Fig. 1: Mass spectrometric proof of the Bi5− anion in solution as well as its molecular and electronic structure including π-aromatic features according to quantum chemical studies in comparison with (C5H5)−.
From: Isolation of a planar π-aromatic Bi5− ring in a cobalt-based inverse-sandwich-type complex
a, ESI mass spectrum in negative ion mode of the reaction solution prepared from [K(crypt-222)]2Bi2 and BiI3 (2:1) in en, with the molecular peak of Bi5− at m/z = 1,044.9 being the clearly predominant signal; the inset spectrum zooms into the high resolution of the mass peak as measured (top) and calculated (bottom). The molecules shown top right are the two most energetically favourable isomers of Bi5−, a planar ring (D5h), and a capped butterfly-type isomer (C2v, +30 kJ mol−1), according to DFT calculations. b, Energies and amplitudes of p-orbital-based valence MOs of Bi5− (left) and (C5H5)− (right), with different superatomic MO types (albeit of a two-dimensional molecule) specified by different colours of bars and Mulliken symbols: s-type (red), p-type (black), d-type (orange) and f-type (blue); contours are drawn at ±0.04 a.u.; full-valence MO diagrams are shown in Supplementary Fig. 1. c, Top and centre: amplitudes of LMOs of Bi5− (left) and (C5H5)− (right); contours are drawn at ±0.05 a.u.; in the upper row, only one representative of each of the five equivalent LMOs is shown. Bottom: contour plot of the absolute value of the magnetically induced current density, drawn at 0.025 a.u.; contours for paratropic currents are drawn in blue, and those for diatropic currents are drawn in red.
