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

摘要

The coordination properties of the ylide-sulfonium salts[Ph_3P=C(H)COCH_2S(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_3PCH_2COCH_2SEt]Br (3) and the neutral ylide-sulfide[Ph_3P=C(H)COCH_2SPh] (4) towards PdII 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_3PC(H)COC(H)S(R~1)R~2-κC,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_3PC(H)COC(H)S(R~1)R~2- κC,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,Schelating bonding mode has been characterized in[PdCl_2{Ph_3PC(H)COCH_2SR-κC,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:κC,C,S has been determined in the dinuclear derivative [PdCl{Ph_3PC(H)COC(H)SPh-μ- S:κC,C,S}]_2 (13), synthesized by reaction of the ylide-sulfide4 with PdCl_2(NCMe)_2 and NEt_3. Compound 13 reacts with PPh_3 to afford the κC,C-chelate [PdCl{Ph_3PC(H)COC(H)SPh- κC,C}PPh_3] (14) after cleavage of the sulfide bridge. Compound14 was obtained as a single diastereoisomer, which was characterized as the D,L form (RR/SS).