710339-35-8Relevant academic research and scientific papers
An NMR study of the rotational barriers in cobalt-stabilized carbocations: X-ray crystal structures of (η4-C4Ph4)Co-(η5 -C5H4R), where R is CH3C=O, CH=O, CH(tBu)OH
Ortin, Yannick,Ahrenstorf, Kirsten,O'Donohue, Paul,Foede, Daniel,Müller-Bunz, Helge,McArdle, Patrick,Manning, Anthony R.,McGlinchey, Michael J.
, p. 1657 - 1664 (2007/10/03)
Treatment of the aldehyde (η4-C4Ph4) Co(η5-C5H4-CH=O) (4b) with tert-butyllithium or phenyllithium yields the secondary alcohols (η4-C4Ph4)Co(η5- C5H4-CH(R)OH), where R=tert-butyl (5) or phenyl (6 . Protonation of 5 and 6 at -80 °C furnishes the deep purple, cobalt-stabilized cations, 7 and 8, respectively, both of which exhibit restricted rotation about the external C5H4 -CHR+ linkage on the NMR time-scale. These data indicate a minimum value for the barrier to rotation of 15 kcal mol-1, but it is certainly much higher, indicating a considerable degree of C-C double bond character. X-ray crystal structures of 4b, 5 and also of the ketone (η4-C4Ph4 Co(η5 -C5H4-C(=O)CH3 (4a) are reported. The secondary alcohol 5 exhibits disorder in the solid state because of the presence of diastereomers as a consequence of the stereogenic center at the α-carbon and the clockwise or anticlockwise propeller orientations of the tetraphenylcyclobutadiene ligand.
