113747-48-1Relevant articles and documents
One-electron oxidation of (η4-cot)RhCp: Rearrangements of the radical cation and of the resulting dimerization product
Brammer, Lee,Connelly, Neil G.,Edwin, Joseph,Geiger, William E.,Orpen, A. Guy,Sheridan, John B.
, p. 1259 - 1265 (2008/10/08)
The complex (η4-Cot)RhCp (Cot = cyclooctatetraene; 3) undergoes an irreversible one-electron oxidation to a transient radical cation. Detailed voltammetric studies suggest that the radical rearranges to (η5-C8H8)RhCp+ before dimerizing through the allyl radical section of the C8 ring. Anodic or chemical oxidation (using [FeCp2]+ or AgPF6) in CH2Cl2 gives the C-C bonded dimer [(η5:η′5-C16H 16)Rh2Cp2][PF6]2 (4) which thermally isomerizes to [(η2,η3:η′2,η′ 3-C16H16)Rh2Cp2][PF 6]2 (2b) and then to [η2,η3:σ′,η′ 4-C16H16)Rh2Cp2][PF 6]2 (5). The asymmetric species 5 has been fully characterized as the [BPh4]- salt by single-crystal X-ray diffraction. Crystallographic data: C74H66B2Rh2, a = 20.421 (5) A?, b = 15.198 (2) A?, c = 19.528 (4) A?, β = 114.10 (2)°, space group P21/c, R = 0.083, Rw = 0.077. The dication of 5 contains two rhodium atoms, each carrying an η5-cyclopentadienyl ring bridged [Rh?Rh = 6.514 (2) A?] by a C16H16 ligand. The ligand is formally derived from two Cot molecules by formation of three C-C bonds linking the two original C8 rings. The resultant tetracyclic ligand bonds via σ,η4- and η2,η3-linkages to the two rhodium atoms, acting as a five-electron donor to each.
