Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

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Schaub, T. et al.

Efficient C-F and C-C activation by a novel N-heterocyclic carbene-nickel(0) complex.

The NHC-stabilized complex [Ni(2)(iPr(2)Im)(4)(cod)] (1) was isolated in good yield from the reaction of [Ni(cod)(2)] with 1,3-diisopropylimidazole-2-ylidene (iPr(2)Im). Compound 1 is a source of the [Ni(iPr(2)Im)(2)] complex fragment in stoichiometric and catalytic transformations. The reactions of 1 with ethylene and CO under atmospheric pressure or with equimolar amounts of diphenylacetylene lead to the compounds [Ni(iPr(2)Im)(2)(eta(2)-C(2)H(4))] (2), [Ni(iPr(2)Im)(2)(eta(2)-C(2)Ph(2))] (3), and [Ni(iPr(2)Im)(2)(CO)(2)] (4) in good yields. In all cases the [Ni(iPr(2)Im)(2)] complex fragment is readily transferred without decomposition or fragmentation. In the infrared spectrum of carbonyl complex 4, the CO stretching frequencies are observed at 1847 and 1921 cm(-1), and are significantly shifted to lower wavenumbers compared with other nickel(0) carbonyl complexes of the type [NiL(2)(CO)(2)]. Complex 1 activates the C--F bond of hexafluorobenzene very efficiently to give [Ni(iPr(2)Im)(2)(F)(C(6)F(5))] (5). Furthermore, [Ni(2)(iPr(2)Im)(4)(cod)] (1) is also an excellent catalyst for the catalytic insertion of diphenylacetylene into the 2,2' bond of biphenylene. The reaction of 1 with equimolar amounts of biphenylene at low temperature leads to [Ni(iPr(2)Im)(2)(2,2'-biphenyl)] (6), which is formed by insertion into the strained 2,2' bond. The reaction of diphenylacetylene and biphenylene at 80 degrees C in the presence of 2 mol % of 1 as catalyst yields diphenylphenanthrene quantitatively and is complete within 30 minutes.[1]

References

Efficient C-F and C-C activation by a novel N-heterocyclic carbene-nickel(0) complex. Schaub, T., Radius, U. Chemistry (Weinheim an der Bergstrasse, Germany) (2005) [Pubmed]

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