Alkaline‐Earth‐Promoted CO Homologation and Reductive Catalysis

Anker, Mathew D.; Hill, Michael S.; Lowe, John P.; Mahon, Mary F.

doi:10.1002/anie.201505851

Cited by 82 publications

(83 citation statements)

References 20 publications

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“…[9,10] Conscious efforts have been made to obtain aw ide variety of composition and nuclearity ranging from mononuclear terminal hydrides [10e,g,-j,u,w] to clusters. [10t] Apart from being models for hydrogen-storage materials,s ome of the hydrides have been identified as key intermediates in catalytic reactions,s uch as hydroboration, [10m, 11] hydrosilylation, [12] CO homologation, [12c,d] and dehydrogenative coupling between amine and hydroborane, [13] amine and hydrosilane, [14] and TEMPO and hydrosilane. [10t] Apart from being models for hydrogen-storage materials,s ome of the hydrides have been identified as key intermediates in catalytic reactions,s uch as hydroboration, [10m, 11] hydrosilylation, [12] CO homologation, [12c,d] and dehydrogenative coupling between amine and hydroborane, [13] amine and hydrosilane, [14] and TEMPO and hydrosilane.…”

Section: Scopementioning

confidence: 99%

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Molecular Magnesium Hydrides

Mukherjee

Okuda

2017

Angew Chem Int Ed

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Solid magnesium hydride [MgH ] has been pursued as a potential hydrogen-storage material. Organic chemists were rather interested in soluble magnesium hydride reagents from mid-20th century. It was only in the last two decades that molecular magnesium hydride chemistry received a major boost from organometallic chemists with a series of structurally well-characterized examples that continues to build a whole new class of compounds. More than 40 such species have been isolated, ranging from mononuclear terminal hydrides to large hydride clusters with more than 10 magnesium atoms. They provide not only insights into the structure and bonding of Mg-H motifs, but also serve as models for hydrogen-storage materials. Some of them are also recognized to participate in catalytic transformations, such as hydroelementation. Herein, an overview of these molecular magnesium hydrides is given, focusing on their synthesis and structural characterization.

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Section: Scopementioning

confidence: 99%

“…With as lightly larger bite angle and smaller ring-size, [PN5] À led to amagnesium hydride cluster with asignificantly different structure.Independent of temperature,the reaction with phenylsilane in benzene gave the dodeca-nuclear [(PN5) 12 …”

Section: Tris(pyrazolyl)methanidementioning

confidence: 99%

Molecular Magnesium Hydrides

Mukherjee

Okuda

2017

Angew Chem Int Ed

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“…ORTEP representation of compound 1 (25 %p robability ellipsoids). [9] Iso-propyl methyl groups and hydrogen atoms except those attached to C30 and C31 are removed for clarity. (6), O1-Mg1-N1 120.14(7), O1-Mg1-N2 118.32 (7), O2-Mg2-N3 133.09 (7), O2-Mg2-N4 128.81 (7), N3-Mg2-N4 97.50(6).…”

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confidence: 99%

Alkaline‐Earth‐Promoted CO Homologation and Reductive Catalysis

et al. 2015

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Reaction between a b-diketiminato magnesium hydride and carbon monoxide results in the isolation of adimeric cis-enediolate species through the reductive coupling of two CO molecules.Under catalytic conditions with PhSiH 3 , an observable magnesium formyl species may be intercepted for the mild reductive cleavage of the CO triple bond.The deoxygenative conversion of carbon monoxide to hydrocarbon fuels and lower oxygenates is typically achieved through heterogeneous catalytic methods.[1] Although Fischer-Tropsch (F-T) chemistry and related processes have been successfully implemented for some eighty years to produce aS chultz-Flory distribution of hydrocarbons,o nly limited success has been achieved with well-defined homogeneous systems,t ypically at CO pressures in excess of 1000 atm.[2] More recent activity has targeted the synthesis of putative F-T intermediates including,and most pertinent to the current work, enediolates such as the zirconium and cerium species I-III,which were prepared through treatment of the relevant metal hydride with CO.[3] Our own research efforts have focused on the development of ah omogeneous catalytic chemistry for complexes derived from the inexpensive and environmentally benign alkaline-earth elements, [4] in particular magnesium and calcium;r espectively the eighth and fifth most abundant elements in the lithosphere.I nt his contribution we demonstrate that similar CO homologation reactivity may be achieved through exposure of the bdiketiminato magnesium hydride (IV) [5] to one atmosphere of CO and that this and other alkaline earth species enable the highly selective catalytic reduction of the carbon monoxide molecule under similarly mild reaction conditions.Compound IV reacted under one atmosphere of CO at room temperature to provide as ingle new species (1) 12 CO resulted in no simplification of the AA'XX' spin system even at elevated temperatures indicating that the formation of compound 1 is irreversible.T hese spectral data are closely comparable to those reported for compounds I-III and are thus similarly indicative of the reductive coupling of two molecules of CO to form ad inuclear magnesium enediolate species [Eq. (1)]. [3] These deductions were confirmed through as ubsequent X-ray structural analysis,the results of which are illustrated in Figure 1, performed on as elected single crystal of compound 1 grown from as aturated n-pentane solution. While the C30-C31 distance [1.327(3) ] is clearly indicative of the formation of aC =Cdouble bond and a cis-enediolate similar to that observed in both compounds II and III,the ligand does not display ad irectly analogous symmetrical bridging disposition. Rather, the planar cis-enediolate adopts an asymmetric bridging mode in which one four-coordinate pseudo-tetrahedral magnesium (Mg1) center is bound through chelation of both O1 [Mg1-O1 1.92(1) ] and O2 [Mg1-O2 2.01 (1) ]. This latter bond is slightly elongated as O2 is also bound to the further trigonal Mg2 center [Mg2-O2 1.88(1) ].V ariable-temperature 1 HNMR st...

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“…[26] This reaction can be considered as hydrosilylation, although the final product is methyl phenyl silane and the corresponding disiloxane, andt he CÀOb ondo fC Ow as cleaved (Scheme 15). [26] This reaction can be considered as hydrosilylation, although the final product is methyl phenyl silane and the corresponding disiloxane, andt he CÀOb ondo fC Ow as cleaved (Scheme 15).…”

Section: Hydrosilylationmentioning

confidence: 99%

“…[23] Scheme13. [26] ChemCatChem 2016, 8, [10][11][12][13][14][15][16][17][18][19][20] www.chemcatchem.org [24] Scheme14.…”

Section: Hydrosilylationunclassified

Recent Developments in Homogeneous Organomagnesium Catalysis

et al. 2015

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Stoichiometric organomagnesium chemistry has continually progressed since its initiation by Victor Grignard over one century ago. Other than acting as a Lewis acid, however, homogeneous magnesium catalysis is a rare topic in the literature. Magnesium catalysts that govern reactions within the coordination sphere of magnesium have only recently begun to appear. This Concept covers recent progress in this young but potentially powerful new chapter of magnesium chemistry.

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Alkaline‐Earth‐Promoted CO Homologation and Reductive Catalysis

Cited by 82 publications

References 20 publications

Molecular Magnesium Hydrides

Molecular Magnesium Hydrides

Alkaline‐Earth‐Promoted CO Homologation and Reductive Catalysis

Recent Developments in Homogeneous Organomagnesium Catalysis

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