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Xu S, Wang Q, Rajeshkumar T, Jiang S, Maron L, Xu X. Reductive Dimerization of Alkenes and Allenes Enabled by Photochemically Activated Zinc-Zinc Bonded Compounds. J Am Chem Soc 2024; 146:19590-19598. [PMID: 38957130 DOI: 10.1021/jacs.4c07390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Metal radicals have shown versatile reactivity in modern synthetic chemistry. However, the use of zinc radicals for molecular synthesis has been barely explored. Here, we show that a transient zinc radical can be formed through photoactivation of a zinc-zinc bonded compound, which is able to mediate the selective dimerization of alkenes and allenes. Treatment of dizinc compounds [L2Zn2] [L = CH3C(2,6-iPr2C6H3N)CHC(CH3)(NCH2CH2PR2); R = Ph (LPh) or iPr (LiPr)] with a diverse array of aromatic alkenes under UV irradiation (365 nm) facilely afforded the head-to-head coupling products, i.e., 1,4-dizinciobutanes in high yields. In addition, arylallenes could also be selectively dimerized by the dizinc compound to give 2,5-dizincyl-functionalized 1,5-hexadienes under the same conditions. Control reactions of [LPh2Zn2] in the presence of UV irradiation isolated a zinc phenyl complex and a trimeric zinc phosphide complex resulting from C-P bond cleavage at the tridentate ligand. Reactions of photoactivated dizinc compounds with organic spin traps, i.e., 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and 2,2'-bipyridine (2,2'-bpy), successfully isolated zinc radical trapping products [LZnOTEMP] and [LPhZn(2,2'-bpy)·-], respectively. The profile of alkene dimerization was elucidated by density functional theory calculations, which confirmed that a transient zinc radical [LZn·] was initially generated through homolytic Zn-Zn bond cleavage via photoactivation followed by single-electron transfer and radical dimerization. The unique selectivity of the current reaction was also studied computationally.
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Affiliation(s)
- Shuilian Xu
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Qiujie Wang
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Thayalan Rajeshkumar
- LPCNO, CNRS & INSA, Université Paul Sabatier, 135 Avenue de Rangueil, Toulouse 31077, France
| | - Shengjie Jiang
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Laurent Maron
- LPCNO, CNRS & INSA, Université Paul Sabatier, 135 Avenue de Rangueil, Toulouse 31077, France
| | - Xin Xu
- Key Laboratory of Organic Synthesis of Jiangsu Province, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
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Qu Y, Xi Z, Sun Z, Yang L, Liu R, Dong B, Wu B, Yang XJ. Activation of cyclopentadiene derivatives by an α-diimine-ligated Mg-Mg-bonded compound. Dalton Trans 2024; 53:10065-10069. [PMID: 38847200 DOI: 10.1039/d4dt01038h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2024]
Abstract
Heteroleptic, bimetallic (Mg/K) cyclopentadienyl complexes (2-4) were synthesized by the reaction of the Mg-Mg-bonded compound [K(THF)3]2[LMg-MgL] (1, L = [(2,6-iPr2C6H3)NC(CH3)]22-) with cyclopentadiene derivatives, 6,6-dimethylfulvene, 6-(dimethylamino)fulvene, or 1,2,3,4-tetramethyl-1,3-cyclopentadiene. The reactions proceed through diverse pathways, including hydrogen abstraction, C-C coupling, and dehydrogenation, depending on the property of the polyene substrate, thus providing an access to alkali/alkaline earth metal cyclopentadienyl complexes.
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Affiliation(s)
- Yao Qu
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
| | - Zhixian Xi
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
| | - Zhenzhou Sun
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
| | - Li Yang
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
| | - Rui Liu
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
| | - Ben Dong
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
| | - Biao Wu
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
| | - Xiao-Juan Yang
- Key Laboratory of Medicinal Molecule Science and Pharmaceutics Engineering, Ministry of Industry and Information Technology, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China.
