Imperial College London

Dr Mark R. Crimmin

Faculty of Natural SciencesDepartment of Chemistry

Professor of Organometallic Chemistry
 
 
 
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Contact

 

+44 (0)20 7594 2846m.crimmin Website

 
 
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Location

 

501NMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

107 results found

Crimmin MR, 2021, Benzene rings reach their breaking point, NATURE, Vol: 597, Pages: 33-34, ISSN: 0028-0836

Journal article

Sheldon DJ, Crimmin MR, 2021, Complete deconstruction of SF6 by an aluminium(i) compound, CHEMICAL COMMUNICATIONS, Vol: 57, Pages: 7096-7099, ISSN: 1359-7345

Journal article

Phillips NA, Kong RY, White AJP, Crimmin MRet al., 2021, Group 11 Borataalkene Complexes: Models for Alkene Activation, Angewandte Chemie, Vol: 133, Pages: 12120-12126, ISSN: 0044-8249

Journal article

Phillips N, Kong R, White A, Crimmin MRet al., 2021, Slippage between η2 and η1 coordination in Group 11 borataalkene complexes: models for alkene activation, Angewandte Chemie International Edition, Vol: 60, Pages: 12013-12019, ISSN: 1433-7851

A series of linear late transition metal (M = Cu, Ag, Au and Zn) complexes featuring a side-on [B=C] - containing ligand have been isolated and characterised. The [B=C] - moiety is isoelectronic with the C=C system of an alkene. Comparison across the series shows that in the solid-state, deviation between the η 2 and η 1 coordination mode occurs. The degree of slippage is greatest for Au > Ag > Cu. A related zinc complex containing two [B=C] - ligands was prepared as a further point of comparison for the η 1 coordination mode. The bonding in these new complexes has been interrogated by computational techniques (QTAIM, NBO, ETS-NOCV) and rationalised in terms of the Dewar-Chatt-Duncanson model. The combined structural and computational data provide unique insight into catalytically relevant linear d 10 complexes of Cu, Ag and Au. Slippage is proposed to play a key role in catalytic reactions of alkenes through disruption and polarisation of the p -system. Through the preparation and analysis of a consistent series of group 11 complexes, we show that variation of the metal can impact the degree of slippage and hence substrate activation.

Journal article

Kong RY, Crimmin MR, 2021, 1(st) row transition metal aluminylene complexes: preparation, properties and bonding analysis, DALTON TRANSACTIONS, Vol: 50, Pages: 7810-7817, ISSN: 1477-9226

Journal article

Garçon M, Mun NW, White AJP, Crimmin MRet al., 2021, Palladium-catalysed C-H bond zincation of arenes: scope, mechanism, and the role of heterometallic intermediates, Angewandte Chemie International Edition, Vol: 60, Pages: 6145-6153, ISSN: 1433-7851

Catalytic methods that transform C-H bonds into C-X bonds are of paramount importance in synthesis. A particular focus has been the generation of organoboranes, organosilanes and organostannanes from simple hydrocarbons (X=B, Si, Sn). Despite the importance of organozinc compounds (X=Zn), their synthesis by the catalytic functionalisation of C-H bonds remains unknown. Herein, we show that a palladium catalyst and zinc hydride reagent can be used to transform C-H bonds into C-Zn bonds. The new catalytic C-H zincation protocol has been applied to a variety of arenes-including fluoroarenes, heteroarenes, and benzene-with high chemo- and regioselectivity. A mechanistic study shows that heterometallic Pd-Zn complexes play a key role in catalysis. The conclusions of this work are twofold; the first is that valuable organozinc compounds are finally accessible by catalytic C-H functionalisation, the second is that heterometallic complexes are intimately involved in bond-making and bond-breaking steps of C-H functionalisation.

