Reactions of (cyclopentadienyl)rhenium halide complexes (η5‐C5H5)Re(NO)(PPh3)(X) with n‐BuLi/TMEDA; Generation and Methylation of Lithio‐ and Dilithiocyclopentadienyl Ligands

Reactions of halide complexes (η5‐C5H5)Re(NO)(PPh3)(X) [1, X = Cl (a), Br (b), I (c)] with n‐BuLi/TMEDA (1.1 equiv., THF, – 78°C) give lithiocyclopentadienyl complexes (η5‐C5H4Li)Re(NO)(PPh3)(X) (2), as assayed by NMR and subsequent methylation to (η5‐C5H4CH3)Re(NO)(PPh3)(X) (3). Reaction of 2a With further n‐BuLi/TMEDA affords (0°C) dilithiocyclopentadienyl complex (η5‐1,3‐C5H3Li2)Re(NO)(PPh3)(Cl)(4), as assayed by NMR and methylation to [η5‐1,3‐C5H3(CH3)2]Re(NO)(PPh3)(Cl) (5). No significant migration of the halide ligand to the lithiocyclopentadienyl ligand is observed. New compounds 3a–c and 5 are characterized by NMR (1H, 13C, 31P), IR, mass spectrometry, and microanalysis.