Reactions of benzyldiphenylphosphine with Pd(II) sources on silica gel

Depending on the conditions used, reactions of benzyldiphenylphosphine (HL1) with Na2PdCl4 on silica gel or with Pd(OAc)2 on the same absorbent followed by treatment with LiCl provide one or more of the four compounds: the cyclopalladated binuclear complex [(μ-Cl)PdL1]2 (1), cis and trans isomers of the coordination complex PdCl2(HL1)2 (3), the binuclear coordination complex [(μ-Cl)PdCl(HL1)]2 (4), and compound PdCl2(HL1)3 (5). The 56% yield of complex 1 achieved using the reaction with Na2PdCl4 and NaOAc on SiO2 is higher than that reported for the direct cyclopalladation of PBnPh2 with Pd(OAc)2 in AcOH. X-ray diffraction studies of the cyclopalladated dimer 1 and the coordination complex cis-3 are reported.

Graphical AbstractDepending on the conditions used, reactions of benzyldiphenylphosphine (HL1) with Pd(OAc)2 or Na2PdCl4 on silica gel provide one or more of the four compounds: the cyclopalladated binuclear complex [(μ-Cl)PdL1]2 (1), cis and trans isomers of the coordination complex PdCl2(HL1)2 (3), the binuclear coordination complex [(μ-Cl)PdCl(HL1)]2 (4), and compound PdCl2(HL1)3 (5).Figure optionsDownload as PowerPoint slideHighlights
► BnPPh2 reacts with Na2PdCl4 on SiO2 at 120 °C to form a cyclopalladated complex.
► BnPPh2 (HL) reacts with Na2PdCl4 on SiO2 at 40 °C to yield PdCl2(HL)2 and PdCl2(HL)3.
► BnPPh2 (HL) reacts with Pd(OAc)2 on SiO2 at 50 °C to form [(μ-Cl)PdCl(HL)]2.
► X-ray structures of complexes [(μ-Cl)PdL]2 and cis-PdCl2(HL)2 are reported.