ChemInform Abstract: Extended Hückel Molecular Orbital Study of the Effects of Edge-Bridging Hydrogen Atoms on the Lengths of Boron-Boron and Metal-Metal Bonds in Cluster Compounds, and the Crystal Structure of Benzyltrimethylammonium Octahydrotriborate(1-).

ChemInform Abstract

The results of EHMO calculations are used to identify the cause of the general lengthening of B-B and M-M connectivities in clusters such as (I)-(V) as a consequence of H-bridging. The unusual relative shortening of the bridged B-B connectivities in B₃H₈^- is confirmed by an accurate, low-temp. (185 K) crystallographic study of the title compound (V) (space group P2₁/c, Z=4). The MO calculationsshow that the B-B edge shortening in B₃H₈^- is strongly correlated with the asym. nature of the H-bridges, and that these two distortions are mutually selfregulating.