Analysis of Local and Global Aromaticity in Si3C5 and Si4C8 Clusters. Aromatic Species Containing Planar Tetracoordinate Carbon

Abstract

The minimum energy structures of the Si3C5 and Si4C8 clusters are planar and contain planar tetracoordinate carbons (ptCs). These species have been classified, qualitatively, as global (π) and local (σ) aromatics according to the adaptive natural density partitioning (AdNDP) method, which is an orbital localization method. This work evaluates these species’ aromaticity, focusing on confirming and quantifying their global and local aromatic character. For this purpose, we use an orbital localization method based on the partitioning of the molecular space according to the topology of the electronic localization function (LOC-ELF). In addition, the magnetically induced current density is analyzed. The LOC-ELF-based analysis coincides with the AdNDP study (double aromaticity, global, and local). Moreover, the current density analysis detects global and local ring currents. The strength of the global and local current circuit is significant, involving 4n + 2 π- and σ-electrons, respectively. The latter implicates the Si-ptC-Si fragment, which would be related to the 3c-2e σ-bond detected by the orbital localization methods in this fragment.

Persistent Planar Tetracoordinate Carbon in Global Minima Structures of Silicon-Carbon Clusters

“…The analysis used to identify the different ring current circuits has been performed according to the strategy initially proposed in references [46,59], which consists of establishing equations that account for the couplings of the different current flows. Note that this strategy has been used satisfactorily in our group in different recent works [60,61]. The integration planes used and the RCS values (total and partial: profiles) are reported in Figures S3-S5 in the Supplementary Material.…”

Si6C18: A bispentalene derivative with two planar tetracoordinate carbons

“…C 18 H 10 2À , which is a local minimum, exhibits a weak global aromatic character but retains the local antiaromaticity of the neutral system. Figure 1 shows a schematic representation of the detected ring currents, following a previously proposed methodology [36,41,60,72], by analyzing the profiles of different integration planes (see Figure S3). What happens when replacing the ten H + of C 18 H 10 2À with six Si 2+ ?…”

Enabling dual aromaticity in fused nanobelts: evaluation of the magnetic behavior of fused [10]CPP units

“…Our results through induced magnetic field maps extend the understanding of the characteristics of the shielding cone at fused nanobelt structures, providing an evaluation under different orientations of the applied field, indicating its global aromatic behavior. 36–40 In addition, the particular anisotropy effect in such species is discussed, accounting for both short- and long-range anisotropy cones influencing the shielding of guest atoms or molecules. 36,41–44…”

“…Our results through induced magnetic field maps extend the understanding of the characteristics of the shielding cone at fused nanobelt structures, providing an evaluation under different orientations of the applied field, indicating its global aromatic behavior. [36][37][38][39][40] In addition, the particular anisotropy effect in such species is discussed, accounting for both short-and long-range anisotropy cones influencing the shielding of guest atoms or molecules. 36,[41][42][43][44] code 45 with the all-electron triple-x slater basis set plus the double-polarization (STO-TZ2P) basis set in conjunction with the Becke-Perdew (BP86) functional within generalized gradient approximation (GGA).…”