Professor Richard Henderson
Professor of Inorganic Chemistry

  • Email: richard.henderson@ncl.ac.uk
  • Telephone: +44 (0) 191 208 6636
  • Fax: +44 (0) 191 208 6929
  • Address: School of Chemistry,
    Newcastle University,
    Newcastle upon Tyne,
    NE1 7RU

Background

1976-1977: Postdoctoral Fellow (UCL)
1977-1979: Postdoctoral Fellow (Leeds)
1979-1999: Project Leader at AFRC Nitrogen Fixation Laboratory

Roles and Responsibilities

Professor of Inorganic Chemistry

Qualifications

1973 B.Sc. (Hons) Chemistry, University College London
1976 Ph.D. Chemistry, University College London

Previous Positions

1976 - 1977 Postdoctoral Fellow with A G Davies FRS, University College London
1977- 1979 Postdoctoral Fellow with A G Sykes FRS, University of Leeds
1979-1999 Project Leader, AFRC Nitrogen Fixation Laboratory
1999 – present Professor of Inorganic Chemistry, University of Newcastle

Memberships

Fellow of the Royal Society of Chemistry

Member of American Chemical Society 

Honours and Awards

1985 - 1995 Honorary Lecturer, University of Sussex
1995 – 1999 Honorary Lecturer, University of East Anglia
1993 RSC Award in Inorganic Reaction Mechanisms
1999 Fellow Royal Society of Chemistry

Research Interests

My main interest is in the area of MECHANISTIC INORGANIC CHEMISTRY. In particular the binding and activation of small molecules at transition metal sites. This is a broad topic which is relevant to areas as diverse as BIOINORGANIC and ORGANOMETALLIC chemistry. Current research interests are detailed below.

Synthetic Fe-S-Based Clusters
Iron-sulfur-based clusters are found in a variety of metalloenzymes where they play roles as diverse as: electron-transfer mediators; iron sensors, and the substrate binding site in redox and non-redox enzymic reactions.

In order to understand how the clusters operate in enzymic reactions it is necessary to define their fundamental chemistry outside the polypeptide matrix. Many of the clusters in these metalloenzymes can be synthesised in the laboratory from simple reagents.

Our initial studies on synthetic Fe-S-based clusters involved simple substitution reactions of the terminal thiolate and halido-ligands, and the protonation and binding of small molecules and ions (eg L = halide, CO, N2O, N3-, CN-). The binding of protons and small molecules are not associated with an appreciable change in the electronic spectrum of the cluster and so we have to study these reactions indirectly; effectively by measuring the effect that these species have on the rate of the substitution reactions of these cluster, as illustrated in the Figure. The binding of these molecules and ions to Fe-S-based clusters is important since several of these species are substrates for enzymes containing Fe-S-based clusters. Studying a variety of clusters allows us to reasonably suggest the identity of the cluster binding sites for these molecules and ions.

Extracted FeMo-cofactor
Nitrogenase is a multi-component metalloenzyme which converts molecular nitrogen into ammonia by a sequence of coupled electron- and proton-transfer reactions. The crystal structures of all the component proteins have been determined and shown in Figure 4 is a portion of the structure showing the clusters involved: an Fe4S4 cube (electron transfer mediator); a unique Fe8S7 cluster (P-cluster, electron storage) and a unique MoFe7S9 cluster (FeMo-cofactor, substrate binding site).

This cluster is bound to the polypeptide matrix via a cysteinate to the unique tetrahedral Fe (all other Fe's are three coordinate), and a histidine to the Mo atom. The Mo atom is six coordinate and the remainder of the coordination sphere is made up from a R-homocitrate molecule acting as a bidentate ligand. The skeleton structure of FeMo-cofactor is shown in the Figure.

FeMo-cofactor can be removed, intact, from the protein and extracted into N-methylformamide (NMF). This extraction must involve cleavage of the Fe-cysteinate and Mo-histidine bonds, and what we reasonably assume is that in the extract these positions are occupied by NMF.

