Accessing the (CpNi)-Ni-Ar(I) Synthon: Reactions with N-Heterocyclic Carbenes, TEMPO, Sulfur, and Selenium

作者：Chakraborty Uttam; Urban Franziska; Muehldorft Bernd; Rebreyend Christophe; de Bruin Bas; van Velzen Niels; Harder Sjoerd; Wolf Robert

来源：Organometallics, 2016, 35(11): 1624-1631.

DOI：10.1021/acs.organomet.6b00084

A reactive "(CpNiI)-Ni-Ar" surrogate (Cp-Ar = C-5(C6H4-4-Et)(5)) is accessible via the reduction of the dimer [(CpNi)-Ni-Ar(mu-Br)](2) with two equivalents of KC8. A trapping reaction with TEMPO afforded the new nickel(II) complex [(CpNi)-Ni-Ar(eta(2)-TEMPO)] (3), while the addition of N-heterocyclic carbenes gave the new nickel(I) radicals [(CpNi)-Ni-Ar(IPr)] (4a, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) and [(CpNi)-Ni-Ar(IiPr(2)Me(2))] (4b, IiPr(2)Me(2) = 1,3-diisopropy1-4,5-dimethylimidazol-2-ylidene). EPR spectra supported by DFT calculations on 4a and 4b indicate that the spin density mainly resides at the nickel center. The reaction of the "(CpNi)-Ni-Ar(I) source" with yellow sulfur gave the Ni2S6 complex [((CpNi)-Ni-Ar)(2)(mu-S-6)] (5); the "subselenide" [((CpNi)-Ni-Ar)(2)(mu-Se-2)] (6) was formed in the analogous reaction with grey selenium. All new complexes were characterized by NMR, EPR, and UV-vis spectroscopy; their molecular structures were determined by X-ray crystallography.

• 出版日期2016-6-13