Synthesis and Structure of a Carbamato‐bridgded Digallyl‐ferrocenophane – Fixation of Carbon Dioxide with Aminogallanes

Abstract

By reaction of tmp2GaCl (tmp = 2,2,6,6‐tetramethylpiperidino) (1) with dilithioferrocene the 1,1′‐digallylferrocene [{Fe(η5‐C5H4)2}(tmp2Ga)2] (2) was prepared. 2 reacted with CO2 to afford the ferrocenophane [Fe{η5‐C5H4‐Ga(O2Ctmp)(μ2‐O2Ctmp)}2] (3). Here, an eight‐membered Ga(OCO)2Ga‐Ring is the bridge in the ferrocenophane structure. The gallium carbamates [Me2GaO2Ctmp]2 (5), and tmp2Ga(η2‐O2Ctmp) (7) show structural features embedded in 3. The compounds were fully characterized by NMR, cyclovoltammetry and single crystal X‐ray structure analysis.

Lithium and aluminium carbamato derivatives of the utility amide 2,2,6,6-tetramethylpiperidide

“…Indeed, CO 2 insertion to produce carbamates is the current synthetic route of choice given that the original method involved both the use of highly toxic phosgene and the production of HCl as a by-product. Katritzky has published a series of papers using CO 2 as a reagent for simultaneous protection of nucleophilic centres and the activation of alternative locations to nucleophilic attack, 33 Given the structural diversity of alkali-metal amides (vide supra) we set our sights on addressing the paucity of alkalimetal carbamates based on utility amides. Due to our burgeoning interest in the chemistry of diisobutyl aluminium TMP we also studied its carbamato derivative, both via insertion of CO 2 into the Al-N bond of i Bu 2 AlTMP and also by using the lithium TMP carbamate as a ligand transfer agent and report our findings herein.…”

“…This reversal was witnessed previously in Linti's gallium carbamate. 33 All the carbon centres are accounted for in the 13 C NMR spectrum, with the most significant being that in the CO 2 …”

“…Such a route has previously been employed by Linti to give a gallium carbamate 33 but to the best of our knowledge has never been used in the synthesis of an aluminium derivative. The two reagents were allowed to stir overnight in hexane before precipitated LiCl was removed via filtration.…”

Recent Advances in the Chemistry of Metal Carbamates

“…The scenario changed over the last 15 years, as several carbamato complexes obtained by this methodology were reported, and especially organometallic species. These include late d-block metals such as iridium [190,191], nickel [192][193][194][195][196][197], palladium [198,199], gold [200] and zinc [201][202][203][204], f-block metals cerium [134] and uranium [205][206][207][208][209] and p-block metals tin [210] and gallium [211,212]. Furthermore, in situ-formed amide complex of Zn(II) and alkyl-amide of Mg(II) were mixed under carbon dioxide atmosphere to afford a heterobimetallic Zn/Mg alkyl-carbamato derivative [213].…”

Carbon, silicon, germanium, tin and lead

“…The fixation of carbon dioxide remains a popular and competitive area of research driven by the dual goals of finding ways to eliminate excess carbon dioxide from the atmosphere and the commercial possibilities of this abundant and cheap C1 feedstock. This year, new stoichiometric reagents that can capture gaseous carbon dioxide include the hypervalent bismuth compound 1 which captures carbon dioxide from the air to make a bridging carbonate (Scheme 1), 14 dimethyl (2,2,4,4-tetramethylpiperidyl)gallium, which captures two equivalents of carbon dioxide 15 and the copper(I) stannyl 2 that fixes carbon dioxide with the elimination of diphenylstannane (Scheme 2). 16 Nickel complexes of tridentate Schiff-base ligands fix carbon dioxide to make a triangulo trimeric cluster with a triply bridging carbonate.…”