Past research highlights

In collaboration with Mercedes Alonso, we have critically assessed the role of electrostatics in metal carbonyl bonds. Our work highlights limitations in the Dewar–Chatt–Duncanson bonding paradigm and helps rationalise the existence of non-classical carbonyl complexes (examples where ν(CO) > 2143 cm^-1).

• G. L. Parker, R. Van Lommel, N. Roig, M. Alonso* and A. B. Chaplin*. Modulation of Metal Carbonyl Stretching Frequencies in the Second Coordination Sphere through the Internal Stark Effect. Chem. Eur. J. 2022, 28, e202202283Link opens in a new window.
• N. Roig, R. Van Lommel, M. Alonso* and A. B. Chaplin*. Deconvoluting the Role of Electrostatics in Metal Carbonyl Bonding: Dipole Moments and Energy Decomposition Analysis of Late Transition Metal Pincer Complexes. Organometallics 2024, 43, 2787–2796Link opens in a new window.
• N. Roig, M. Alonso* and A. B. Chaplin*. Vibrational solvatochromism of rhodium pybox carbonyl complexes mediated by hydrogen bonding. Chem. Commun. 2026, 62, 13107–13109Link opens in a new window.

[for earlier work on the use of Rh(CO) as a reporter group see Eur. J. Inorg. Chem. 2019Link opens in a new window]

• T. M. Hood, M. R. Gyton and A. B. Chaplin*. Synthesis and rhodium complexes of macrocyclic PNP and PONOP pincer ligands. Dalton Trans. 2020, 49, 2077–2086Link opens in a new window.
  
• B. Leforestier, M. R. Gyton and A. B. Chaplin*. Synthesis and group 9 complexes of macrocyclic PCP and POCOP pincer ligands. Dalton Trans. 2020, 49, 2087–2101Link opens in a new window.
  
• B. Leforestier, M. R. Gyton and A. B. Chaplin*. Oxidative addition of a mechanically entrapped C(sp)–C(sp) bond to a rhodium(I) pincer complex. Angew. Chem. Int. Ed. 2020, 59, 23500–23504Link opens in a new window.
  
• T. M. Hood and A. B. Chaplin*. Reactions of Rh(PNP) pincer complexes with terminal alkynes: homocoupling through a ring or not at all. Dalton Trans. 2020, 49, 16649–16652.Link opens in a new window
  
• T. M. Hood and A. B. Chaplin*. Synthesis and reactivity of iridium complexes of a macrocyclic PNP pincer ligand. Dalton Trans. 2021, 50, 2472–2482.
  
• T. M. Hood,* S. Lau and A. B. Chaplin*. Capture of mechanically interlocked molecules by rhodium-mediated terminal alkyne dimerisation. RSC Adv. 2024, 14, 7740–7744Link opens in a new window.
  

• R. E. Andrew and A. B. Chaplin*. Synthesis, structure and dynamics of NHC-based palladium macrocycles. Dalton Trans. 2014, 43, 1413–1423Link opens in a new window.
  
• R. E. Andrew and A. B. Chaplin*. Synthesis and reactivity of NHC-based rhodium macrocycles. Inorg. Chem. 2015, 54, 312–322Link opens in a new window.
  
• R. E. Andrew, D. W. Ferdani, C. A. Ohlin and A. B. Chaplin*. Coordination Induced Atropisomerism in an NHC-based Rhodium Macrocycle. Organometallics 2015, 53, 913–917Link opens in a new window.
  
• R. E. Andrew, C. M. Storey and A. B. Chaplin*. Well-defined coinage metal transfer agents for the synthesis of NHC-based nickel, rhodium and palladium macrocycles. Dalton Trans. 2016, 45, 8937–8944Link opens in a new window.
  
• S. L. Apps, R. E. Alflatt, B. Leforestier, C. M. Storey* and A. B. Chaplin*. Divergent stereoisomers of molybdenum carbonyl complexes of NHC-based pincer ligands. Polyhedron 2018, 143, 57–61Link opens in a new window.
  
• C. M. Storey, M. R. Gyton, R. E. Andrew and A. B. Chaplin*. Terminal Alkyne Coupling Reactions through a Ring: Mechanistic Insights and Regiochemical Switching. Angew. Chem. Int. Ed. 2018, 57, 12003–12006Link opens in a new window.
  
