Lancaster, Simon - University of East Anglia

个人简介

Prof Lancaster obtained a BSc 1991, MSc 1992 and PhD 1995, from the University of East Anglia. In 1996 the RSC awarded him the Laurie Vergnano prize for the best contribution to Inorganic Chemistry by a young researcher for his work on Early Transition Metal Alkyl Cations and their role in Polymerisation Catalysis. He then spent four years as a research officer at the University of Leeds. In February 2000 Prof Lancaster returned to UEA as a Lecturer in Inorganic Chemistry and was promoted to Senior Lecturer in 2009 and Professor in 2014. He is currently Director of Admissions. Prof Lancaster studies organometallic chemistry because it presents the richest seam of novelty and chemical adventure and provides us with the most reactive molecules and a plethora of fascinating bonding modes and structures found nowhere else in chemistry. We are interested in developing new organometallic complexes and their pre-cursors for applications as diverse as catalysing the dehydrocoupling polymerisation of ammoniaboranes, predicting, rationalising and ultimately controlling supramolecular architectures and using the synergy between main group and transition metal centres to activate small molecules. This research has been funded by EPSRC, British Council, European Commission (RTN), Akzo Nobel and has led to many collaborations including: Dr Gregory Wildgoose, Dr David L. Hughes, Dr Joseph A. Wright, Prof. Manfred Bochmann (UEA), Dr Robbert Duchateau (Eindhoven), Prof Annie K. Powell (Karlsruhe), Dr Richard Woudenberg (Akzo Nobel). Prof Lancaster is a dedicated and innovative teacher and has been rewarded by UEA’s Sir Geoffrey and Lady Allen teaching excellence award. His application of technology to support student engagement has been supported by Teaching Fellowships and funding from both the Higher Education Academy and the University Annual Fund. He is the recipient of the 2013 Royal Society of Chemistry (RSC) Higher Education Award and in 2013 was recognised by the Higher Education Academy as a National Teaching Fellow. He is an external examiner at Hull University. Prof Lancaster plays a leading role in promoting technology enhanced learning and teaching at UEA and on a national level. He is external affairs officer for the Association of National Teaching Fellows and a member of the Education Division of the RSC. He is a partner representative for UEA within FutureLearn, where he is facilitating UEA’s Massive Open Online Courses (MOOCs). He is a member of UEA’s Taught Programme Policy Group and UK Professional Standards Framework steering group.

