Reactivity and stability of a ring-expanded N-heterocyclic carbene copper(I) boryl imidinate

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Charman, Rex S. C. and Horsley Downie, Thomas M. and Jerome, Thomas H. and Mahon, Mary F. and Liptrot, David J. (2022) Reactivity and stability of a ring-expanded N-heterocyclic carbene copper(I) boryl imidinate. Inorganics, 10 (9). 135. ISSN 2304-6740 (https://doi.org/10.3390/inorganics10090135)

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Abstract

Frustrated Lewis pairs (FLPs) have evolved from a revolutionary concept to widely applied catalysts. We recently reported the ring-expanded N-heterocyclic carbene supported copper(I) boryliminomethanide, (6-Dipp)CuC(=NtBu)Bpin and noted it reacted with heterocumulenes in a fashion reminiscent of FLPs. We thus set out to explore its reactivity with a range of other substrates known to react with FLPs. This was undertaken by a series of synthetic studies using NMR spectroscopy, mass spectrometry, IR spectroscopy, and single crystal X-ray crystallography. (6-Dipp)CuC(=NtBu)Bpin was investigated for its reactivity towards water, hydrogen, and phenylacetylene. Its solution stability was also explored. Upon heating, (6-Dipp)CuC(=NtBu)Bpin decomposed to (6-Dipp)CuCN, which was characterised by SC-XRD and NMR spectroscopy, and pinBtBu. Although no reaction was observed with hydrogen, (6-Dipp)CuC(=NtBu)Bpin reacted with water to form (6-Dipp)CuC(=N(H)tBu)B(OH)pin, which was structurally characterised. In contrast to its FLP-reminiscent heterolytic cleavage reactivity towards water, (6-Dipp)CuC(=NtBu)Bpin acted as a Brønsted base towards phenyl acetylene generating (6-Dipp)CuCCPh, which was characterised by SC-XRD, IR, and NMR spectroscopy, and HC(=NtBu)Bpin

ORCID iDs

Charman, Rex S. C., Horsley Downie, Thomas M. ORCID logoORCID: https://orcid.org/0000-0001-5027-450X, Jerome, Thomas H., Mahon, Mary F. and Liptrot, David J.;
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