E₅M₇⁺ (E=C–Pb, M=Li–Cs): A Source of Viable Star‐Shaped Clusters

Abstract

Herein we report the systematic exploration of the potential energy surfaces of a series of clusters with formula E M (E=C-Pb and M=Li-Cs). Fifteen of these combinations adopt a D three-dimensional seven-pointed star-like structure in a singlet state, where M atoms interact electrostatically with the E ring. The determining factors in the relative preference of having the D structure over the most competitive isomer or vice-versa are analyzed. These star-shaped systems satisfy the 4n+2 Hückel's rule and exhibit a strong diatropic (σ and π) response to an external magnetic field.

(Li6Si5)2–5: The Smallest Cluster‐Assembled Materials Based on Aromatic Si56− Rings

“…The presence of both, a significantly diatropic (shielding) region inside the Si 5 6− ring (under an external magnetic field), and 4 n +2 π‐electrons (fulfilling Hückel's rule) undoubtedly allowed us to classify these species as aromatic. Interestingly, the strong electrostatic interaction between the ring and the lithium counterions also contributes to these being the energetically preferred isomers, even in the absence of the Y‐shaped Si 4 unit of the Li 12 Si 7 compound. Taking this background into account, the question arises as to whether Li 7− x Si 5 1− x ( x= 0, 1, 2) clusters could be used to build larger systems, that is, nanomaterials.…”

Si5-pentagonal rings and Y-shaped Si4building blocks in Li32Si18system: similarities with the crystalline Zintl phase Li12Si7

“…In the case of Li 6 Si 5 , we obtain a similar representation to the one previously reported, 52 five lone pairs, one on each Si, five Si-Si σ-bonds plus three delocalized π-bonds connecting the Si 5 ring, the latter consistent with the aromatic character of this cluster. 49,93,94 For the case of Li 10 Si 4 , AdNDP recovers six lone pairs (two on each of the three external silicon). Also, three Si-Si σ-bonds connect the central Si to the external ones.…”

3‐Dmolecular stars with covalent axial bonding

“…Chemists have always been fascinated by molecules with beautiful architectures and unusual bonding, among which the molecular stars, 1–21 especially the five‐point stars, are a charming division of such molecules. Currently, the majority of molecular stars are planar stars featuring the non‐classical planar hyper‐coordination.…”

“…Consequently, a feasible way to retain the delocalized π bond in 3‐D molecular stars is to make the electrostatic interactions as the dominant bonding pattern between axial atoms/groups and equatorial moiety. In fact, in currently known 3‐D molecular stars, the electrostatic interactions are dominant for bonding not only between axial atoms and equatorial framework, but also between peripheral atoms and central polygons within the equatorial framework, as represented by E 5 M 7 + (E = C‐Pb, M = Li‐Cs), 18,19 Li 7 (BH) 5 + , 20 and B 6 Li 8 , 21 and so forth.…”