Journal article

Garçon M, Mun NW, White AJP, Crimmin MRet al., 2021, Palladium‐Catalysed C−H Bond Zincation of Arenes: Scope, Mechanism, and the Role of Heterometallic Intermediates, Angewandte Chemie, Vol: 133, Pages: 6210-6218, ISSN: 0044-8249

Journal article

Batuecas M, Gorgas N, Crimmin MR, 2021, Catalytic C-H to C-M (M = Al, Mg) bond transformations with heterometallic complexes, CHEMICAL SCIENCE, Vol: 12, Pages: 1993-2000, ISSN: 2041-6520

Journal article

Kong RY, Crimmin MR, 2021, Chemoselective C-C σ-bond activation of the most stable ring in biphenylene., Angewandte Chemie International Edition, Vol: 60, Pages: 2619-2623, ISSN: 1433-7851

The chemoselective cleavage of a six-membered aromatic ring in biphenylene is reported using an aluminium(I) complex. This type of selectivity is unprecedented. In every example of transition metal mediated C-C sigma-bond activation reported to date, the reaction occurs at the central four-membered ring of biphenylene. Insight into the origin of chemoselecitivty was obtained through a detailed mechanistic analysis (isolation of an intermediate, DFT studies, activation strain analysis). We conclude that the divergent reactivity can be attributed to differences in both the symmetry and radial extension of the frontier molecular orbitals of the aluminium(I) fragment compared to common transition metal fragments.

Journal article

Kong RY, Crimmin MR, 2021, Chemoselective C−C σ‐Bond Activation of the Most Stable Ring in Biphenylene**, Angewandte Chemie, Vol: 133, Pages: 2651-2655, ISSN: 0044-8249

Journal article

Kong RY, Crimmin MR, 2020, Cooperative strategies for CO homologation, DALTON TRANSACTIONS, Vol: 49, ISSN: 1477-9226

Journal article

Mulryan D, White AJP, Crimmin MR, 2020, Organocatalyzed fluoride metathesis, Organic Letters, Vol: 22, Pages: 9351-9355, ISSN: 1523-7060

A new organocatalyzed fluoride metathesis reaction between fluoroarenes and carbonyl derivatives is reported. The reaction exchanges fluoride (F–) and alternate nucleophiles (OAc–, OCO2R–, SR–, Cl–, CN–, NCS–). The approach provides a conceptually novel route to manipulate the fluorine content of organic molecules. When the fluorination and defluorination steps are combined into a single catalytic cycle, a byproduct free and 100% atom-efficient reaction can be achieved.

Journal article

Sheldon DJ, Coates G, Crimmin MR, 2020, Defluorosilylation of trifluoromethane: upgrading an environmentally damaging fluorocarbon, CHEMICAL COMMUNICATIONS, Vol: 56, Pages: 12929-12932, ISSN: 1359-7345

Journal article

Rekhroukh F, Chen W, Brown RK, White AJP, Crimmin MRet al., 2020, Palladium-catalysed C-F alumination of fluorobenzenes: mechanistic diversity and origin of selectivity, CHEMICAL SCIENCE, Vol: 11, Pages: 7842-7849, ISSN: 2041-6520

Journal article

Hooper TN, Brown RK, Rekhroukh F, Garcon M, White AJP, Costa PJ, Crimmin MRet al., 2020, Catalyst control of selectivity in the C-O bond alumination of biomass derived furans, CHEMICAL SCIENCE, Vol: 11, Pages: 7850-7857, ISSN: 2041-6520

Journal article

Kong RY, Crimmin MR, 2020, Activation and functionalization of C–C σ-Bonds of alkylidene cyclopropanes at main group centers, Journal of the American Chemical Society, Vol: 142, Pages: 11967-11971, ISSN: 0002-7863

Aluminum(I) and magnesium(I) compounds are reported for the C–C σ-bond activation of strained alkylidene cyclopropanes. These reactions result in the formal addition of the C–C σ-bond to main group center either at a single site (Al) or across a metal–metal bond (Mg–Mg). Mechanistic studies suggest that rather than occurring by a concerted oxidative addition, these reactions involve stepwise processes in which substrate binding to the main group metal acts as a precursor to α- or β-alkyl migration steps that break the C–C σ-bond. This mechanistic understanding is used to develop the magnesium-catalyzed hydrosilylation of the C–C σ-bonds of alkylidene cyclopropanes.

