Facile C-S, S-H, and S-S bond cleavage using a nickel(0) NHC complex.Dalton Trans. 2009 Sep 21DT
[Ni2(iPr2Im)4(COD)] 1 (iPr2Im = 1,3-di(isopropyl)-imidazol-2-ylidene) reacts at room temperature with the thioethers methyl para-tolyl sulfide, ethyl phenyl sulfide, benzothiophene and dibenzothiophene to afford the C-S bond cleavage products [Ni(iPr2Im)2(4-CH3-C6H4)(SMe)] 2, [Ni(iPr2Im)2(C6H5)(SEt)] 3, [Ni(iPr2Im)2(1,8-benzothiophenylato)] 4 and [Ni(iPr2Im)2(C,S-dibenzothiophenylato)] 5. In contrast to the reaction of thioethers or sulfoxides (reported earlier), no C-S bond cleavage was observed for the reaction of 1 with the sulfones bezothiophene-1,1-dioxide and methyl phenyl sulfone. In those cases the stable compounds [Ni(iPr2Im)2(eta2-2,3-benzothiophene-1,1-dioxide)] 6 and [Ni(iPr2Im)2(eta2-MeSO2C6H5)] 7 with a eta2-coordinated sulfone ligand have been isolated. Compound 6 has been structurally characterized. S-H bond cleavage was observed using 2-methyl-2-propanthiol to afford [Ni(iPr2Im)2(H)(StBu)] 8. The reaction of 1 with disulfides led to the dithiolato complexes [Ni(iPr2Im)2(SR)2] (R = tBu 9, Me 10, Ph 11) by S-S bond scission.