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Dr Andrew Wheatley

Portrait of aehw2

Our research interests focus on understanding the structure, synthesis and reactivity of mixed-metal organometallic compounds and nanocatalysts.

 

Organometallics for synthesis

We are interested in the activities of molecular organometallic reagents and have used homo- and heterometallic reagents including Li-Al and Li-Zn systems to fabricate hydridic clusters and to function as chemoselective bases. We work on this with teams in Tokyo, Rennes and Manchester. Recent major advances include:

1) the first demonstration that directed benzylic lithiation can be used to generate tertiary carbanions (below right) and,

2) the combination of CuCN with organolithium reagents to give bimetallic bases such as (TMP)2Cu(CN)Li2.THF (TMP = 2,2,6,6-tetramethylpiperidide; below left) that have applications in directed cupration and C–C bond formation.

 

For the first tertiary carbanion syntheses by directed metalation and a comparison of anion structures in the solid state and in solution see Chem. Eur. J., 2011, 17, 8078 and 2012, 18, 11036.

See J. Am. Chem. Soc., 2007, 129, 15102, Organometallics, 2009, 28, 38 and Angew. Chem. Int. Ed., 2012, 51, 12081 for advances in lithium amidocuprate structural and mechanistic chemistry and Chem. Eur. J., 2011, 17, 13284 for the applications of lithium cuprates in the elaboration of halopyridines.

Recently we have established the existence of adducts that may help to explain how cuprates of the type (amide)2Cu(Cl)Li2.L (below left; amide = TMP, L = Et2O) can exclude LiX to give highly active (amide)2CuLi.L. Steric effects associated with the amide ligand are thought to be crucial to controlling structure and are suggested if DMP (= cis-2,6-dimethylpiperidide) is used in place of TMP (below right).

See Chem. Eur. J., 2014, 20, ASAP article for new types of lithium amidocuprate adducts.

 

Heterogeneous nanocatalysis

The ability to access stable and compositionally and dimensionally controllable metallic nanoparticles promises applications in catalysis. We prepare metal nanoparticles (e.g. Au, Cu, Pd, CuM, PdM, M = Sn, Zn…) and use them to achieve controllably functional surfaces by deposition or encapsulation in mesostructured thin films (illustrated below). In collaboration with the Technical University of Eindhoven and Queen's University, NI, applications of the resulting microreactors have been developed in the areas of selective hydrogenation, nanotube growth, and fine chemicals synthesis.

See Lab Chip, 2009, 9, 503 for capillary microreactors wall-coated with mesoporous catalyst supports. For the immobilization of Cu catalysts (see below) and microfluidic Ullmann SNAr-type C-O coupling reactions see Chem. Eur. J., 2012, 18, 1800.

 

 

We are also interested in fundamental aspects of nanoparticle synthesis and structure. Recently, we have successfully fabricated oxidatively stable Cu-based nanocatalysts as evidenced by XRD and XPS (below). By introducing Zn we have also achieved CuZn nanoparticles with differing intermetallic ratios and predicted upper d-band energies for Cu. Cu-based catalysts were successfully deployed in multicomponent 1,3-dipolar cycloaddition reactions, yielding 1,2,3-triazoles using unprecedentedly low catalyst loadings and under facile conditions.

 

See Dalton Trans., 2010, 6496 for the development of new routes towards Cu-based nanosystems and Nanoscale, 2013, 5, 342 for further advances in particle synthesis and stability and the application of Cu-based catalysts to triazole formation.

Our interest in Cu-based nanoparticles, including how they progressively oxidize, has been reflected in work on the passivation of metal nanoparticles towards degenerative processes.  As part of a new study into the preparation of magnetic nanoparticles for applications in catalysis we have recently fully characterized monodisperse Co seeds encapsulated by Fe3O4 and established the presence of a sub-surface carbon layer:

The presence of this layer may have implications for core stability (the Co has been shown to be oxidatively stable for up to a year and counting) and the ability to favour the synthesis of core-shell heterostructures. This is the subject of ongoing work that seeks to establish the generality of this encapsulation procedure.

See Nanoscale, 2013, 5, 5765 for the synthesis and detailed characterization of Co-Fe3O4 nanoparticles, including using EFTEM and EELS point scan data (below) that proves the existence of intraparticle carbon.

Publications

Spectroscopic route to monitoring individual surfactant ions and micelles in aqueous solution: A case study
J Geng, BFG Johnson, AEH Wheatley, JK Luo – Central European Journal of Chemistry (2014) 12, 307
Structural Effects in Lithiocuprate Chemistry: The Elucidation of Reactive Pentametallic Complexes
PJ Harford, AJ Peel, JP Taylor, S Komagawa, PR Raithby, TP Robinson, M Uchiyama, AEH Wheatley – Chemistry - A European Journal (2014)
Reactions of Cp2M (M = Ni, V) with dilithium diamido-aryl reagents; Retention and oxidation of the transition metal ions
FA Stokes, MA Vincent, IH Hillier, TK Ronson, A Steiner, AE Wheatley, PT Wood, DS Wright – Dalton transactions (Cambridge, England : 2003) (2013) 42, 13923
A kinetic study on the Cu(0)-catalyzed ullmann-type nucleophilic aromatic substitution C-O coupling of potassium phenolate and 4-chloropyridine
F Benaskar, V Engels, NG Patil, EV Rebrov, J Meuldijk, V Hessel, LA Hulshof, AEH Wheatley, JC Schouten – Industrial and Engineering Chemistry Research (2013) 52, 18206
AC magnetic heating of superparamagnetic Fe and Co nanoparticles
A Lukawska, Z Jagoo, G Kozlowski, Z Turgut, H Kosai, A Sheets, T Bixel, A Wheatley, P Abdulkin, B Knappett, T Houlding, V Degirmenci – Defect and Diffusion Forum (2013) 336, 159
Efficient two-step access to azafluorenones and related compounds
N Marquise, PJ Harford, F Chevallier, T Roisnel, AEH Wheatley, PC Gros, F Mongin – Tetrahedron Letters (2013) 54, 3154
Simple Trivalent Organoaluminum Species: Perspectives on Structure, Bonding, and Reactivity
J Lewinski, AEH Wheatley – MODERN ORGANOALUMINUM REAGENTS: PREPARATION, STRUCTURE, REACTIVITY AND USE (2013) 41, 1
Synthesis of azafluorenones and related compounds using deprotocupration-aroylation followed by intramolecular direct arylation
N Marquise, PJ Harford, F Chevallier, T Roisnel, V Dorcet, A-L Gagez, S Sablé, L Picot, V Thiéry, AEH Wheatley, PC Gros, F Mongin – Tetrahedron (2013) 69, 10123
Systematic Control of Size and Morphology in the Synthesis of Gold Nanoparticles
P Abdulkin, TL Precht, BR Knappett, HE Skelton, DA Jefferson, AEH Wheatley – Particle and Particle Systems Characterization (2013)
New routes to Cu(i)/Cu nanocatalysts for the multicomponent click synthesis of 1,2,3-triazoles
P Abdulkin, Y Moglie, BR Knappett, DA Jefferson, M Yus, F Alonso, AE Wheatley – Nanoscale (2013) 5, 342
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Research Group

Research Interest Group

Telephone number

01223 763966

Email address

aehw2@cam.ac.uk