NaK(BH4)2 crystallizes in the trigonal R-3 space group. K(1) is bonded to six equivalent H(1) and six equivalent H(2) atoms to form KH12 cuboctahedra that share corners with six equivalent Na(1)H6 octahedra, edges with six equivalent K(1)H12 cuboctahedra, and edges with six equivalent B(1)H4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. Na(1) is bonded to six equivalent H(2) atoms to form NaH6 octahedra that share corners with six equivalent K(1)H12 cuboctahedra and corners 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 corners with three equivalent Na(1)H6 octahedra and edges with three equivalent K(1)H12 cuboctahedra. The corner-sharing octahedral tilt angles are 66°. There are two inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to three equivalent K(1) and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one K(1), one Na(1), and one B(1) atom.
NaK(BH4)2 crystallizes in the trigonal R-3 space group. K(1) is bonded to six equivalent H(1) and six equivalent H(2) atoms to form KH12 cuboctahedra that share corners with six equivalent Na(1)H6 octahedra, edges with six equivalent K(1)H12 cuboctahedra, and edges with six equivalent B(1)H4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. All K(1)-H(1) bond lengths are 2.72 Å. All K(1)-H(2) bond lengths are 2.82 Å. Na(1) is bonded to six equivalent H(2) atoms to form NaH6 octahedra that share corners with six equivalent K(1)H12 cuboctahedra and corners with six equivalent B(1)H4 tetrahedra. All Na(1)-H(2) bond lengths are 2.42 Å. B(1) is bonded to one H(1) and three equivalent H(2) atoms to form BH4 tetrahedra that share corners with three equivalent Na(1)H6 octahedra and edges with three equivalent K(1)H12 cuboctahedra. The corner-sharing octahedral tilt angles are 66°. The B(1)-H(1) bond length is 1.23 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 K(1) and one B(1) atom. In the second H site, H(2) is bonded in a distorted single-bond geometry to one K(1), one Na(1), and one B(1) atom.