90502-88-8Relevant academic research and scientific papers
Formation and molecular structures of η5-pentabenzylcyclopentadienyl and η5-pentaphenylcyclopentadienyl dicarbonyl derivatives of cobalt and rhodium
Chambers, John W.,Baskar, Andrew J.,Bott, Simon G.,Atwood, Jerry L.,Rausch, Marvin D.
, p. 1635 - 1641 (2008/10/08)
Improved synthetic routes to pentabenzylcyclopentadiene (1) and pentaphenylcyclopentadiene (2) have been developed. Reactions of 1 and 2 with Co2(CO)8 in refluxing toluene have afforded (η5-C5Bz5)Co(CO)2 (3) and (η5-C5Ph5)Co(CO)2 (5) in yields of 67% and 9%, respectively. Reaction of 1 with n-butyllithium in THF at 0?C has produced C5Bz5Li (7), whereas reaction of 2 with sodium amide in refluxing toluene has afforded C5Ph5Na (8) in 84% yield. Both 7 and 8 react with [Rh(CO)2Cl]2 in THF to produce (η5-C5Bz5)Rh(CO)2 (4) and (η5-C5Ph5)Rh(CO)2 (6), respectively. Single-crystal X-ray diffraction studies on 3 and 5 have been undertaken. Compound 3 crystallizes in the monoclinic space group P21/n with unit cell dimensions a = 12.753 (7) A?, b = 14.877 (8) A?, c = 18.28 (1) A?, β = 108.58 (5)°, and Z = 4 for dcalcd = 1.28 g cm-3. Compound 5 crystallizes in the orthorhombic space group Pbca with unit cell dimensions a = 13.66 (1) A?, b = 20.44 (4) A?, c = 20.600 (5) A?, and Z = 8 for dcalcd = 1.30 g m-3. Full-matrix least-squares refinement led for 3 to a final R value of 0.042 for 2398 observed reflections and for 5 to a final R value of 0.054 for 1779 observed reflections. Compound 3 exhibits a nonsymmetric placement of the benzyl substituents, while the phenyl substituents of 5 are symmetrically placed and canted an average of 55.8° with respect to the cyclopentadienyl ring.
Reduction-Oxidation Properties of Organotransition-metal Complexes. Part 23. Pentaphenylcyclopentadienyl Carbonyl Complexes of Cobalt and Rhodiu
Conelly, Neil G.,Raven, Stephen J.
, p. 1613 - 1618 (2007/10/02)
The reaction of or 2> with C5Ph5Br and zinc dust in tetrahydrofuran (thf) gives (1,M=Co or Rh); in the case of rhodium, the intermediate is isolable if the reaction is carried out in benzene.In the presence of +, (1,M=Rh) undergoes oxidatively-induced carbonyl substitution with ligands, L; for L=P(OPh)3, the formation of is catalytic in the oxidant.The complexes (2) are also prepared via (a) the substitution of with PPh3 or AsPh3 and subsequent reduction by , (b) reduction of (3,M=Co) in the presence of P(OMe)3 or P(OPh)3, or (c) reduction of (η-C5Ph5)> (5) in the presence of CO.Complexes (3,M=Co or Rh) are prepared from (1) and iodine in toluene-hexane at 0 deg C; the rhodium complex (3,M=Rh) is reduced by to give 2>.Compound (5) results from the addition of P(OMe)3 to 2> (4), which is the product of the reaction between (1,M=Rh) and bromine in CH2Cl2.The compounds (2) undergo two one-electron oxidations at a platinium electrode in CH2Cl2; the first is reversible and the second is irreversible.The monocations have been characterised in solution by i.r. and e.s.r. spectroscopy.Low-temperature e.s.r. spectroscopy has shown that the radical cation + is stable at -196 deg C.
