Theoretical investigation on geometries and aromaticity of mixed boron-, nitrogen- and furanoxo-containing five-membered rings B2N2OHp (p = 0-2)

We have calculated geometries, aromaticity, enthalpies of formation and combustion, the proton and hydride affinities for the predicted five-membered ring high energetic compounds B2N2OHp (p = 0-2) which contain boron, nitrogen and furanoxo group employing the B3LYP/aug-cc-pVTZ, MP2/aug-cc-pVTZ, G2 and G3 methods. Only eleven five-membered ring structures were obtained as minima at the potential energy surfaces. All compounds have large negative NICS values and the strong aromatic properties. It reveals that the incorporation of the furanoxo group into the ringed high energetic boron-nitrogen compounds can improve the aromaticity and stabilities. As the high energetic compounds, the enthalpies of formation and the combustion are 42.4-146.9 kJ/mol and 10-31 kJ/g at G2 level, respectively, which are close to those of the three-membered boron-nitrogen high energetic compounds. The hydride affinities are lower than the proton affinities, indicating that the Lewis acidity of the compounds B2N2OHp (p = 0-2) is weaker than the Lewis basicity. The results of the proton and hydride affinities may also predict that the electrophilic reagent prefers to bind to the nitrogen atom at the ortho-position of furanoxo group while the nucleophilic reagent inclines to bind to the boron atom at the meta-position of furanoxo group.