N-Heterocyclic Carbene-Based Nickel Complexes: Synthesis and Catalysis in Cross-Couplings of Aryl Chlorides with ArMX (M = Mg or Zn)
2009; American Chemical Society; Volume: 28; Issue: 22 Linguagem: Inglês
10.1021/om9006399
ISSN1520-6041
Autores Tópico(s)Coordination Chemistry and Organometallics
ResumoTwo C,N,N-chelate nickel complexes, [Ni(Cl){2-(CN(Me)(CH)2N)C6H4N═P(Ph2)CH2Pyr}]+I− and [Ni(Cl){2-(CN(Pri)(CH)2N)C6H4N═P(Ph2)CH2P(Ph2)═NC6H4Me-4}]+I−, were synthesized by reaction of (DME)NiCl2 (DME = 1,2-dimethoxyethane) with 2-(CN(R)(CH)2N)C6H4N═P(Ph2)CH2Z (R = Me, Z = 2-Pyr; R = Pri, Z = p-MeC6H4N═P(Ph2)) ligands, which were prepared in situ by reaction of corresponding imidazolium salts with 1 equiv of LiBun. C,N,P-Chelate nickel complex [Ni(Br){2-(CN(CH2Ph)(CH)2N)C6H4N═P(Ph2)CH2PPh2}]+Br− was obtained by a similar reaction between (DME)NiBr2 and 2-(CN(CH2Ph)(CH)2N)C6H4N═P(Ph2)CH2PPh2 ligand prepared from the imidazolium salt and 1 equiv of LiBun. Tetradentate chelate nickel complex [Ni{2-(CN(CH2Ph)(CH)2N)C6H4N═P(Ph2)}2CH]+Cl− was synthesized by transmetalation between (DME)NiCl2 and [Li{2-(CN(CH2Ph)(CH)2N)C6H4N═P(Ph2)}2CH] generated in situ from [{2-(CHN(CH2Ph)(CH)2N)C6H4N═P(Ph2)}2CH2]2+[Br−]2 and 3 equiv of LiBun. The complexes were characterized by 1H, 13C, and 31P NMR spectroscopy and elemental analyses. The C,N,N-chelate nickel complexes and the tetradentate chelate nickel complex were additionally characterized by single-crystal X-ray diffraction techniques. The complexes are active catalysts for the cross-coupling reactions of aryl chlorides with arylzinc reagents and aryl Grignard reagents.
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