COMPUTATIONAL METHODS
Planar BxNx (x = 2 – 11) clusters were optimized at the PBE048/def2-TZVP49level of theory using Gaussian 09 computational package50. For the fully optimized molecules, vibrational frequency calculations were performed at the same level to ensure that we obtained a true minimum on the potential energy surface. NICSzz values were computed employing the Gauge-Including Atomic Orbital (GIAO) in gas phase at the above-mentioned level. Ring current strength (RCS) calculations were done using AIMAll51 software. Chemical bond was analysed through Adaptative Natural Density Partitioning (AdNDP), this method is a generalization of NBO method. AdNDP recovers Lewis bonding (1c-2e lone pairs, 2c-2e two electron bonds), additionally, localized bonds associated with (anti)aromaticity. NICSzz scans, FiPC and NICSzz isosurfaces and AdNDP orbitals were obtained using our own routines and Multiwfn software52. Visualization of NICSzzisosurfaces and NICSzz isolines have been plotted using Chemcraft and VisIt 2.13.0 respectively53,54.