Different bonding modes of sulfur bis-ylides in Pd complexes: Crystal structure of [Pd(μ-OAc){μ-[CH(SMe 2)] 2C(O)}(acac-O,O′) 2]ClO 4

Abstract

The reaction of [Me 2SCH 2C(O)CH 2SMe 2]Br 2 ( 1) with Pd(OAc) 2 gives the mononuclear neutral complex cis-[PdBr 2{η 2-[CH(SMe 2)] 2C(O)}] ( 2) through double deprotonation of the bis-sulfonium salt. The sulfur bis-ylide coordinates in ( 2) as a C,C′-chelating ligand, and is obtained as a single diastereoisomer ( meso form, RS/ SR), in spite of the presence of two stereogenic ylidic centers. Reaction of ( 2) with AgClO 4 and Tlacac gives [Pd(acac-O,O′){η 2-[CH(SMe 2)] 2C(O)}]ClO 4 ( 3), which shows the same bonding mode for the bis-ylide ligand. However, ( 2) reacts with Pd(OAc) 2, AgClO 4 and Tlacac to give the dinuclear [Pd(μ-OAc){μ-[CH(SMe 2)] 2C(O)}(acac-O,O′) 2]ClO 4 ( 4) as two different isomers. In complex ( 4) the bis-ylide bridges two palladium atoms and the presence of two isomers arise from the relative arrangement of the bis-ylide with respect to the acetate ligand. The X-ray crystal structure of ( 4) has been determined.