1,3-Dipolar cycloaddition of BC2N nanotubes: A DFT study

It seems the isolated CC units in the zigzag BC2N nanotubes could be considered as preactivated sites for exohedral functionalization. Therefore, we theoretically investigate the [2+3] cycloaddition reactions of 1,3 dipoles (1,3 DCs) such as nitriloxide (HCN+O−), azide (NN+NH−) and azomethine ylides ( H 2 C NH + CH 2 - ) with BC2N nanotubes in terms of geometry, energies, and electronic structures. Negative values of 1,3 DC reaction energies indicate the exothermic character of adsorption process of BC2N nanotubes. Our results show the ZZ-3 (n, 0) BC2N nanotubes in which borons and nitrogens are located in trans positions of CC double bonds lead to the most energetically favorable configuration for 1,3 DC products. Further, Er values for different (n, 0) BC2N nanotubes are in the series of (3,0) < (4,0) < (5,0), indicating BC2N-NTs with smaller diameter (higher curvature) might be more favorable because of both energetic and structural considerations. Er values for different 1,3 dipoles are in the series of ( H 2 C NH + CH 2 - ) < (HCN+O−)< (NN+NH−), in agreement with the distortion/interaction model for the cycloaddition reactions. Variation of HOMO–LUMO gaps (Eg) for 1,3 DC products shows a decreasing trend with increasing of tube diameter while Eg is almost independent of the type of 1,3 dipoles.