Synthesis, Structure, and Reactivity of Pd Complexes with Mixed P,S‐Bis(ylide), Ylide–Sulfide, and Ylide–Methanide Ligands

The coordination properties of the ylide–sulfonium salts [Ph 3 P=C(H)COCH 2 S(R 1 )R 2 ]X [R 1 = R 2 = Et, X = Br ( 2 ); R 1 = Me, R 2 = Ph, X = ClO 4 ( 5 )], the phosphonium–sulfide salt [Ph 3 PCH 2 COCH 2 SEt]Br ( 3 ) and the neutral ylide–sulfide [Ph 3 P=C(H)COCH 2 SPh] ( 4 ) towards Pd II have been studied. Four different bonding modes have been characterized. The reactions of the ylide–sulfonium salts 2 and 5 with PdCl 2 (NCMe) 2 and NEt 3 afford the chelating bis(ylide) complexes cis ‐[PdCl 2 {Ph 3 PC(H)COC(H)S(R 1 )R 2 ‐κ C , C }] [R 1 = R 2 = Et ( 6 ); R 1 = Me, R 2 = Ph ( 7 )], which are obtained selectively in the meso form ( RS / SR ). This bonding mode is characterized, including by X‐ray crystallography, in the acetylacetonate (acac) complexes [Pd(acac‐ O , O′ ){Ph 3 PC(H)COC(H)S(R 1 )R 2 ‐κ C , C }]ClO 4 [R 1 = R 2 = Et ( 8 ); R 1 = Me, R 2 = Ph ( 9 )], which were obtained by reaction of the respective precursor 6 or 7 with AgClO 4 and Tl(acac). On the other hand, the C , S ‐chelating bonding mode has been characterized in [PdCl 2 {Ph 3 PC(H)COCH 2 SR‐κ C , S }] [R = Et ( 10 ); R = Ph ( 11 )], obtained by reaction of the phosphonium–sulfide salt 3 with PdCl 2 (NCMe) 2 and NEt 3 or by reaction of the ylide–sulfide 4 with PdCl 2 (NCMe) 2 , respectively. Furthermore, the tridentate bonding mode μ‐ S :κ C , C , S has been determined in the dinuclear derivative [PdCl{Ph 3 PC(H)COC(H)SPh‐μ‐ S :κ C , C ,S}] 2 ( 13 ), synthesized by reaction of the ylide–sulfide 4 with PdCl 2 (NCMe) 2 and NEt 3 . Compound 13 reacts with PPh 3 to afford the κ C , C ‐chelate [PdCl{Ph 3 PC(H)COC(H)SPh‐κ C ,C}PPh 3 ] ( 14 ) after cleavage of the sulfide bridge. Compound 14 was obtained as a single diastereoisomer, which was characterized as the D , L form ( RR / SS ).