研究领域

Homogenous Catalysis As well as our development of poorly coordinating counteranions for highly electrophilic catalysts our resarch has recently focussed on the generation of hybrid (heteroligated) octahedral group 4 alkene polymerisation catalysts. Our objective is to combine the properties of highly active catalysts with high comonomer incorporation systems to generate new or existing copolymer materials with very high productivities. This approach has proven to be remarkably successful. The best examples to date are the (salicylaldiminato)(pyrrolylaldiminato)titanium catalysts. The synthesis, structure and ethene polymerization activity of octahedral heteroligated (salicylaldiminato)(-ketiminato)titanium complexes: The X-ray crystal structure of {3-But-2-(O)C6H3CHN(Ph)}{(Ph)NC(Me)C(H)C(Me)O}TiCl2. D. A. Pennington, R. W. Harrington, W. Clegg, M. Bochmann, S. J. Lancaster, J. Organomet. Chem., accepted. Salicylaldiminato Pyrrolylaldiminato Group 4 Metal Alkene Polymerization Catalysts: Combining High Activity with High Comonomer Incorporation. D. A. Pennington, S. J. Coles, M. B. Hursthouse, M. Bochmann, and S. J. Lancaster, Macromol. Chem. Rapid. Commun., accepted. Hybrid catalysts: synthesis, structure and ethene polymerisation activity of salicylaldiminato)(pyrrolylaldiminato) titanium complexes. D. A. Pennington, S. J. Coles, M. B. Hursthouse, M. Bochmann and S. J. Lancaster, Chem. Commun. 2005, 3150 – 3152. Very Weakly Basic Anions Organometallic Lewis acids, notably the perfluorophenyl borane B(C6F5)3, are well known as activators for homogeneous group 4 metal polymerisation catalysts. They are also very useful building blocks for the construction of extremely weakly coordinating anions. Our approach consists of binding two or more B(C6F5)3units to a central anionic linker. Examples are: [CN{B(C6F5)3}2]‑, a linear anion which produced one of the most active ethylene polymerisation catalyst yet reported while our preferred anion is [H2N{B(C6F5)3}2]‑ since it shows comparable stability to the synthetically much less accessible [B(C6F5)4]‑ and has much better crystallisation behaviour (ORTEP below left, space filling below right). The effectiveness of all these systems in stabilising extremely electrophilic metal centres depends on the extensive delocalisation of the negative charge over a very large volume, as shown below on the left by the van-der-Waals volumes of [N(CN)2{B(2-C6F4C6F5)3}2]‑ in comparison with [Cp2ZrMe]+: The resulting complex anions are essentially non-coordinating and support extremely electrophilic cationic centres. The best-known of these are group 4 metallocenium ions, [Cp2M-R]+ (M = Ti, Zr, Hf). Key references Evidence for Mixed-Ion Clusters in Metallocene Catalysts: Influence on Ligand Exchange Dynamics and Catalyst Activity C. Alonso-Moreno, S. J. Lancaster, C. Zuccaccia, A. Macchioni,*, and M. Bochmann*J. Am. Chem. Soc. 2007, 129, 9282-9283. The synthesis of new weakly coordinating diborate anions: anion stability as a function of linker structure and steric bulk. M. H. Hannant, J. A. Wright, S. J. Lancaster, D. L. Hughes, P. N. Horton and M. Bochmann Dalton Transactions, 2006, 2415-2426 Anion Effects on Activity and Stereoselectivity in Propene Polymerisations Catalysed by C2-symmetric and “Oscillating” Catalysts. A. Rodriguez-Delgado, M. D. Hannant, S. J. Lancaster and M. Bochmann, Macromol.Chem. Phys. 2004, 205, 334 - 346. Role of B(C6F5)3 in catalyst activation, anion formation, and as C6F5 transfer agent. M. Bochmann, S. J. Lancaster, M. Hannant, A. Rodriguez, M. Schormann, D. A. Walker and T. J. Woodman, Pure Appl. Chem.2003, 75, 1183 – 1195. [H2N{B(C6F5)3}2]‑: A New, Remarkably Stable Diborate Anion for Metallocene Polymerization Catalysts. S. J. Lancaster, A. Rodriguez, A. Lara-Sanchez, M. D. Hannant, D. A. Walker, D. L. Hughes and M. Bochmann,Organometallics 2002, 21, 451 – 453. Synthesis, Structures and Reactivity of Weakly Coordinating Anions with Delocalized Borate Structure: The Assessment of Anion Effects in Metallocene Polymerization Catalysts. J. Zhou, S. J. Lancaster, D. A. Walker, S. Beck, M. Thornton-Pett and M. Bochmann, J. Am. Chem. Soc. 2001, 123, 223 – 237. Zwitterions Many of the species we are interested in are highly electrophilic cations which means we need to concern ourselves with the anion and potential coordination. Ions are always going to be less soluble in non-polar solvents than neutral species. By introducing an anionic substituent into the ligand backbone one can prepare neutral zwitterions where previously the complexes would have been cationic in nature. At best this tethers the anionic group where it can not coordinate to the metal centre, at worst it still produces a material that is much more soluble than it would otherwise have been. The rationale and approach to zwitterion formation can be extended far beyond the realm of metallocene catalysts. We are currently looking at zwitterions as alternatives to discrete cations and anions in a number of catalysts and materials applications. Activated Ammonia One of the most exciting areas is research into the reactivity of the ammonia adduct of tris(pentafluorophenyl)boron, which reacts with metal amides to give amidoborate complexes. These can be regarded as zwitterionic complexes of an 'anionic amine' ligand. Key references Tris(dimethylamido)bis(dimethylamine)titanium(IV) chloridobis(dimethylamine)[tris(pentafluorophenyl)boron--amido][tris(pentafluorophenyl)boron--nitrido]titanate(IV) toluene solvate. A. J. Mountford, S. J. Lancaster, S. J.Coles Acta Cryst. C, 2007, 63, m401-m404. The Synthesis, Structure and Reactivity of B(C6F5)3-Stabilised Amide (MNH2) Complexes of the Group 4 Metals. A. J. Mountford, W. Clegg, S. J. Coles, R. W. Harrington, P. N. Horton, S. M. Humphrey, M. B. Hursthouse, J. A. Wright, S. J. Lancaster Chem. Eur. J. 2007, 13, 4535-4547. New titanium and zirconium complexes with M–NH2 bonds formed by facile deprotonation of H3N•B(C6F5)3. A. J. Mountford, W. Clegg, R. W. Harrington, S. M. Humphrey and S. J. Lancaster Chem. Commun. 2005, 2044-2046. The synthesis of half-sandwich bis(pentafluorophenyl)boryl-substituted cyclopentadienyl zirconium, niobium and tantalum complexes and the isolation and molecular structure of a zwitterionic niobocene. S. J. Lancaster and D. L. Hughes Dalton Trans., 2003, 1779 – 1789. Ansa-Metallocenes with B‑N and B‑P Linkages: The Importance of N‑H••••F‑C Hydrogen Bonding in Pentafluorophenyl Boron Compounds S. J. Lancaster, A. J. Mountford, D. L. Hughes, M. Schormann and M. Bochmann, J. Organomet. Chem. 2003, 680, 193 – 205 (invited paper). Anionic ansa-Zirconocenes with Pentafluorophenyl-Substituted Borato Bridges. S. J. Lancaster and M. Bochmann, Organometallics 2001, 20, 2093 – 2101. Supramolecular Organometallic Chemistry We have recently started to explore the preparation of supramolecular architectures for materials applications through purely intermolecular interactions between Lewis basic adducts of perfluoroaryl substituted organometallics. Perfluoroaryl groups bonded to metal centres can participate in a remarkable array of truly intermolecular (as opposed to dative) interactions, which connect molecules to form supramolecular assemblies. Packing diagram illustrating the one-dimensional chains in (cyclo-C5H10NH)2Zn(C6F5)2 formed by a PhF•••PhF stacking motif. A sheet of molecules of (Me2NH)2Zn(C6F5)2 connected through the illustrated N‑H•••F interactions. The two ligands labeled ‘•’ are of a neighboring sheet and have parallel overlapping PhF•••PhF ring interactions with groups of the first sheet.

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Homogenous Catalysis As well as our development of poorly coordinating counteranions for highly electrophilic catalysts our resarch has recently focussed on the generation of hybrid (heteroligated) octahedral group 4 alkene polymerisation catalysts. Our objective is to combine the properties of highly active catalysts with high comonomer incorporation systems to generate new or existing copolymer materials with very high productivities. This approach has proven to be remarkably successful. The best examples to date are the (salicylaldiminato)(pyrrolylaldiminato)titanium catalysts. Very Weakly Basic Anions Organometallic Lewis acids, notably the perfluorophenyl borane B(C6F5)3, are well known as activators for homogeneous group 4 metal polymerisation catalysts. They are also very useful building blocks for the construction of extremely weakly coordinating anions. Our approach consists of binding two or more B(C6F5)3units to a central anionic linker. Examples are: [CN{B(C6F5)3}2]‑, a linear anion which produced one of the most active ethylene polymerisation catalyst yet reported while our preferred anion is [H2N{B(C6F5)3}2]‑ since it shows comparable stability to the synthetically much less accessible [B(C6F5)4]‑ and has much better crystallisation behaviour (ORTEP below left, space filling below right). The effectiveness of all these systems in stabilising extremely electrophilic metal centres depends on the extensive delocalisation of the negative charge over a very large volume, as shown below on the left by the van-der-Waals volumes of [N(CN)2{B(2-C6F4C6F5)3}2]‑ in comparison with [Cp2ZrMe]+: The resulting complex anions are essentially non-coordinating and support extremely electrophilic cationic centres. The best-known of these are group 4 metallocenium ions, [Cp2M-R]+ (M = Ti, Zr, Hf). Zwitterions Many of the species we are interested in are highly electrophilic cations which means we need to concern ourselves with the anion and potential coordination. Ions are always going to be less soluble in non-polar solvents than neutral species. By introducing an anionic substituent into the ligand backbone one can prepare neutral zwitterions where previously the complexes would have been cationic in nature. At best this tethers the anionic group where it can not coordinate to the metal centre, at worst it still produces a material that is much more soluble than it would otherwise have been. The rationale and approach to zwitterion formation can be extended far beyond the realm of metallocene catalysts. We are currently looking at zwitterions as alternatives to discrete cations and anions in a number of catalysts and materials applications. Activated Ammonia One of the most exciting areas is research into the reactivity of the ammonia adduct of tris(pentafluorophenyl)boron, which reacts with metal amides to give amidoborate complexes. These can be regarded as zwitterionic complexes of an 'anionic amine' ligand. Supramolecular Organometallic Chemistry We have recently started to explore the preparation of supramolecular architectures for materials applications through purely intermolecular interactions between Lewis basic adducts of perfluoroaryl substituted organometallics. Perfluoroaryl groups bonded to metal centres can participate in a remarkable array of truly intermolecular (as opposed to dative) interactions, which connect molecules to form supramolecular assemblies. Packing diagram illustrating the one-dimensional chains in (cyclo-C5H10NH)2Zn(C6F5)2 formed by a PhF•••PhF stacking motif. A sheet of molecules of (Me2NH)2Zn(C6F5)2 connected through the illustrated N‑H•••F interactions. The two ligands labeled ‘•’ are of a neighboring sheet and have parallel overlapping PhF•••PhF ring interactions with groups of the first sheet.