CRYSTAL STRUCTURE OF TETRAAMMINEZINC OCTAHYDROOCTABORATE(-2), ZN(NH3)4B8H8

The molecular and crystal structures of tetraamminezinc octahydrooctaborate(-2), Zn(NH3)4B8H8, have been determined from three-dimensional X-ray counter data. This compound crystallizes in the tetragonal space group P42/nmc with two molecules in a cell of dimensions a = 7.503 ± 0.005 and c = 10.784 ± 0.008 Å. The structure was refined by least-squares procedures to a conventional R of 0.078. The structure contains Zn(NH3)42+ cations and B8H82- anions. The B8H82- polyhedron is a distorted dodecahedron of D2d (̅42m) point symmetry similar to that observed in the B8Cl8 and B6H6C2(CH3)2 structures. Molecular orbital calculations indicate that the five-coordinate boron atoms are the more negative of the two sets of five- and six-coordinate boron atoms. © 1969, American Chemical Society. All rights reserved.