Structure of Cu2B10H10

An x-ray diffraction study of the crystal structure of Cu2B10H10 shows that the earlier proposal that the B10H10—2 ion has D4d symmetry is correct, and further establishes the covalent nature of the interactions of CuI with B atoms forming the edges of the polyhedron. There are eight Cu2B10H10 in a unit cell having dimensions a = 10.11, b = 11.36, and c = 14.50, and the space group is Pcab. Bonds within a tetragonal pyramid are 1.73 Å (to apex) and 1.86 Å (along base), while B–B bonds between the tetragonal pyramids are 1.81 Å in length. The closest Cu···B distances range from 2.14 to 2.33 Å in length.