SOLVATION EFFECTS ON GEOMETRY AND CHEMICAL-SHIFTS - AN ABINITIO IGLO RECONCILIATION OF APPARENT EXPERIMENTAL INCONSISTENCIES ON H3B.NH3

To what extent can the structural parameters of a molecule be altered by the surrounding medium? According to model calculations in a polar solvent continuum, the BN bond length in H3B.NH3 in aqueous solution is indicated to be shortened by ca. 0.1 angstrom over the value in the gas phase (1.672 angstrom, microwave), i.e. to nearly the BN separation in the solid state (1.564 angstrom, X-ray). Similar calculations with the solvent hexane gave a value of 1.62 angstrom.