Bis(1-R-imidazol-2-yl)disulfides, (mimR)2 (R = Ph, But), and diselenides, (seimMes)2, serve as bidentate N,N-donor ligands for main-group and transition metals. For example, [κ2-(mimBut)2]MCl2 (M = Fe, Co, Ni, Zn), [κ2-(mimPh)2]-MCl 2 (M = Co, Zn), [κ2-(mimBut) 2]CuX (X = Cl, I), and [κ2-(seimMes) 2]MCl2 (M = Fe, Co, Ni) are obtained by treatment of (mimBut)2 or (seimMes)2 with the respective metal halide and have been structurally characterized by X-ray diffraction. On the other hand, the zerovalent nickel complex Ni(PMe 3)4 effects cleavage of the disulfide bond of (mim But)2 to give square-planar trans-Ni(PMe3) 2(mimBut)2 in which the (mimBut) ligands coordinate via nitrogen rather than sulfur, a most uncommon coordination mode for this class of ligands. Although [κ2-(mim R)2]MCl2 (M = Fe, Co, Ni, Zn) are not subject to homolytic cleavage of the S-S bond because the tetravalent state is not readily accessible, the observation that [κ2-(mim Ph)2]CoCl2 and [κ2(mim But)2]CoCl2 form an equilibrium mixture with the asymmetric disulfide [κ2-(mimPh)(mim But)]CoCl2 indicates that S-S bond cleavage via another mechanism is possible. Likewise, metathesis between disulfide and diselenide ligands is observed in the formation of [κ2-(mim But)(seimMes)]-CoCl2 upon treatment of [κ2-(mimBut)2]CoCl2 with [κ2-(seimMes)2]CoCl2.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry