Synthesis and structures of η1-allenyl and/or -propargyl Pd(II) complexes and their reactivity toward trimethylsilyl pseudohalides, organic thiols, and N-heterocyclic carbene ligands

Facile oxidative additions of various propargyl halides to [Pd(CH2CHPh)(PR3)2], which could be generated in situ from trans-[PdEt2(PR3)2] (PR3PMe3, PEt3, PMe2Ph) and styrene, gave the bis(phosphine) η1-allenyl and/or η1-propargyl Pd(II) complexes. The chloro ligand in the η1-allenyl Pd(II) complex could be replaced by pseudohalides to produce the new corresponding pseudohalo complexes, trans-[XPd(CHCCH2)(PMe3)2], when treated with trimethylsilyl pseudohalides (Me3SiX: X = NCS, CN, N3). The η1-allenyl complex was also converted into the thiolato complexes when treated with various organic thiols. In addition, the phosphine ligand in the η1-allenyl complex could be replaced by NHC (N-heterocyclic carbene) to produce η1-allenyl or -propargyl Pd(II) complex possessing the NHC ligand, depending on the coordinated η1-allenyl moiety. On the other hand, oxidative addition of phenyl propargyl sulfide to the [Pd(CH2CHPh)(PMe3)2] gave a phenyl thiolato η1-allenyl Pd(II) complex, trans-[(C6H5S)Pd(CHCCH2)(PMe3)2].