Stepwise reduction of a base-stabilised ferrocenyl aluminium(iii) dihalide for the synthesis of structurally-diverse dialane species

Abstract

We report the reduction of bulky ferrocenyl-based NHC-stabilised aluminium(III) diiodide [Fc*(NHC)AlI2] (Fc* = 2,5-bis(3,5-di-tert-butylphenyl)-1-ferrocenyl) in different hydrocarbon solvents (hexane, benzene, toluene, and p-xylene), which results in different outcomes. Reduction in...

Evidence of AlIIRadical Addition to Benzene

“…In confirmation of the 1 H NMR data, the 13 C NMR spectrum shows two new signals at chemical shifts of 124.6 and 29.9 ppm. These NMR spectroscopic data compare favorably with the reported quinoid type benzene moiety suggesting a Birch‐type reduction product of benzene [14a, 19, 20] …”

“…Notably, the isolobal Mg compound can also undergo a Birch‐type benzene reduction, when the dimerization of the intermediate Mg I radical is prevented by a super bulky spectator ligand ((HC{C(Me)N[2,6‐(3‐pentyl)‐phenyl]} 2 )) and a coordinating species, TMEDA (N,N,N′,N′‐tetramethylethylenediamine) [19] . In the course of the development of this work, the group of Braunschweig reported a similar outcome, in which the aluminum center is coordinated to an N ‐heterocyclic carbene (NHC) and stabilized by a redox‐active ferrocenyl substituent [20] . Although it was not possible to isolate or characterize a radical addition to arenes, the authors proposed a plausible radical‐based mechanism.…”

Al–Sc Bonded Complexes: Synthesis, Structure, and Reaction with Benzene in the Presence of Alkyl Halide

“…Distinguished C–C and CC bonds in the central cyclohexadiene ring in 8 demonstrated the dearomatization of the benzene ring during the reaction (Figure ). Similar 1,4-dialuminated cyclohexadiene structures were reported by the reaction of benzene with a transient AlAl bonded compound or by the reduction of NHC-coordinated (ferrocenyl)Al diiodide . The 1 H NMR spectrum of 8 in THF- d 8 exhibits the magnetic inequivalence of geminal protons of three CH 2 groups, indicating that Al–O and Al–C bonds are not cleaved in solution.…”

“…Similar 1,4-dialuminated cyclohexadiene structures were reported by the reaction of benzene with a transient Al�Al bonded compound 18 or by the reduction of NHC-coordinated (ferrocenyl)Al diiodide. 19 The 1 H NMR spectrum of 8 in THF-d 8 exhibits the magnetic inequivalence of geminal protons of three CH 2 groups, indicating that Al−O and Al−C bonds are not cleaved in solution. The reaction of 6 with other alkyl bromides, such as PhCH 2 Br, (p-tol) 2 CHBr, bromocyclohexane, 1-bromoadamantane, and n BuBr, also produced 8, as judged by NMR spectroscopy (37−52%, see the Supporting Information).…”

Structure and Reactivity of [Ru–Al] and [Ru–Sn] Heterobimetallic PPh3-Based Complexes

“…In contrast to the well-known metalation of NHCs bearing N-aryl or bulky N-alkyl substituents, 37 C–H activation of N-methylated carbenes is restricted to a very small number of examples, 38 most likely because of the severe structural constraints imposed by forming a four-membered ring metalacycle. These structural impositions are apparent in the X-ray structure of 11 ( Figure 3 ), which shows a dramatically tilted carbene ring with very different N(1)–C(2)–Ru(1) and N(2)–C(2)–Ru(1) angles (99.3(2)° and 156.1(3)° respectively, Δ = 56.8°).…”