2 crystallizes in the trigonal R-3m space group. K(1) is bonded to twelve equivalent H(2) atoms to form KH12 cuboctahedra that share edges with six equivalent K(1)H12 cuboctahedra, edges with six equivalent Na(1)H12 cuboctahedra, and edges with six equivalent B(1)H4 tetrahedra. All K(1)-H(2) bond lengths are 2.79 Å. Na(1) is bonded to six equivalent H(1) and six equivalent H(2) atoms to form distorted NaH12 cuboctahedra that share edges with six equivalent K(1)H12 cuboctahedra, edges with six equivalent Na(1)H12 cuboctahedra, and edges with six equivalent B(1)H4 tetrahedra. All Na(1)-H(1) bond lengths are 2.67 Å. All Na(1)-H(2) bond lengths are 2.44 Å. B(1) is bonded to one H(1) and three equivalent H(2) atoms to form BH4 tetrahedra that share edges with three equivalent K(1)H12 cuboctahedra and edges with three equivalent Na(1)H12 cuboctahedra. The B(1)-H(1) bond length is 1.22 Å. All B(1)-H(2) bond lengths are 1.23 Å. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to three equivalent Na(1) and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to two equivalent K(1), one Na(1), and one B(1) atom.