Structure and reactivity of aryl(bromo)nickel complexes relevant to nickel(0) complex-promoted dehalogenative polycondensation of organic dihalides
- 1 January 1994
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in J. Chem. Soc., Dalton Trans.
- No. 6,p. 943-948
- https://doi.org/10.1039/dt9940000943
Abstract
Reactions of 4-bromobiphenyl, 1,4-dibromobenzene, and 9,10-dibromoanthracene with [Ni(cod)2](cod = cycloocta-1,5-diene) in the presence of PEt3 gave arylnickel complexes, tans-[NiBr(C6H4C6H5)(PEt3)2]1, trans-[NiBr(C6H4Br-p)(PEt3)2]2, and trans-[NiBr(C14H8Br)(PEt3)2]3, respectively. 4,4′-Dibromobiphenyl reacted with a [Ni(cod)2]–PEt3 mixture to give trans, trans-[(Et3P)2BrNi(C6H4C6H4)NiBr(PEt3)2]4. The structures of complexes 1–4 with trans configuration around square-planar nickel centres have been determined by X-ray crystallography. The NMR (1H, 13C, and 31P) spectra of the complexes are consistent with the trans structures. Complexes 2 and trans-[NiBr(Ph)(PEt3)2]5 did not undergo any thermal reaction at 60 °C in dimethylformamide. Complex 2 reacted with Mel at room temperature to give a mixture of p-bromotoluene (17%) and 4,4′-dibromobiphenyl (8%), while similar reaction of 5 gave a mixture of toluene (15%) and biphenyl (78%). Reaction of complex 4 with Mel gave 4-methylbiphenyl and quaterphenyl.Keywords
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