Reduction of Carbon Dioxide with Amalgams

Rm, Miller; Knorr, Harald; Eichel, H. J.; Meyer, C. M.; Tanner, Howard A.

doi:10.1021/jo01054a510

Cited by 7 publications

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“…To determine if the LnZ 3 /M and LnZ 2 Z‘/M reduction systems would lead to unusual chemistry with substrates other than dinitrogen, reactions with CO 2 were examined. Carbon dioxide is a more complicated substrate than dinitrogen for this system, since there is independently reported chemistry between CO 2 and alkali metals. − For example, alkali and alkaline earth metal amalgams react with CO 2 at temperatures from 25 to 180 °C to make a variety of products including carbonates and oxalates.…”

Section: Introductionmentioning

confidence: 99%

Facile Insertion of CO₂ into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C₅Me₄RCO₂)^- Carboxylate Ligands (R = H, Me)

et al. 2007

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Recent efforts to extend the reduction chemistry of LnZ 3 /M and LnZ 2 Z′/M (Ln ) lanthanide; Z ) C 5 Me 5 , C 5 Me 4 H; Z′ ) BPh 4 , Cl; M ) alkali metal) to substrates beyond N 2 have identified unexpectedly facile insertion of CO 2 into lanthanide cyclopentadienyl linkages to make carboxylate ligands. The insertion was initially identified in [(C 5 Me 4 H)La(THF)] 3 (µ-η 1 :η 1 -O 2 CC 5 Me 4 H) 3 (µ 3 -η 2 :η 2 :η 2 -CO 3 )(µ 3 -Cl), 1, a product of a (C 5 Me 4 H) 3 La/Na/CO 2 reaction in the presence of chloride. In this case, both insertion and reduction of CO 2 to carbonate was observed. A [(C 5 Me 5 ) 2 La][(µ-Ph) 2 BPh 2 ]/KC 8 /CO 2 reaction also provided a CO 2 insertion product, [(C 5 Me 5 )La(µ-η 1 :η 1 -O 2 CC 5 Me 5 )(µ-η 1 :η 2 -O 2 CC 5 Me 5 )] 2 , 2, but in this case a CO 2 reduction product was not identified. CO 2 insertion also occurs in the absence of an alkali metal. Hence, the (C 5 -Me 4 H) 3 Ln complexes (Ln ) La, Nd, Sm, Gd) react with CO 2 to form mixtures of tetramethylcyclopentadienyl carboxylate products. In the La complex, single crystals of {[(C 5 Me 4 H) 2 La](µ-η 1 :η 1 -O 2 CC 5 -Me 4 H)} 2 , 3, could be isolated and structurally characterized. Crystallographic characterization of a rare example of a tetramethylcyclopentadienyl lanthanide ate salt, [(µ-C 5 Me 4 H)(C 5 Me 4 H)LaCl(µ-Cl)K(18crown-6)] n , 4, was also obtained as part of this study, and it was found to have a chain structure in the solid state involving bridging methyl groups as well as bridging chloride ligands.

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Section: Introductionmentioning

confidence: 99%

Facile Insertion of CO₂ into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C₅Me₄RCO₂)^- Carboxylate Ligands (R = H, Me)

et al. 2007

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Incorporation and deoxygenation of carbon dioxide: A metal‐assisted facile conversion of carbon dioxide and primary amines to isocyanates

