Ring‐Expanded N‐Heterocyclic Copper(I) Boryl Complexes: The Structures of [(6‐Dipp)CuBcat], [(6‐Dipp)CuBneop], and [(6‐Dipp)CuBhex]

σ‐Bond metathesis reactions between [(6‐Dipp)CuOtBu] (6‐Dipp=:C({Dipp}NCH2)2CH2, Dipp=2,6‐iPr2−C6H3) and three diboranes gave access to three new copper(I) boryl complexes [(6‐Dipp)CuBcat], [(6‐Dipp)CuBneop], and [(6‐Dipp)CuBhex] (cat=1,2‐O2C6H4; neop=(OCH2)2C(CH3)2; hex=OC(CH3)HCH2C(CH3)2O). Whilst...

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Published inEuropean journal of inorganic chemistry Vol. 26; no. 13
Main Authors Babula, Dawid J., Charman, Rex S. C., Jerome, Thomas H., Horsley Downie, Thomas M., Mahon, Mary F., Liptrot, David J.
Format Journal Article
LanguageEnglish
Published Weinheim Wiley Subscription Services, Inc 02.05.2023
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Summary:σ‐Bond metathesis reactions between [(6‐Dipp)CuOtBu] (6‐Dipp=:C({Dipp}NCH2)2CH2, Dipp=2,6‐iPr2−C6H3) and three diboranes gave access to three new copper(I) boryl complexes [(6‐Dipp)CuBcat], [(6‐Dipp)CuBneop], and [(6‐Dipp)CuBhex] (cat=1,2‐O2C6H4; neop=(OCH2)2C(CH3)2; hex=OC(CH3)HCH2C(CH3)2O). Whilst [(6‐Dipp)CuBcat] and [(6‐Dipp)CuBneop] formed rapidly in toluene, access to [(6‐Dipp)CuBhex] required heating to 60 °C for days. The complexes were characterised by single‐crystal X‐ray crystallography which showed in all three cases that the systems were monomers and distorted‐linear at the copper atom. The stability of [(6‐Dipp)CuBneop] was found to be comparable to that of [(IPr*)Cu‐Bneop] (IPr*=1,3‐bis(2,6‐(diphenylmethyl)‐4‐methylphenyl)imidazol‐2‐ylidene); it persisted in solution for days with no sign of decomposition. [(6‐Dipp)CuBhex] is a rare crystallographically characterised example of a complex containing a boryl anion supported by the hexylene glycolato ligand. A ring‐expanded NHC with flanking di‐iso‐propylphenyl groups has been shown to support 3 copper(I) boryl systems. This allows the structural characterisation of [(6‐Dipp)CuBcat], [(6‐Dipp)CuBneop], and [(6‐Dipp)CuBhex] (cat=1,2‐O2C6H4; neop=(OCH2)2CMe2; hex=OC(CH3)HCH2C(CH3)2O). All three compounds are reasonably stable, readily isolable sources of boryl nucleophiles, and [(6‐Dipp)CuBhex] is a rare example of a boryl anion bearing the hexylene glycol ester.
ISSN:1434-1948
1099-0682
DOI:10.1002/ejic.202300043