Preparation of Iodide-Thiolate Bridged Binuclear Ni-Ni Complexes via Versatile Reaction of Labile Ni(II)-S(thiolate) Bond

Abstract

The reaction between Fe(CO)4I2and Ni(SR)2(dppe) affords NiI2(dppe) due to the nucleophilic attack of iodide on the labile Ni-S(thiolate) bonds. The iodide-dithiolate-bridged binuclear Ni-Ni complexes [(dppe)Ni(µ-I)(µ-pdt)Ni(dppe)]I is readily prepared from the reaction between [NiI2(dppe)] and [Ni(pdt)(dppe)] [dppe = 1,2-bis(diphenyl phosphino)-ethane; pdt = 1,3-propane-dithiolate] in CH2Cl2as a result of attack on Ni-I bond by the lone pairs of electrons on thiolato sulfur donors. The reaction between [FeCp(CO)2I] and [Ni(pdt)(dppe)] in CH2Cl2processes extremely slowly. However, upon metathesis with NH4PF6, the iodide-thiolate bridged binuclear Ni-Ni complexes [(dppe)Ni(µ-I)(µ-pdt)Ni(dppe)]PF6is formed from the reaction of iodide and the Ni(II)-S bonds. The reaction between [NiCl2(dppe)] and NH4PF6and [Ni(pdt)(dppe)] gives a binuclear complex [(dppe)Ni(µ-pdt)Ni(dppe)]PF6without a halide-bridge. These results suggest that the reactivity of Ni-SR bonds in the Ni-thiolate-phosphine complexes is tunable with regard to the electronic environment of second metal ion and the different reactivity of iodide moiety. Electrochemical and crystallographic results are also analyzed for relevant compounds.