CaH2 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded in a 11-coordinate geometry to five equivalent H(1) and six equivalent H(2) atoms. There are two inequivalent H sites. In the first H site, H(1) is bonded to five equivalent Ca(1) atoms to form distorted HCa5 trigonal bipyramids that share corners with twelve equivalent H(2)Ca6 octahedra, corners with eight equivalent H(1)Ca5 trigonal bipyramids, edges with six equivalent H(1)Ca5 trigonal bipyramids, and faces with six equivalent H(2)Ca6 octahedra. The corner-sharing octahedral tilt angles range from 31-59°. In the second H site, H(2) is bonded to six equivalent Ca(1) atoms to form HCa6 octahedra that share corners with twelve equivalent H(2)Ca6 octahedra, corners with twelve equivalent H(1)Ca5 trigonal bipyramids, edges with six equivalent H(2)Ca6 octahedra, faces with two equivalent H(2)Ca6 octahedra, and faces with six equivalent H(1)Ca5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-51°.
CaH2 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded in a 11-coordinate geometry to five equivalent H(1) and six equivalent H(2) atoms. There are three shorter (2.20 Å) and two longer (2.67 Å) Ca(1)-H(1) bond lengths. There are four shorter (2.56 Å) and two longer (2.59 Å) Ca(1)-H(2) bond lengths. There are two inequivalent H sites. In the first H site, H(1) is bonded to five equivalent Ca(1) atoms to form distorted HCa5 trigonal bipyramids that share corners with twelve equivalent H(2)Ca6 octahedra, corners with eight equivalent H(1)Ca5 trigonal bipyramids, edges with six equivalent H(1)Ca5 trigonal bipyramids, and faces with six equivalent H(2)Ca6 octahedra. The corner-sharing octahedral tilt angles range from 31-59°. In the second H site, H(2) is bonded to six equivalent Ca(1) atoms to form HCa6 octahedra that share corners with twelve equivalent H(2)Ca6 octahedra, corners with twelve equivalent H(1)Ca5 trigonal bipyramids, edges with six equivalent H(2)Ca6 octahedra, faces with two equivalent H(2)Ca6 octahedra, and faces with six equivalent H(1)Ca5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 50-51°.