• M. R. Gyton, B. Leforestier and A. B. Chaplin*. Rhodium(III) and Iridium(III) Complexes of a NHC-Based Macrocycle: Persistent Weak Agostic Interactions and Reactions with Dihydrogen. Organometallics 2018, 37, 3963–3971Link opens in a new window.
  
• G. M. Parker, S. Lau,* B. Leforestier and A. B. Chaplin*. Probing the Donor Properties of Pincer Ligands Using Rhodium Carbonyl Fragments: An Experimental and Computational Case Study. Eur. J. Inorg. Chem. 2019, 3791–3798Link opens in a new window.
  
• C. M. Storey, M. R. Gyton, R. E. Andrew and A. B. Chaplin*. Terminal Alkyne Coupling Reactions Through a Ring: Effect of Ring Size on Rate and Regioselectivity. Chem. Eur. J. 2020, 26, 14715–17723Link opens in a new window.
  

The high trans influence 2,2′-biphenyl ancillary ligand has been harnessed to study the stabilisation of low-coordinate rhodium(III) and iridium(III) complexes through formation of weak interactions with C–H/C–F bonds, solvents, AgCl, and N₂. Elaboration of a structural motif accessed from the oxidative addition of biphenylene (Organometallics 1995Link opens in a new window, 2001Link opens in a new window, and 2010Link opens in a new window).

• R. C. Knighton, J. Emerson-King, J. P. Rourke, C. A. Ohlin and A. B. Chaplin*. Solution, Solid-State, and Computational Analysis of Agostic Interactions in a Coherent Set of Low-Coordinate Rhodium(III) and Iridium(III) Complexes. Chem. Eur. J. 2018, 24, 4927–4938Link opens in a new window.
  
• M. R. Gyton, B. Leforestier and A. B. Chaplin*. Rhodium(III) and Iridium(III) Complexes of a NHC-Based Macrocycle: Persistent Weak Agostic Interactions and Reactions with Dihydrogen. Organometallics 2018, 37, 3963–3971Link opens in a new window.
  
• J. Emerson-King, I. Prokes and A. B. Chaplin*. Rhodium(III) Complexes Featuring Coordinated CF₃ Appendages. Chem. Eur. J. 2019, 25, 6317–6319Link opens in a new window.
  
• T. M. Hood, B. Leforestier, M. R. Gyton and A. B. Chaplin*. Synthesis and Structural Dynamics of Five-Coordinate Rh(III) and Ir(III) PNP and PONOP Pincer Complexes. Inorg. Chem. 2019, 58, 7593–7601Link opens in a new window.
  
• T. M. Hood, M. R. Gyton and A. B. Chaplin*. Synthesis and rhodium complexes of macrocyclic PNP and PONOP pincer ligands. Dalton Trans. 2020, 49, 2077–2086Link opens in a new window.
  
• M. R. Gyton, A. E. Kynman, B. Leforestier, A. Gallo, J. R. Lewandowski and A. B. Chaplin*. Isolation and structural characterisation of rhodium(III) η²–fluoroarene complexes: experimental verification of predicted regioselectivity. Dalton Trans. 2020, 49, 5791–5793Link opens in a new window.
  
• A. E. Kynman, S. Lau, S. O. Dowd, T. Krämer* and A. B. Chaplin*. Oxidative Addition of Biphenylene and Chlorobenzene to a Rh(CNC) Complex. Eur. J. Inorg. Chem. 2020, 3899–3906 Link opens in a new window.
  
• T. M. Hood and A. B. Chaplin*. Synthesis and reactivity of iridium complexes of a macrocyclic PNP pincer ligand. Dalton Trans. 2021, 50, 2472–2482Link opens in a new window.
  
• W. Poole, I. Bustos, T. M. Hood, J. E. Smart and A. B. Chaplin*. Iridium complexes of an ortho-trifluoromethylphenyl substituted PONOP pincer ligand. Dalton Trans. 2023, 52, 1096–1104Link opens in a new window.
  