The approach we have developed to investigate the reactivity of this cluster is adapted from our studies with the synthetic Fe-S-based clusters (above). The reaction of extracted FeMo-cofactor with PhS- occurs exclusively at the unique tetrahedral Fe site as shown in the Figure. By measuring how the rate of this reaction is affected by binding of molecules and ions to the cofactor we can "map out" where these species bind on the cluster, and how changing the polycarboxylate affects the reactivity.

Regio-, Stereo- and Product-Specific Protonation
For some time we have been investigating the protonation of small molecules coordinated to electron-rich transition metal sites such as {M(Ph2PCH2CH2PPh2)2} (M = Fe, Ru, Os, Mo, W, Re). The ligands which have been of particular interest include: N2, RNC, RCN, alkynes, alkenes, unsaturated hydrocarbon residues and hydrides.

By studying the mechanisms with a variety of different, but analogous, complexes we can build up a detailed picture of: (i) all the possible ways in which the ligand is transformed by protonation; (ii) which are the most favoured sites of protonation (metal versus different sites on the ligand) and (iii) how controlling the system (variation of ancillary ligands or the concentration of acid) can favour one pathway over another. For example, our studies on alkene complexes have shown how simply altering the concentration of acid can result in the production of either alkanes, isomerised alkenes or even alkynes, as summarised in the Figure.

Recently we have started to study the protonation of ligands bound to Ni(II)-phosphine sites; in particular looking at the reactivity of hydride and alkyl ligands.

Postgraduate Supervision

Adrian Dunford 1999-2002
Lin Ping 2000-2005
Valerie Autissier 2000-2004
Brendan Garrett 2003-2007
Katie Bates 2004-2008

Ahmed Alwaaly 2010-present

Thaer Al-Rammahi 2013-present

Esteem Indicators

1. Invitations to give section/keynote lectures at International Meetings including: ICCC36, Mexico; Reaction Mechanisms VII, Dublin; GRC Nitrogen Fixation Meeting 2002, USA; Inorganic Mechanisms Meeting, Greece, 2004; RSC Annual Conference, Birmingham 2001; RSC Education Meeting 2007

2. Invitations to Contribute Chapters to Books and Articles in Special editions of Journals including: Recent Advances in Hydride Chemistry (ed. M. Peruzzini and R. Poli), Elsevier, 2001, “Metal Hydride Intermediates in Hydrogenases and Nitrogenases”, p463-505; Nitrogen Fixation at the Millenium (ed. G. J. Leigh), Elsevier, 2002, “Advances Towards the Mechanism of Nitrogenases”, p223-261; “Kinetic Studies on the Reactions of HCl with trans-[MoL(CNPh)(Ph2PCH2CH2PPh2)2] (L = N2, H2 or CO), M.-C. Rosenblat and R. A. Henderson, Inorganica Chimica Acta, 2002, 331, 270-278 (Special Issue for A. G. Sykes); “Mechanistic Studies on Synthetic Fe-S-Based Clusters and their Relevance to the Action of the Nitrogenases”, R. A. Henderson*, Chemical Reviews, 2005, 105, 2365-2438 (Special Issue on Inorganic Mechanisms); “Proton Transfer to Synthetic Fe-S-Based Clusters”, R. A. Henderson*, Coord. Chem. Rev., 2005, in press (Special Issue for ICCC Keynote Lecturers).

3. Chairman of the Royal Society of Chemistry Inorganic Mechanisms Discussion Group (1999-2003).

4. Organising Committee of conferences including: IRMDG Galway, Eire, 2001; Dalton Discussion No. 4, Kloster Banz, Germany, 2002; Inorganic Mechanisms Meeting, Newcastle, UK, 2003.

5. Chemistry Education: External Examiner for University of Malaysia (2004-2007); Reviewer of new edition of Shriver and Atkins.

6. Invitations to give departmental seminars including: University of Birmingham; University of Edinburgh; University of St Andrews; University of Warwick.

7. External Examiner for PhD including: University of St Andrews; Royal College of Surgeons, Dublin; University of East Anglia; Universite de Brest, France

Undergraduate Teaching

CHY1301 Inorganic and Structural Chemistry

CHY2301 Redox Mechanisms
CHY3401 Problem Solving A
CHY3402 Problem Solving B
CHY3007 Chemical Biology

CHY8430 Advanced Problem Solving