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Teaching an old dog new tricks – early transition metal PCP and POCOP complexes

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Location: PLT

Dr F. Mark Chadwick join us from the Department of Chemistry, Imperial College London to deliver this guest seminar. Everyone is welcome. Refreshments will be served outside PLT before the talk.

Teaching an old dog new tricks – early transition metal PCP and POCOP complexes

F. Mark Chadwick Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, W12 0BZ, UK m.chadwick@imperial.ac.uk

Pincer complexes hold a privileged place in organometallic chemistry. Arguably the most recognisable is the original ‘PCP’ framework discovered by Shaw in 1976.1 However, most of the work carried out with these pincer ligands has used the late transition metals. A reason for this is that the usual synthetic route requires oxidative addition and that can be problematic for early transition metals (due to the lack of suitable low valent synthons). This research has developed an alternative synthesis for early transition metal PCP and POCOP complexes. By using a halogenated precursor we can perform lithium/halogen exchange. This produces an entry point synthon for the ligands’ deployment on both the s-block and early transition metals. We have used this to make a range of Ti, Cr and Ca complexes.2 With titanium the synthon reduces Ti(IV) to Ti(III). The metal complexes can be derivatised and characterised, including by EPR spectroscopy (in the case of Ti(III) and Cr). Their reactivity with small molecules has also been explored.

References: 

1) Moulton, C. J., Shaw, B. L., J. Chem. Soc., Dalton Trans., 1976, 1020-1024;

2) Webster, L., Krämer, T., Chadwick, F. M., Dalton Trans., 2022, 51, 16714-16722; Stadler, B., Meng, H. H. Y., Belazregue, S.,

Webster, L., Collauto, A., Byrne, K. M., Kramer, T., Chadwick, F. M., Organometallics, 2023, DOI:

10.1012/acs.organomet.2c00662

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