1988

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Metal N-alkylcarbamato complexes [M(O,CNHR).] (M = Na, n = 1; M = Mn, Co, n = 2) were prepared by treating C02 with a primary m i n e RNH2 (R = Ph, Cy, Pr) and various complex precursors. For M = Mn or C o and R = Cy, MCI? can be used as starting material. These complexes were readily decomposed by acyl halides R'COCI (R' = Ph, Me), and two reaction pathways were observed. One led to decarboxylation and formation of amides RNHC(O)R', while the other afforded isocyanate RNCO and carboxylic acid (M = Na) or carboxylic anhydride (M. = Mn, Co). Analysis of the reaction products showed that the metal plays a major r81e in the formation of the isocyanate, intercepting one of the reaction products. A mechanistic rationalization is proposed.The'effective utilization of the carbon dioxide molecule may follow two different routes, i. e. reduction and incorporation". Reduction of CO? implies its convcrsion to other C, molecules (such as CO, HCOOH, CHIOH or CH.,), by reaction with high-energy reductants such as metal hydrides" or hydrogen ' I; or by reduction with external energy sources such as electrochemical potential4' or light 'I, usually in the presence of transition metal complexes as electron transfer agcnts. Most frequently the products of both electrochemical or light-driven reductions arc formates and/or CO, and a common mechanistic feature is the p r~p o s e d~"~~~' ;~"~' formation of an intermediate MCOOH. This requires the formation of a metalcarbon bond between an electron-rich metal centre and COz, reminiscent of the coordination of carbon dioxide to nucleophilic metal complexes?Incorporation of carbon dioxidc, on the other hand, deals with the formation of C -C02, N -C02, or 0-COz bonds. These reactions arc consistent with the ready reactivity of C 0 2 towards nucleophiles, and in some cases can be used in catalytic proce~ses'.~.~'. As the formation of a carbon-element bond betwcen the carbon atom of C 0 2 and the substrate is required, it is not surprising that this chemistry does not make much use of the coordination chemistry of CO?'. The use of metal systems may nevertheless constitute an important stage in the stoichiometric COz incorporation processes. The formation of a metal -oxygen bond is, for example, involved in the stoichiometric C-C coupling of CO? with olefinslO' and with organometallic compounds 'I).In N -CO? adducts, the presence of a metal may help to stabilize the carbamato anion obtained from the. interaction of a secondary amine with carbon dioxide12"', and this led us to the synthesis and characterization of transition metal N.N-dialkylcarbamato complexes of the general formula [M (02CNRz) preparation of urethanes from C02"', and we have shown that metal-assisted electrophilic reactions may be performed on the oxygen atoms of the C 0 2 moiety of metal carbamatesi4', thus providing, for example, a facile synthesis of mixed carbamato-carboxylato anhydrides [see equation (l) Cu(1l) Examination of reaction (1) suggested that monosubstituted N-alkylcarbamates could be precursors of the un...

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Fundamental physical properties and structure of carbon dioxide and its derivatives

Станкевич¹,

Lysyak²,

Александров³

et al. 1979

J Struct Chem

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Reduction of Carbon Dioxide with Amalgams

Cited by 7 publications

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Facile Insertion of CO₂ into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C₅Me₄RCO₂)^- Carboxylate Ligands (R = H, Me)

Facile Insertion of CO₂ into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C₅Me₄RCO₂)^- Carboxylate Ligands (R = H, Me)

Incorporation and deoxygenation of carbon dioxide: A metal‐assisted facile conversion of carbon dioxide and primary amines to isocyanates

Fundamental physical properties and structure of carbon dioxide and its derivatives

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Reduction of Carbon Dioxide with Amalgams

Cited by 7 publications

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Facile Insertion of CO2 into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C5Me4RCO2)- Carboxylate Ligands (R = H, Me)

Facile Insertion of CO2 into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C5Me4RCO2)- Carboxylate Ligands (R = H, Me)

Incorporation and deoxygenation of carbon dioxide: A metal‐assisted facile conversion of carbon dioxide and primary amines to isocyanates

Fundamental physical properties and structure of carbon dioxide and its derivatives

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Facile Insertion of CO₂ into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C₅Me₄RCO₂)^- Carboxylate Ligands (R = H, Me)

Facile Insertion of CO₂ into Tetra- and Pentamethylcyclopentadienyl Lanthanide Moieties To Form (C₅Me₄RCO₂)^- Carboxylate Ligands (R = H, Me)