Solvent effects on one-bond B-Li coupling constants in boryllithium compounds

EOM-CCSD 11B-7Li coupling constants and B chemical shifts have been computed for Li-diazaborole and its complexes with one H2O or FLi molecule. B-Li coupling constants for a model compound H(2)BLi and its complexes with up to 4 H2O or FLi molecules have also been obtained in an attempt to resolve discrepancies between the computed values of these properties for isolated Li-diazaborole and experimentally determined values for boryllithium in a THF solution. The presence of solvent molecules increases the ion-pair character of the B-Li bond, with the result that 1J(B-Li) decreases systematically as the basicity and the number of solvent molecules increases. In the presence of even a single solvent molecule, the boron chemical shift for Li-diazaborole increases, and approaches the experimental value. The computed results emphasize the role of the solvent in determining these NMR properties.