Journal article

Phillips NA, Coates GJ, White AJP, Crimmin MRet al., 2020, Defluoroalkylation of sp(3) C-F bonds of industrially relevant hydrofluoroolefins, Chemistry: A European Journal, Vol: 26, Pages: 5365-5368, ISSN: 0947-6539

A simple, one‐pot procedure is reported for the selective defluoroalkylation of trifluoromethyl alkene derivatives with aldehydes and ketones. The reaction sequence allows construction of a new C−C bond in a highly selective manner from a single sp3 C−F bond of a CF3 group in the presence of sp2 C−F bonds. The scope incorporates industrially relevant fluorocarbons including HFO‐1234yf and HFO‐1234ze. No catalyst, additives or transition metals are required, rather the methodology relies on a recently developed boron reagent. Remarkably, the boron site of this reagent plays a dual role in the reaction sequence, being nucleophilic at boron in the C−F cleavage step (SN2’) but electrophilic at boron en route to the carbon–carbon bond‐forming step (SE2’). The duplicitous behaviour is underpinned by a hydrogen atom migration from boron to the carbon atom of a carbene ligand.

Journal article

Bakewell C, Garçon M, Kong RY, OHare L, White AJP, Crimmin MRet al., 2020, Reactions of an aluminum(I) reagent with 1,2-, 1,3-, and 1,5-dienes: dearomatization, reversibility, and a pericyclic mechanism, Inorganic Chemistry, Vol: 59, ISSN: 0020-1669

Addition of the aluminum(I) reagent [{(ArNCMe)2CH}Al] (Ar = 2,6-di-iso-propylphenyl) to a series of cyclic and acyclic 1,2-, 1,3-, and 1,5-dienes is reported. In the case of 1,3-dienes, the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene-containing products. This mechanism has been examined by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4 + 1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4 + 1) cycloaddition includes styene, 1,1-diphenylethylene, and anthracene. In these cases, the diene motif is either in part, or entirely, contained within an aromatic ring and reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2-cyclononadiene or 1,5-cyclooctadiene, complementary reactivity is observed; the orthogonal nature of the C═C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavor a (4 + 1) cycloaddition. Rather, reaction pathways are determined by an initial (2 + 1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C═C π-bond, leading to complex organometallic products that incorporate fused hydrocarbon rings.

Journal article

Coates G, Rekhroukh F, Crimmin MR, 2019, Breaking carbon–fluorine bonds with main group nucleophiles, Synlett, Vol: 30, Pages: A-N, ISSN: 0936-5214

In this Account we describe a series of new reactions that we, and others, have reported that involve the transformation of C–F bonds into C–Mg, C–Al, C–Si, C–Fe and C–Zn bonds. We focus on the use of highly reactive main group nucleophiles and discuss aspects of reaction scope, selectivity and mechanism.

Journal article

Garçon M, George S, Clare B, Alison E, Richard C, White A, Crimmin Met al., 2019, A hexagonal planar transition-metal complex, Nature, Vol: 574, Pages: 390-393, ISSN: 0028-0836

Transition metal complexes are widely applied in the physical and biological sciences. They play pivotal roles in aspects of catalysis, synthesis,materials science, photophysics and bioinorganic chemistry.Our understanding of transition metal complexes originates from Alfred Werner’s realisation that their three-dimensional shape influences their properties and reactivity.1The intrinsic link between shape and electronic structure is now firmly underpinned by molecular orbital theory.2-5Despite over a century of advances in this field, transition metal complexes remain limited to a handful of well understood geometries. Archetypal geometriesfor six-coordinate transition metals are octahedral andtrigonal prismatic. Although deviations from idealbond angles and lengths are common,6alternativeparent geometries are staggeringly rare.7Hexagonal planar transition metalsare restricted to those found in condensed metallic phases,8the hexagonal pores of coordination polymers,9orclusters containing more than one transition metal in close proximity.10,11Although [Ni(PtBu)6] could beassignedas a hexagonal planar complex,12,13a molecular orbital analysis ultimately led to the conclusion that it is best described as a 16-electron complex with a trigonal planar geometry.14Here we report the isolation and structural characterisation of the first simple coordination complex in which six ligands form bonds with a central transition metal in a hexagonal planar arrangement.The discovery has the potential to open up new design principles and new ways of thinking about transition metal complexes which could impact multiple fields of science.

