102539-05-9Relevant 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.
