Condensed Two- and Three-Dimensional Aromatic Systems:  A Theoretical Study on the Relative Stabilities of Isomers of CB₁₉H₁₆⁺, B₂₀H₁₅Cl, and B₂₀H₁₄Cl₂ and Comparison to B₁₂H₁₀Cl₂^2-, C₆H₄Cl₂, C₁₀H₇Cl, and C₁₀H₆Cl₂

Abstract

DFT studies (B3LYP/6-31G) on mono- and dichloro derivatives of benzene, naphthalene, B12H12(2-), four-atom-sharing condensed systems B20H16, and monocarborane isomers of B20H16 are used to compare the variation of relative stability and aromaticity between condensed aromatics. The trends in the variation of the relative energies and aromaticity in these two- and three-dimensional systems are similar. Aromaticity, estimated by NICS values, does not change considerably with condensation or substitution. The minor variation in the relative energies of the isomers of chloro derivatives is explained by the topological charge stabilization rule of Gimarc. The compatibility of the cap and ring orbitals decides the relative stability of CB19H16+.

Hypercarbons in polyhedral structures

“…We have studied recently the energetics of the isomers of CB 19 H 16 + . 40 There are four possible isomers viz. Condensation of 9 by edge sharing gives 10.…”

Boron

“…16 DFT studies have been used to compare the relative stabilities and aromaticity of the mono-and dichloro-derivatives of benzene, naphthalene, [B 12 H 12 ] 2À , B 20 H 16 and monocarborane isomers of B 20 H 16 . 17 The molecular structure and the mechanism of formation of the zwitterionic phosphonium borane cluster, [B 12 H 11 (PPh 3 )] À , formed by the reaction of [B 12 H 11 I] 2À with Pd(PPh 3 ) 4 in the presence of Na 2 CO 3 in THF, has been published. 18 Hawthorne and co-workers have developed synthetic procedures for the alkylation of closo-[B 12 (OH) 12 ] 2À .…”

“…DFT calculations have been used to interpret this trend. 119 Dinuclear and trinuclear ferrocene complexes, [ 120 The pentafluorophenyl esters of bis(pentafluorophenyl)borinic acid, (C 6 F 5 ) 2 BOC 6 F 5 (16), pentafluorophenylboronic acid, C 6 F 5 B(OC 6 F 5 ) 2 (17), and boric acid, B(OC 6 F 5 ) 3 (18), have been prepared and characterised by multinuclear NMR and X-ray analysis. The Lewis acidity of all three esters have been compared with B(C 6 F 5 ) 3 , using various Lewis bases.…”

Biicosahedral metallaboranes: aromaticity in metal derivatives of three-dimensional analogues of naphthalene

“…Previous theoretical studies by Jemmis and co-workers have focused on other condensed polyhedral borane derivatives. 15,16 Simple theoretical approaches have been developed to relate the number of skeletal electrons in boron polyhedra to the most stable structures. For the most spherical deltahedra, including the icosahedron, the closed shell n-vertex structures by the Wade-Mingos rules, [17][18][19] This paper describes an initial exploration of possible simple biicosahedral metallaborane structures using the following systems:…”