• J. Emerson-King, S. Pan, M. R. Gyton, R. Tonner-Zech and A. B. Chaplin*. Synthesis of a rhodium(III) dinitrogen complex using a calix[4]arene-based diphosphine ligand. Chem. Commun. 2023, 59, 2150–2152Link opens in a new window.
  
• J. Emerson-King and A. B. Chaplin*. Template synthesis of an intermediate in silver salt metathesis using a calix[4]arene-based diphosphine ligand. Dalton Trans. 2023, 52, 5044–5046Link opens in a new window.
  
• J. E. Smart, I. Prokes, B. Leforestier* and A. B. Chaplin*. Rhodium(III) and Iridium(III) Complexes of a Neopentyl-substituted PNP Pincer Ligand that Feature Agostic Interactions. Organometallics 2024, 43, 1143–1154Link opens in a new window.
  

We have prepared rhodium and iridium complexes of Glorius’Link opens in a new window conformationally rigid bioxazoline-derived NHC ligands and studied their reactivity. These ligands enable: the isolation of authentic three-coordinate rhodium(I) complexes, the selective and reversible C–H bond activation of fluorobenzenes, and the isolation of complexes with unusually distorted NHC coordination geometries. We also noted the ability of these carbenes to undergo C–F bond activation reactions.

• A. B. Chaplin*. Rhodium(I) Complexes of the Conformationally Rigid IBioxMe₄ Ligand: Isolation of a Stable Low-Coordinate T-Shaped Complex. Organometallics 2014, 33, 624–626Link opens in a new window.
  
• A. B. Chaplin*. Rhodium(I) Complexes of the Conformationally Rigid IBioxMe₄ Ligand: Preparation of Mono-, Bis- and Tris-ligated NHC Complexes. Organometallics 2014, 33, 3069–3077Link opens in a new window
  
• S. A. Hauser, I. Prokes and A. B. Chaplin*. Low-coordinate iridium NHC complexes derived from selective and reversible C–H bond activation of fluoroarenes. Chem. Commun. 2015, 51, 4425–4428Link opens in a new window.
  
• S. A. Hauser, R. Tonner and A. B. Chaplin*. Iridium Complexes of the Conformationally Rigid IBioxMe₄ Ligand: Hydride Complexes and Dehydrogenation of Cyclooctene. Organometallics 2015, 34, 4419–4427Link opens in a new window.
  
• J.-N. Luy, S. A. Hauser, A. B. Chaplin* and R. Tonner*. Rhodium(I) and Iridium(I) Complexes of the Conformationally Rigid IBioxMe₄ Ligand: Computational and Experimental Studies of Unusually Tilted NHC Coordination Geometries. Organometallics 2015, 34, 5099–5112Link opens in a new window.
  
• J. Emerson-King, S. A. Hauser and A. B. Chaplin*. C–F bond activation of perfluorinated arenes by a bioxazoline-derived N-heterocyclic carbene. Org. Biomol. Chem. 2017, 15, 787–789Link opens in a new window.
  

• The development and mechanistic investigation of bench–stable rhodium(I) catalysts, containing the small–bite angle diphosphine ligands for the efficient intermolecular hydroacylation of a wide variety of un-activated alkenes and alkynes with β-S-substituted aldehydes (J. Am. Chem. Soc. 2012Link opens in a new window).

• The activation of C–C and C–H bonds using low coordinate rhodium phosphine complexes. Examples include: the isolation of agostic intermediates in alkyl dehydrogenation (Chem. Commun. 2009Link opens in a new window), reversible C–C bond activation (J. Am. Chem. Soc. 2011Link opens in a new window), and C–C bond activation of biphenylene (Organometallics 2010Link opens in a new window).

• Insights into the mechanism of rhodium catalyzed dehydrocoupling of amine–boranes. In particular the characterisation of B–H bond activation products (Angew. Chem. Int. Ed. 2010Link opens in a new window) and amine–borane sigma complexes (Inorg. Chem. 2010Link opens in a new window).

• The development and mechanism of robust (Inorg. Chem. 2008Link opens in a new window) and chemoselective (Organometallics 2007Link opens in a new window) ruthenium hydrogenation catalysts.

• Inspired by undergraduate material taught at Massy University, alternative bonding models for phosphazenes were critically examined using computational methods (Inorg. Chem. 2005Link opens in a new window).