NHC‐Stabilized Nickel Olefin, Dialkyl, and Dicyanido Complexes

• Published in: European journal of inorganic chemistry 2019-07, Vol.2019 (26), p.3061-3072
• Main Authors: Berthel, Johannes H. J., Tendera, Lukas, Kuntze‐Fechner, Maximilian W., Kuehn, Laura, Radius, Udo
• Format: Article
• Language: English
• Subjects: Alkyl complexes; Alkyne complexes; Alkynes; Carbene ligands; Cyanides; Cyanido complexes; Inorganic chemistry; Nickel; Olefin complexes; Reduction (metal working); Synthesis
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201900484

The complexes trans‐[Ni(iPr2Im)2Br2] 1, trans‐[Ni(iPr2ImMe)2Br2] 2, trans‐[Ni(Me2Im)2I2] 3, and trans‐[Ni(Me2ImMe)2Br2] 4 (R2Im = 1,3‐diorganyl‐imidazolin‐2‐ylidene, R2ImMe = 1,3‐diorganyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene) are useful precursor for the synthesis of NHC‐stabilized nickel olefin, alkyne, alkyl and cyanido complexes. [Ni(NHC)2(η2‐olefin)] and [Ni(NHC)2(η2‐alkyne)] can be prepared via metallic reduction in the presence of the olefin or alkyne, as exemplified by the synthesis of [Ni(Me2Im)2(η2‐C2H4)] 5, [Ni(Me2Im)2(η2‐C2Me2)] 6, [Ni(Me2Im)2(η2‐COE)] 7 and [Ni(Me2ImMe)2(η2‐COE)] 8 (COE = cyclooctene). The reaction of trans‐[Ni(iPr2ImMe)2Br2] 2 with MeMgCl, EtMgBr or nBuLi leads to trans‐[Ni(iPr2ImMe)2(CH3)2] 9, trans‐[Ni(iPr2ImMe)2(C2H5)2] 10 and trans‐[Ni(iPr2ImMe)2(n‐C4H9)2] 11. The reaction of 2 with iPrMgBr afforded minor amounts of [Ni(iPr2ImMe)2(η2‐H2C=CHCH3)] 12. Dicyanido complexes trans‐[Ni(iPr2Im)2(CN)2] 13, trans‐[Ni(iPr2ImMe)2(CN)2] 14, trans‐[Ni(Me2Im)2(CN)2] 15, and trans‐[Ni(Me2ImMe)2(CN)2] 16 were prepared from reaction of the dihalide complexes 1–4 and trimethylsilyl cyanide. The synthesis of different NHC‐stabilized nickel olefin, alkyne, alkyl, and cyanido complexes is reported starting from trans‐[Ni(iPr2Im)2Br2], trans‐[Ni(iPr2ImMe)2Br2], trans‐[Ni(Me2Im)2I2], and trans‐[Ni(Me2ImMe)2Br2] (R2Im = 1,3‐diorganyl‐imidazolin‐2‐ylidene, R2ImMe = 1,3‐diorganyl‐4,5‐dimethyl‐imidazolin‐2‐ylidene) as synthetically useful nickel (II) precursors.