Gold(I) and Palladium(II) Complexes Containing the Functionalized Ylides Triarylphosphonium Cyanomethylide or 2-Cyanoethylide (R3P=CHR′, R′=CN,CH2CN)

The coordination properties of ylides R₃P=CHCN and R₃P=CHCH₂CN were studied. Ylide R₃P=CHCN reacts with AuCl(tht)] (molar ratio 1 : 1, tht=tetrahydrothiophene) to give AuCl{CH(PPh₃)CN}] ( 1 ). Dinuclear complexes (AuL)₂{μ-C(PR₃)CN}]ClO₄?nH₂O (n=1, L=PPh₃, R=Ph ( 2a ) or Tol (=4-MeC₆H₄) ( 2b ); n=0, R=Tol, L=P(pmp)₃ ( 2c ; pmp=4-MeOC₆H₄ or AsPh₃ ( 2d )) are the products of reactions between phosphonium salts (R₃PCH₂CN)ClO₄ (R=Ph or Tol) and Au(acac)L] (molar ratio 1 : 3, L=PPh₃ or P(pmp)₃; acacH=acetylacetone). The reaction of Au(acac)PPh₃] with (Ph₃PCH₂CH₂CN)ClO₄ (Au/P 2 – 5) gives the mononuclear complex Au{CH(PPh₃)CH₂CN}(PPh₃)]ClO₄?0.5 H₂O ( 3 ). Complexes 2b or 2c react with Au(acetone)L]ClO₄ (molar ratio 1 : 1, L=PPh₃ or P(pmp)₃), prepared in situ from AuCl(L)] and AgClO₄ in acetone, to give the corresponding trinuclear derivatives (AuL)₂{μ₃-{C(PTol₃)CN}(AuL)}](ClO₄)₂ (L=PPh₃ ( 4a ) or P(pmp)₃ ( 4b )]. We attempted unsuccessfully to prepare single crystals of 4a or 4b or of the triflate salt {Au(PPh₃)}₂{μ₃-{C(PTol₃)CN}(AuPPh₃)}](TfO)₂?H₂O ( 4a′ ), obtained by reacting 4a with 2 equiv. of KCF₃SO₃. In complexes 2 and 4 , two new types of coordination of the ylides R₃P=CHCN are present. Attempts to coordinate three AuL groups to the N-atom of (R₃PCCN)^? induced by aurophilicity (see A and B ) were unsuccessful. The reaction between PdCl₂ and R₃P=CHCN (molar ratio 1 : 2) gives trans-PdCl₂{CH(PTol₃)CN}₂] ( 5 ).