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Evans MJ, Mullins J, Mondal R, Jones C. Reductions of Arenes using a Magnesium-Dinitrogen Complex. Chemistry 2024; 30:e202401005. [PMID: 38622992 DOI: 10.1002/chem.202401005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/15/2024] [Accepted: 04/16/2024] [Indexed: 04/17/2024]
Abstract
In this contribution, we present "Birch-type", and other reductions of simple arenes by the potassium salt of an anionic magnesium dinitrogen complex, [{K(TCHPNON)Mg}2(μ-N2)] (TCHPNON=4,5-bis(2,4,6-tricyclohexylanilido)-2,7-diethyl-9,9-dimethyl-xanthene), which acts as a masked dimagnesium(I) diradical in these reactions. This reagent is non-hazardous, easy-to-handle, and in some cases provides access to 1,4-cyclohexadiene reduction products under relatively mild reaction conditions. This system works effectively to reduce benzene, naphthalene and anthracene through magnesium-bound "Birch-type" reduction intermediates. Cyclohexadiene products can be subsequently released from the magnesium centres by protonolysis with methanol. In contrast, the reduction of substituted arenes is less selective and involves competing reaction pathways. For toluene and 1,3,5-triphenylbenzene, the structural authentication of "Birch-type" reduction intermediates is conclusive, although the formation of corresponding 1,4-cyclohexadiene derivatives was low yielding. Reduction of anisole did not yield an isolable "Birch-type" intermediate, but instead gave a C-O activation product. Treating triphenylphosphine with [{K(TCHPNON)Mg}2(μ-N2)] resulted in the extrusion of both biphenyl and dinitrogen to afford a magnesium(II) phosphanide [{K(TCHPNON)Mg(μ-PPh2)}2]. Reduction of fluorobenzene proceeded via C-F activation of the arene, and isolation of the magnesium(II) fluoride [{K(TCHPNON)Mg(μ-F)}2]. Finally, the two-electron reduction of 1,3,5,7-cyclooctatetraene (COT) with [{K(TCHPNON)Mg}2(μ-N2)] yielded a complex, [{K(TCHPNON)Mg}2(μ-COT)], incorporating the aromatic dianion (COT2-).
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Affiliation(s)
- Matthew J Evans
- School of Chemistry, Monash University, PO Box 23, 3800, Melbourne, Victoria, Australia
| | - Jeremy Mullins
- School of Chemistry, Monash University, PO Box 23, 3800, Melbourne, Victoria, Australia
| | - Rahul Mondal
- School of Chemistry, Monash University, PO Box 23, 3800, Melbourne, Victoria, Australia
| | - Cameron Jones
- School of Chemistry, Monash University, PO Box 23, 3800, Melbourne, Victoria, Australia
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Duneş G, Cordier M, Kahlal S, Pöllnitz A, Saillard JY, Silvestru C, Sarazin Y. C-H bond activation at antimony(III): synthesis and reactivity of Sb(III)-oxyaryl species. Dalton Trans 2024. [PMID: 38868997 DOI: 10.1039/d4dt01400f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
We report on the synthesis, structure and reactivity of [{NCNMe4}Sb(C6H2-tBu2-3,5-O-4)] (3), an organoantimony(III)-oxyaryl species obtained upon Csp2-H bond activation in a phenolate ligand and stabilised by the monoanionic pincer {NCNMe4}-. The mechanism leading to the formation of 3 is highly sensitive to steric considerations. It was probed experimentally and by DFT calculations, and a number of intermediates and related complexes were identified. All data agree with successive heterolytic bond cleaving and bond forming processes involving charged species, rather than a pathway involving free radicals as previously exemplified with congeneric bismuth species. The nucleophilic behaviour of the oxyaryl ligand in 3, a complex that features both zwitterionic and quinoidal attributes, was illustrated in derivatisation reactions. In particular, insertion of CS2 in the Sb-Coxyaryl bond generates [{NCNMe4}Sb(S2C-C6H2-tBu2-3,5-O-4)].
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Affiliation(s)
- Gabriel Duneş
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Campus de Beaulieu, 35042 Rennes, Cedex, France.
- Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, 11 Arany Janos, 400028 Cluj-Napoca, Romania.
| | - Marie Cordier
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Campus de Beaulieu, 35042 Rennes, Cedex, France.
| | - Samia Kahlal
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Campus de Beaulieu, 35042 Rennes, Cedex, France.
| | - Alpar Pöllnitz
- Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, 11 Arany Janos, 400028 Cluj-Napoca, Romania.
| | - Jean-Yves Saillard
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Campus de Beaulieu, 35042 Rennes, Cedex, France.
| | - Cristian Silvestru
- Department of Chemistry, Supramolecular Organic and Organometallic Chemistry Centre (SOOMCC), Faculty of Chemistry and Chemical Engineering, Babeş-Bolyai University, 11 Arany Janos, 400028 Cluj-Napoca, Romania.
| | - Yann Sarazin
- Université de Rennes, CNRS, Institut des Sciences Chimiques de Rennes, UMR 6226, Campus de Beaulieu, 35042 Rennes, Cedex, France.
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Evans MJ, Jones C. Low oxidation state and hydrido group 2 complexes: synthesis and applications in the activation of gaseous substrates. Chem Soc Rev 2024; 53:5054-5082. [PMID: 38595211 DOI: 10.1039/d4cs00097h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
Numerous industrial processes utilise gaseous chemical feedstocks to produce useful chemical products. Atmospheric and other small molecule gases, including anthropogenic waste products (e.g. carbon dioxide), can be viewed as sustainable building blocks to access value-added chemical commodities and materials. While transition metal complexes have been well documented in the reduction and transformation of these substrates, molecular complexes of the terrestrially abundant alkaline earth metals have also demonstrated promise with remarkable reactivity reported towards an array of industrially relevant gases over the past two decades. This review covers low oxidation state and hydrido group 2 complexes and their role in the reduction and transformation of a selection of important gaseous substrates towards value-added chemical products.
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Affiliation(s)
- Matthew J Evans
- School of Chemistry, Monash University, PO Box 23, Melbourne, Victoria, 3800, Australia.
| | - Cameron Jones
- School of Chemistry, Monash University, PO Box 23, Melbourne, Victoria, 3800, Australia.
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Liu HY, Neale SE, Hill MS, Mahon MF, McMullin CL, Richards E. [{SiN Dipp}MgNa] 2: A Potent Molecular Reducing Agent. Organometallics 2024; 43:879-888. [PMID: 38665773 PMCID: PMC11041119 DOI: 10.1021/acs.organomet.4c00076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/17/2024] [Accepted: 03/25/2024] [Indexed: 04/28/2024]
Abstract
The bimetallic species, [{SiNDipp}MgNa]2 [{SiNDipp} = {CH2SiMe2N(Dipp)}2; (Dipp = 2,6-i-Pr2C6H3)], is shown to be a potent reducing agent, able to effect one- or two-electron reduction of either dioxygen, TEMPO, anthracene, benzophenone, or diphenylacetylene. In most cases, the bimetallic reaction products imply that the dissimilar alkaline metal centers react with a level of cooperativity. EPR analysis of the benzophenone-derived reaction and the concurrent isolation of [{SiNDipp}Mg(OCPh2)2], however, illustrate that treatment with such reducible, but O-basic, species can also result in reactivity in which the metals provide independent reaction products. The notable E-stereochemistry of the diphenylacetylene reduction product prompted a computational investigation of the PhC≡CPh addition. This analysis invokes a series of elementary steps that necessitate ring-opening via Mg+ → Na+ amido group migration of the SiNDipp ligand, providing insight into the previously observed lability of the bidentate dianion and its consequent proclivity toward macrocyclization.