Journal article

Hooper TN, Lau S, Chen W, Brown RK, Garçon M, Luong K, Barrow NS, Tatton AS, Sackman GA, Richardson C, White AJP, Cooper RI, Edwards AJ, Casely IJ, Crimmin MRet al., 2019, The partial dehydrogenation of aluminium dihydrides, Chemical Science, Vol: 10, Pages: 8083-8093, ISSN: 2041-6520

The reactions of a series of β-diketiminate stabilised aluminium dihydrides with ruthenium bis(phosphine), palladium bis(phosphine) and palladium cyclopentadienyl complexes is reported. In the case of ruthenium, alane coordination occurs with no evidence for hydrogen loss resulting in the formation of ruthenium complexes with a pseudo–octahedral geometry and cis-relation of phosphine ligands. These new ruthenium complexes have been characterised by multinuclear and variable temperature NMR spectroscopy, IR spectroscopy and single crystal X-ray diffraction. In the case of palladium, a series of structural snapshots of alane dehydrogenation have been isolated and crystallographically characterised. Variation of the palladium precursor and ligand on aluminium allows kinetic control over reactivity and isolation of intermetallic complexes that contain new Pd–Al and Pd–Pd interactions. These complexes differ by the ratio of H : Al (2 : 1, 1.5 : 1 and 1 : 1) with lower hydride content species forming with dihydrogen loss. A combination of X-ray and neutron diffraction studies have been used to interrogate the structures and provide confidence in the assignment of the number and position of hydride ligands. 27Al MAS NMR spectroscopy and calculations (DFT, QTAIM) have been used to gain an understanding of the dehydrogenation processes. The latter provide evidence for dehydrogenation being accompanied by metal–metal bond formation and an increased negative charge on Al due to the covalency of the new metal–metal bonds. To the best of our knowledge, we present the first structural information for intermediate species in alane dehydrogenation including a rare neutron diffraction study of a palladium–aluminium hydride complex. Furthermore, as part of these studies we have obtained the first SS 27Al NMR data on an aluminium(I) complex. Our findings are relevant to hydrogen storage, materials chemistry and catalysis.

Journal article

Phillips NA, O'Hanlon J, Hooper TN, White AJP, Crimmin MRet al., 2019, Dihydridoboranes: Selective Reagents for Hydroboration and Hydrodefluorination, ORGANIC LETTERS, Vol: 21, Pages: 7289-7293, ISSN: 1523-7060

Journal article

Coates G, Tan HY, Kalff C, White A, Crimmin MRet al., 2019, Defluorosilylation of industrially relevant fluoroolefins using nucleophilic silicon reagents, Angewandte Chemie - International Edition, Vol: 58, Pages: 12514-12518, ISSN: 1433-7851

A number of new magnesium and lithium silyl reagents were prepared and shown to be outstanding nucleophiles in reactions with industrially relevant fluoroolefins. These reactions result in a net transformation of either sp2 or sp3 C-F bonds into C-Si bonds by two modes of nucleophilic attack (SNV or SN2'). The methods are mild, proceeding with high chemo- and regioselectivity. Mechanistic pathways are described that lead to new substitution patterns from HFO-1234yf, HFO-1234ze and HFO-1336mzz, previously inaccessible by transition metal catalysed defluorosilylation routes.

Journal article

Coates G, Tan HY, Kalff C, White AJP, Crimmin MRet al., 2019, Defluorosilylation of Industrially Relevant Fluoroolefins Using Nucleophilic Silicon Reagents, Angewandte Chemie, Vol: 131, Pages: 12644-12648, ISSN: 0044-8249

Journal article

Phillips N, White A, Crimmin M, 2019, Selective hydrodefluorination of hexafluoropropene to industrially relevant hydrofluoroolefins, Advanced Synthesis & Catalysis, Vol: 361, Pages: 3351-3358, ISSN: 1615-4150

The selective hydrodefluorination of hexafluoropropene to HFO‐1234ze and HFO‐1234yf can be achieved by reaction with simple group 13 hydrides of the form EH3 ⋅ L (E=B, Al; L=SMe2, NMe3). The chemoselectivity varies depending on the nature of the group 13 element. A combination of experiments and DFT calculations show that competitive nucleophilic vinylic substitution and addition‐elimination mechanisms involving hydroborated intermediates lead to complementary selectivities.

Journal article

Garcon M, Bakewell C, White AJP, Crimmin MRet al., 2019, Unravelling nucleophilic aromatic substitution pathways with bimetallic nucleophiles, Chemical Communications, Vol: 55, Pages: 1805-1808, ISSN: 1359-7345

The reaction of a metal complex containing a polar Fe–Mg bond with 2-(pentafluorophenyl)pyridine leads to selective C–F bond activation. A stepwise SNAr mechanism involving attack of the bimetallic nucleophile on the electron-deficient aromatic ring has been identified by DFT calculations. Despite the long and rich history of metal anions in organic synthesis, this is the first time the SNAr mechanism has been elucidated in detail for metal-based nucleophiles.

