Extending the Application Scope of Organophosphorus(V) Compounds in Palladium(II) Pincer Chemistry

1-Dimethylthiocarbamoyloxy-3-diphenylphosphinobenzene was used as a key precursor for the synthesis of a whole series of organophosphorus(V) pincer ligands combining thiocarbamate donor group with P═X coordination arm, where X = S, Se, O, NR (R = Ph, 4-NO2C6H4, COOtBu, CH2Ph) or CHR′ (R′ = COOEt, CN). Direct cyclopalladation of the ligands obtained (used either as individual compounds or generated in situ in the reaction mixture) afforded hybrid pincer complexes with five- and six-membered fused metallacycles. In the case of phosphine sulfide and phosphine selenide derivatives, the cyclopalladation can readily be accomplished in CH2Cl2 at room temperature, leading to the target pincer complexes in high yields. Their phosphine imide and phosphonium ylide counterparts can also be obtained under mild reaction conditions, but the yields strongly depend on the ligand stability (35–93%). Even in the case of the phosphoryl-functionalized ligand, the desired pincer-type complex was synthesized in ca. 15% yield, a...