Design, Synthesis, and Chemistry of Sterically Nondemanding Primary Bisphosphines¹

Design and synthesis of chelating bisphosphines functionalized with the smallest chemical unit “H” on the P^III centers ((PH₂CH₂)₂CHCH₂NHPh (4) and (PH₂CH₂)₂CHCONHPh (5)) are described. Studies demonstrating that no bulky chemical substituents are necessary to offer thermal/oxidative stability to the −PH₂ groups in 4 and 5 are described. The H atoms around the P^III centers in 5 (or 4) concur limited/no steric influence, but yet the phosphines manifest high nucleophilicity to coordinate strongly with W(0) and Re(I). The studies include synthesis and X-ray structural characterization of an air-stable primary bisphosphine (5) and its transition-metal chemistry with W(CO)₆ and Re(CO)₅Br to produce the complexes (η²-(PH₂CH₂)₂CHCONHPh)W(CO)₄ (6) and (η²-(PH₂CH₂)₂CHCONHPh)Re(CO)₃Br (7), respectively.