Molecular structures of tetraborane(10) derivatives: ab initio calculations for H2MB3H8 (M = B, Al, Ga or In) and gas-phase electron diffraction study of H2GaB3H8

Abstract

Structural trends in the family of compounds H₂MB₃H₈ (M = B, Al, Ga or In) have been investigated by ab initio molecular orbital calculations. In addition, the molecular structure of the arachno borane H₂GaB₃H₈ has been re-determined by gas-phase electron diffraction using the SARACEN method of structural analysis. Salient structural parameters (r_α⁰) were found to be: r[B(1)· · ·Ga(2)] 231.0(2), r[B(1)–B(3)] 177.9(13), r[B(1)–B(4)] 184.0(13), r[B(1)–H(1,2)] 123.0(11), r[Ga(2)–H(1,2)] 181(4), r[B(1)–H(1,4)] 123.7(11), r[B(4)–H(1,4)] 142.2(18) pm; butterfly angle 117.1(7)°.