Dodeca(benzyloxy)dodecaboran B12(OCH2Ph)12: ein stabileshypercloso-B12H12-Derivat

Abstract

Durch Per‐O‐benzylierung von [closo‐B12(OH)12]2− 12− mit Benzylchlorid und anschließende Oxidation mit zwei Äquivalenten FeIII gelang die Synthese von 2, dem Per(benzyloxy)‐Derivat von hypercloso‐B12H12 (siehe Schema). Verbindung 2 wurde 11B‐NMR‐ und elektronenspektroskopisch, massenspektrometrisch, cyclovoltammetrisch und röntgenographisch charakterisiert.

Two-Electron-Transfer Redox Systems, Part 7: Two-Step Electrochemical Oxidation of the Boron Subhalide Cluster Dianions (X = Cl, Br, I)

“…Various reports of electrochemical redox transformations between closo -dianionic and hypercloso -neutral boron subhalide clusters with n = 8−11 consistently show that the two electrons are transferred in separate one-electron steps at distinguishable redox (or formal) potentials E 0 . ,,,, The E 0 of the two steps are separated by several hundred mV, a result which is also found for the benzyloxy−B 12 cluster mentioned above . This “normal” potential ordering is usually an indication that no appreciable reorganization of the molecular structure is involved in the redox reactions …”

“…Although they are exceptions to Wade's rules, such hypercloso compounds have been isolated in the boron subhalide series, e.g., for X = Cl and n = 8 and 9. , Their stability is explained by a combination of the π-donor properties of the halogen atoms and steric effects . Similar stabilization was observed for B 12 (OCH 2 Ph) 12 …”

“…10 Similar stabilization was observed for B 12 (OCH 2 Ph) 12 . 11 Various reports of electrochemical redox transformations between closo-dianionic and hypercloso-neutral boron subhalide clusters with n ) 8-11 consistently show that the two electrons are transferred in separate one-electron steps at distinguishable redox (or formal) potentials E 0 . 6,7,9,12,13 The E 0 of the two steps are separated by several hundred mV, a result which is also found for the benzyloxy-B 12 cluster mentioned above.…”

“…6,7,9,12,13 The E 0 of the two steps are separated by several hundred mV, a result which is also found for the benzyloxy-B 12 cluster mentioned above. 11 This "normal" potential ordering is usually an indication that no appreciable reorganization of the molecular structure is involved in the redox reactions. 14 Changes in bond lengths and angles between the clusters B 9 Br 9 0/•-/2have been investigated in detail.…”

An Improved Method for the Synthesis of [closo-B12(OH)12]-2

“…12 These so-called camouflaged polyhedral borane derivatives 13 serve as cores for the synthesis of dendrimer-like derivatives known as closomers. 14 Very recently it has been demonstrated that the spherical sheath of hydroxyl groups in 4 can be fully derivatized affording closomeric dodecaesters 14,15 and dodecaethers, 16,17 respectively. Furthermore, dodecaborates bearing twelve organic linkers with terminal functionality were synthesized 18 for biomedical applications.…”