名称:
Mono- versus Dipalladation of the Durene-Based Tetrathioether Ligand 1,2,4,5-(tBuSCH2)4C6H2. Structures of [PdCl((tBuSCH2)4C6H)] and [Pd2((tBuSCH2)4C6)(MeCN)2][BF4]2
摘要:
Treatment of 1,2,4,5-(tBuSCH(2))(4)C6H2 with K2PdCl4/NaOAc in ethanol yielded only the monopalladated complex [PdCl((tBuSCH(2))(4)C6H)] regardless of whether 1 or 2 equiv of K2PdCl4 is used. Alternately, the reaction of 1,2,4,5-(tBuSCH(2))(4)C6H2 with 1 Or 2 equiv of [Pd(MeCN)(4)][BF4](2) in MeCN resulted in quantitative production of the dipalladated species [Pd-2((tBuSCH(2))(4)C-6)(MeCN)(2)][BF4](2) based on palladium starting material. The X-ray structures of the two products [PdCl((tBuSCH(2))(4)C6H)] and [Pd-2((tBuSCH(2))(4)C-6)(MeCN)(2)][BF4](2) are reported. MO calculations were consistent with the idea that the ligand trans to the first Pd-C bond dictates the electrophilic aromatic substitution pattern and determines whether a second palladation will occur. Thus, Pd-Cl is deactivating while (Pd-MeCN)(+) is activating, resulting in the formation of exclusively mono- and dipalladated products, respectively.