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

Treatment of 1,2,4,5-( t BuSCH 2 ) 4 C 6 H 2 with K 2 PdCl 4 /NaOAc in ethanol yielded only the monopalladated complex [PdCl(( t BuSCH 2 ) 4 C 6 H)] regardless of whether 1 or 2 equiv of K 2 PdCl 4 is used. Alternately, the reaction of 1,2,4,5-( t BuSCH 2 ) 4 C 6 H 2 with 1 or 2 equiv of [Pd(MeCN) 4 ][BF 4 ] 2 in MeCN resulted in quantitative production of the dipalladated species [Pd 2 (( t BuSCH 2 ) 4 C 6 )(MeCN) 2 ][BF 4 ] 2 based on palladium starting material. The X-ray structures of the two products [PdCl(( t BuSCH 2 ) 4 C 6 H)] and [Pd 2 (( t BuSCH 2 ) 4 C 6 )(MeCN) 2 ][BF 4 ] 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.