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Affiliation(s)
- Han-Ying Liu
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Samuel E. Neale
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Michael S. Hill
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Mary F. Mahon
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Claire L. McMullin
- Department
of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K.
| | - Emma Richards
- School
of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
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Nguyen DT, Helling C, Evans MJ, Jones C. Enforcing Metal-Arene Interactions in Bulky p-Terphenyl Bis(anilide) Complexes of Group 2 Metals (Be-Ba): Potential Precursors for Low-Oxidation-State Alkaline Earth Metal Systems. Inorg Chem 2024; 63:5718-5726. [PMID: 38471088 DOI: 10.1021/acs.inorgchem.4c00207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/14/2024]
Abstract
An extremely bulky p-terphenyl bis(aniline), p-C6H4{C6H4[N(H)TCHP]-2}2 (TCHP = 2,4,6-tricyclohexylphenyl) TCHPTerphH2, has been developed. Deprotonation of a less bulky analogue, DipTerphH2 (Dip = 2,6-diisopropylphenyl), with BePh2 affords the bimetallic system, [(BePh)2(μ-DipTerph)] 1. Treating either TCHPTerphH2 or DipTerphH2 with Mg{CH2(SiMe3)}2 gives the monomeric bis(anilide) complexes [Mg(ArTerph)] (Ar = Dip 2, TCHP 3) which display rare examples of η6-arene coordination to the metal center. Treating 2 with THF leads to partial dissociation of the Mg···arene interaction and formation of [Mg(DipTerph)(THF)] 4. Reactions of the bis(aniline)s with the group 2 metal amides [M{N(SiMe3)2}2] afford dimeric, structurally analogous compounds [{M(ArTerph)}2] (Ar = Dip, M = Ca 5, Sr 6, Ba 7; Ar = TCHP, M = Ca 8, Sr 9, Ba 10) which display intermolecular M···arene interactions in the solid state. Computational studies have shown that the intramolecular M···η6-arene interactions in models of the ether-free metal bis(anilide) compounds are largely electrostatic in nature. Reductions of these compounds with alkali metals led to mixtures of unidentified products.
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Affiliation(s)
- Dat T Nguyen
- School of Chemistry, Monash University, P.O. Box 23, Melbourne 3800, Victoria, Australia
| | - Christoph Helling
- School of Chemistry, Monash University, P.O. Box 23, Melbourne 3800, Victoria, Australia
| | - Matthew J Evans
- School of Chemistry, Monash University, P.O. Box 23, Melbourne 3800, Victoria, Australia
| | - Cameron Jones
- School of Chemistry, Monash University, P.O. Box 23, Melbourne 3800, Victoria, Australia
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Mondal R, Evans MJ, Nguyen DT, Rajeshkumar T, Maron L, Jones C. Steric control of Mg-Mg bond formation vs. N 2 activation in the reduction of bulky magnesium diamide complexes. Chem Commun (Camb) 2024; 60:1016-1019. [PMID: 38170497 DOI: 10.1039/d3cc05787a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Reduction of the magnesium(II) diamide [Mg(TripNON)] (TripNON = 4,5-bis(2,4,6-triisopropylanilido)-2,7-diethyl-9,9-dimethyl-xanthene) with 5% w/w K/KI leads to a good yield of a dianionic dimagnesium(I) species, as its potassium salt, [{K(TripNON)Mg}2]. An X-ray crystallographic analysis shows the molecule to contain a very long Mg-Mg bond (3.137(2) Å). The formation of [{K(TripNON)Mg}2] contrasts with a previously reported reduction of a magnesium(II) complex incorporating a bulkier diamide ligand, which instead afforded a magnesium-dinitrogen complex. In the current study, [{K(TripNON)Mg}2] has been shown to be a viable reagent for the reductive activation of CO, H2 and N2O.
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Affiliation(s)
- Rahul Mondal
- School of Chemistry, Monash University, PO Box 23, Melbourne, VIC, 3800, Australia
| | - Matthew J Evans
- School of Chemistry, Monash University, PO Box 23, Melbourne, VIC, 3800, Australia
| | - Dat T Nguyen
- School of Chemistry, Monash University, PO Box 23, Melbourne, VIC, 3800, Australia
| | - Thayalan Rajeshkumar
- Université de Toulouse et CNRS, INSA, UPS, UMR5215, LPCNO, 135 Avenue de Rangueil, Toulouse 31077, France.
| | - Laurent Maron
- Université de Toulouse et CNRS, INSA, UPS, UMR5215, LPCNO, 135 Avenue de Rangueil, Toulouse 31077, France.
| | - Cameron Jones
- School of Chemistry, Monash University, PO Box 23, Melbourne, VIC, 3800, Australia
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