1990 …2020

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Personal profile

Research interests

Computational Organometallic Chemistry

Research uses computational chemistry to model reaction mechanisms in transition metal organometallic chemistry. Methods employed include density functional theory, hybrid QM/MM calculations and molecular dynamics. We aim to understand challenging bond activation processes (C-H and C-F bond cleavage), rationalise unusual reactivity patterns and model multi-step catalytic cycles. Research is usually carried out in close collaboration with experimental chemists.

1. Ambiphilic Metal-Ligand Assisted (AMLA) C-H Activation

We have developed the concept of Ambiphilic Metal-Ligand Assisted (AMLA) C-H activation. In this process an agostic interaction to an unsaturated metal centre combines with H-bonding to a basic co-ligand to facilitate C-H bond cleavage. With aromatic C-H activation at [Pd(OAc)2] this mechanism supersedes the long-proposed Wheland-type intermediate.  AMLA can account for facile C-H bond cleavage of both e--deficient and e--rich aromatic substrates at a range of late transition metal centres.

Figure 1. Computed agostic Intermediate in the AMLA-6 C-H Activation of dimethylbenzylamine at [Pd(OAc)2].

2. Metallophosphoranes and Aromatic C-F Bond Activation

We have defined novel ligand-assisted mechanisms for breaking the strong C-F bond of fluoroaromatics. This process involves nucleophilic attack by an e--rich metal centre with addition of a C-F bond over the M-L moiety, where L can be PR3, SiR3 or BR2. For L= PR3metallophosphoranes, [LnM-(PFR3)], are formed as intermediates or transition states. Metallophosphoranes also play a role in the unusual M-F/P-R exchange reactions, such as the interconversion of [RhF(PPh3)3] to [Rh(Ph)(PFPh2)(PPh3)2].

 

Figure 2. The central role of metallophosphoranes in phosphine-assisted C-F bond activation and F/R exchange processes.

3. Ruthenium N-Heterocyclic Carbene (NHC) Complexes in Catalysis

NHC ligands often confer enhanced reactivity on metal complexes. An example is the hydrodefluorination of C6F5H to give 1,2-C6F4H2 catalysed by [Ru(H)2(CO)(NHC)(PR3)2] species. Calculations show this unusual ortho-selectivity arises from a nucleophilic attack mechanism where the hydride ligand (and not the metal) acts as the reacting species. Calculations also aim to understand the stability of NHC ligands towards metal-based decomposition reactions such as C-H, C-C and C-N activation.

 

Figure 3. Nucleophilic attack of a hydride ligand at the ortho position of C6F5H.

Roles & Responsibilities

Research Group Contact Details

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Research Output

Accurate computed spin-state energetics for Co(iii) complexes: implications for modelling homogeneous catalysis

Neale, S. E., Pantazis, D. A. & Macgregor, S. A., 21 May 2020, In : Dalton Transactions. 49, 19, p. 6478-6487 10 p.

Research output: Contribution to journalArticle

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    A Structurally Characterized Cobalt(I) σ-Alkane Complex

    Boyd, T. M., Tegner, B., Tizzard, G., Martinez-Martinez, A., Neale, S., Hayward, M., Coles, S., Macgregor, S. & Weller, A. S., 6 Apr 2020, In : Angewandte Chemie International Edition. 59, 15, p. 6177-6181 5 p.

    Research output: Contribution to journalArticle

  • Unexpected Vulnerability of DPEphos to C-O Activation in the Presence of Nucleophilic Metal Hydrides

    Cybulski, M., Beattie, N., Macgregor, S., Mahon, M. & Whittlesey, M., 19 May 2020, In : Chemistry - A European Journal.

    Research output: Contribution to journalArticle

  • Zn-Promoted C-H Reductive Elimination and H2 Activation via a Dual Unsaturated Heterobimetallic Ru-Zn Intermediate

    Miloserdov, F. M., Rajabi, N. A., Lowe, J. P., Mahon, M. F., Macgregor, S. A. & Whittlesey, M. K., 1 Apr 2020, In : Journal of the American Chemical Society. 142, 13, p. 6340-6349 10 p.

    Research output: Contribution to journalArticle

  • A Career in Catalysis: Odile Eisenstein

    Balcells, D., Clot, E., Macgregor, S. A., Maseras, F. & Perrin, L., 1 Nov 2019, In : ACS Catalysis. 9, 11, p. 10375-10388 14 p.

    Research output: Contribution to journalArticle

  • Prizes

    Ludwig Mond Award

    Stuart Alan Macgregor (Recipient), 1 May 2019

    Prize: Prize (including medals and awards)

  • Activities

    Structure and Bonding (Journal)

    Stuart Alan Macgregor (Editorial board member)
    1 Jan 201931 Dec 2022

    Activity: Publication peer-review and editorial workEditorial activity

    Faraday Discussions

    Stuart Alan Macgregor (Invited speaker)
    2 Sep 2019

    Activity: Participating in or organising an eventParticipation in conference

    Access to EPSRC Central facilities

    Stuart Alan Macgregor (Recipient)
    13 Dec 20181 Jun 2021

    Activity: Other

    Organometallic Chemistry in Confined Spaces

    Stuart Alan Macgregor (Speaker)
    6 Sep 2018

    Activity: Talk or presentationInvited talk

    44th International Conference on Coordination Chemistry (ICCC 2020) (Event)

    Stuart Alan Macgregor (Chair)
    1 Nov 201831 Jul 2020

    Activity: MembershipMembership of committee