Protonation of Zwitterionic Manganese and Rhenium Phosphoniostyryl Complexes (η 5 ‐C 5 H 5 )(CO) 2 M – –C( + PR 3 )=C(H)Ph: Experimental and DFT Study
Résumé
Protonation of Mn and Re Z-σ-phosphoniostyryl complexes 3–7 with HBF4·OEt2 leads to the E-η2-phosphonioalkene derivatives 8–12 rather than the phosphoniocarbene complexes 13. According to DFT calculations, protonation of Mn complex 5 proceeds at the metal atom followed by fast conversion of the resulting cis-hydride 14 into the agostic intermediate 15 and the final product 10. Quantitative formation of the cis-hydride intermediates 16 and 17 was evidenced by low-temperature protonation of the rhenium Z-σ-phosphoniostyryl complexes 6 and 7 with triflic acid.