Journal article

Bakewell C, White AJP, Crimmin MR, 2019, Reversible alkene binding and allylic C–H activation with an aluminium(i) complex, Chemical Science, Vol: 8, Pages: 2452-2458, ISSN: 2041-6520

The monomeric molecular aluminium(I) complex 1 [{(ArNCMe)2CH}Al] (Ar = 2,6-di-iso-propylphenyl) reacts with a series of terminal and strained alkenes including ethylene, propylene, allylbenzene and norbornene to form alkene bound products. Remarkably all these reactions are reversible under mild conditions (298–353 K) with alkene binding being disfavoured at higher temperatures due to the positive reaction entropy. Van't Hoff analyses have allowed quantification of the binding events with Image ID:c8sc04865g-t1.gif. Calculations and single crystal X-ray diffraction studies are consistent with the alkene bound species being metallocyclopropane complexes. Alkene binding involves a reversible redox process with changes from the +1 to +3 aluminium oxidation state. Under more forcing conditions the metallocyclopropane complexes undergo non-reversible allylic C–H bond activation to generate aluminium(III) allyl hydride complexes. This represents a rare example of redox-based main group reactivity in which reversible substrate binding is followed by a further productive bond breaking event. Analysis of the mechanism reveals a reaction network in which alkene dissociation and reformation of 1 is required for allylic C–H activation, a realisation that has important implications for the long-term goal of developing redox-based catalytic cycles with main group compounds.

Journal article

Kong RY, Crimmin MR, 2019, Reversible insertion of CO into an aluminium–carbon bond, Chem. Commun., Vol: 55, Pages: 6181-6184

A [2.2.1] aluminium metallobicycle is capable of reversibly inserting CO to form a [2.2.2] metallobicycle at 100 °C. Computational studies reveal a highly asynchronous, but concerted, transition state for CO insertion. The coordination of CO to aluminium precedes C–C bond formation. The reversible migratory insertion of CO at aluminium thus mimics well-established transition-metal reactivity.

Journal article

Lau S, White A, Casely I, Crimmin Met al., 2018, Tunable binding of dinitrogen to a series of heterobimetallic hydride complexes, Organometallics, Vol: 37, Pages: 4521-4526, ISSN: 0276-7333

The reaction of [Ru(H)2(N2)2(PCy3)2] (1) with β-diketiminate stabilized hydrides of Al, Zn, and Mg generates a series of new heterobimetallic complexes with either H2 or N2 ligated to the ruthenium center. Changing the main-group fragment of the M·Ru-N2 (M = Al, Zn, Mg) complexes can subtly alter the degree of binding, and therefore activation, of the diatomic ligand, as evidenced by the νN≡N absorptions in the infrared data. Experimental and computational data rationalize this tunable binding; decreasing the electronegativity of the main group in the order Al > Zn > Mg infers greater ionic character of these M·Ru-N2 complexes, and this in turn results in greater destabilization of the frontier molecular orbitals of ruthenium and therefore greater Ru(4d) → π*(N2) back-donation.

Journal article

Crimmin MR, Coates G, Bakewell C, Ward B, White Aet al., 2018, Reactions of fluoroalkanes with Mg-Mg bonds: scope, sp3C-F / sp2C-F coupling and mechanism, Chemistry - A European Journal, Vol: 24, Pages: 16282-16286, ISSN: 0947-6539

sp3C-F bonds of fluoroalkanes (7 examples; 1o, 2o and 3o) undergo addition to a low-valent Mg-Mg species generating reactive organomagnesium reagents. Further reactions with a series of electrophiles results in a net C-F to C-B, C-Si, C-Sn or C-C bond transformation (11 examples, diversity). The new reactivity has been exploited in an unprecedented one-pot magnesium-mediated coupling of sp3C-F and sp2C-F bonds. Calculations suggest that the sp3C-F bond activation step occurs by frontside nucleophilic attack of the Mg-Mg reagent on the fluoroalkane.

Journal article

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