Isabel C. Barco, Larry R. Falvello, Susana Fernández, Rafael Navarro and Esteban P. Urriolabeitia
The reactivity of the ylide Ph3PC(H)CONMe2 towards different palladium(II) complexes has been explored. Reaction with the cationic solvated complexes [Pd(dmba)(NCMe)2]A, [Pd(R-dmphea)(NCMe)2]A and [Pd(dmba)(py)(thf
)]A (dmba = C6H4CH2NMe2-2; R-dmphea = R-C6H4CHMeNMe2-2; py = pyridine; A = ClO4–) resulted in the formation of [Pd(dmba)(OH2){CH(CONMe2)(PPh3)}]A 1, [Pd(R-dmphea)(OH2){CH(CONMe2)(PPh3)}]A 2, and [Pd(dmba)(py){CH(CONMe2)(PPh3)}]A 3 respectively, in which the ylide is co-ordinated through its carbon atom, and trans to the NMe2 group. The nucleophilic character of the ylidic carbon atom promotes cleavage of the halide bridging systems of the dinuclear precursors [{Pd(µ-Br)(η3-C3H5)}2], [
{Pd(µ-Cl)(C–P)}2], [{Pd(µ-Cl)(C6F5)(tht)}2], [{Pd(µ-Cl)(dmba)}2], [{Pd(µ-Cl)(R-dmphea)}2], [{Pd(µ-Cl)[C6H2(OMe)2-4,5-CH
NCH2Ph-2]}2] and [{Pd(µ-Cl)Cl(PPh3)}2] (C–P = o-(di-o-tolylphosphino)benzyl; tht = tetrahydrothiophene), giving neutral mononuclear derivatives in which the ylide is selectively C-co-ordinated [PdBr(η3-C3H5){CH(CONMe2)(PPh3)}] 4, [PdCl(C–P){CH(CONMe2)(PPh3)}] 5, [PdCl(C6F5)(tht){CH(CONMe2)(PPh3)}] 6, [PdCl(dmba){CH(CONMe2)(PPh3)}] 7, [PdCl(R-dmphea){CH(CONMe2)(PPh3)}] 8, [PdCl{C6H2(OMe)2-4,5-CH
NCH2Ph-2}{CH(CONMe2)(PPh3)}] 9 and [PdCl2(PPh3){CH(CONMe2)(PPh3)}] 10. Complexes with the ylide co-ordinated through the heteroatom (oxygen or nitrogen) were not found. This selective C-co-ordination is discussed in terms of electronic and steric factors.