Dipalladium bis(μ-isopropylthiolato) complexes with a [Pd2S2] core supported by N-heterocyclic carbenes

The reaction of Pd(OAc)(2) with 1,3-dibenzylbenzimidazolium bromide (A) and 1-propyl-3-methylbenzimidazolium iodide (B) afforded the dihalo-bis(carbene) complexes cis- [PdBr2(Bz(2)-bimy)(2)] (1) and cis-[PdI2 Pr,Me-bimy)(2)] (2), respectively. Halide substitution of 1 and 2 with AgO2CCH3 gave the mixed diacetato-bis(carbene) complexes cis- [Pd(O2CCH3)(2)(Bz(2)-bimy)(2)] (3) and cis-[Pd(O2CCH3)(2)(Pr,Me-bimy)(2)] (4). In situ deprotonation of isopropylthiol with the mixed carbene-carboxylato complexes 3 and 4 yielded the novel dipalladium complexes [Pd-2(mu-iPr-S)(2)(Bz(2)-bimy)(4)](BF4)(2) (5) and [Pd-2(mu-iPr-S)(2)(Pr,Me-bimy)(4)](BF4)(2) (6) with a [Pd2S2] core solely supported by N-heterocyclic carbenes. All compounds have been fully characterized by multinuclei NMR spectroscopies and ESI mass spectrometry. The solid state molecular structures of complexes 2, 3, 5, and 6 have also been confirmed by X-ray diffraction studies.