Intercluster B-H and B-B aggregation in iso- and -[BH]. Spherical aromaticity in borane dimers.

The formation of molecular-based functional materials is a key step towards the development of technologies at the nanoscale. Recently, it has been shown that after oxidation of -[BH] anions, an induced aggregation of two cluster units is achieved, retaining their parent B backbones as persistent building blocks. Such characterization provides an interesting scenario to further understand relevant factors leading to aggregation in a minimal structure involving two units. Here, we explore the interaction between -[BH] units in two isomers, namely, iso- and -[BH], involving different intercluster contacts based on B-B and B-H interactions, respectively. Our results show that the inherent spherical aromatic characteristics of the parent -[BH] cluster are persistent in both iso- and -[BH] isomers as an interplay between the spherical aromatic properties from both B motifs, leading to an overlap of the shielding regions from shielding cone properties, ascribed as a dual spherical-spherical aromatic cluster. From B-NMR features, it came out that -[BH] involves larger differences in comparison to -[BH], owing to the variation of the B-B backbone provided by the intercluster B-interaction, thus resulting in a more effective aggregation connecting such building units, towards boron-based cluster materials.