12427-78-0Relevant articles and documents
Enantioselective synthesis and application to the allylic imidate rearrangement of amine-coordinated palladacycle catalysts of cobalt sandwich complexes
Cassar, Doyle J.,Ilyashenko, Gennadiy,Ismail, Muhammad,Woods, James,Hughes, David L.,Richards, Christopher J.
, p. 17951 - 17962 (2014/01/17)
The reaction of (η5-(N,N-dimethylaminomethyl)cyclopentadien- yl)(η4-tetraphenylcyclobutadiene)cobalt with sodium tetrachloropalladate and (R)-N-acetylphenylalanine gave planar chiral palladacycle di-μ-chloridebis[(η5-(Ssu
Synthesis and 1H NMR spectroscopic properties of substituted (η4-tetraarylcyclobutadiene)(η5-cyclopentadienyl)cobalt metallocenes
Nguyen, Huy V.,Yeamine, Mebuba R.,Amin, Jahangir,Motevalli, Majid,Richards, Christopher J.
, p. 3668 - 3676 (2009/03/11)
The reaction of diarylacetylenes with CoCl(PPh3)3 and sodium cyclopentadienylide or sodium carbomethoxycyclopentadienylide gave (η4-tetra-arylcyclobutadiene)(η5-cyclopentadienyl)cobalt and (η4-tetra-arylcyclobutadiene)(η5-carbomethoxycyclopentadienyl)cobalt, respectively, where aryl = para-XC6H4 (X = CF3, F, MeO). The reaction was unsuccessful for the synthesis of (η4-tetra(para-methoxyphenyl)cyclobutadiene)(η5-cyclopentadienyl)cobalt, which was synthesised instead from dicarbonyl(η5-cyclopentadienyl)cobalt. In all of the examples starting with CoCl(PPh3)3 an intermediate (η5-cyclopentadienyl)- or (η5-carbomethoxycyclopentadienyl)(triphenylphosphine)-2,3,4,5-tetraarylcobaltacyclopentadiene complex was isolated, and two examples were characterised by X-ray crystallography. Heating the (η5-cyclopentadienyl)- or (η5-carbomethoxycyclopentadienyl)(triphenylphosphine)-2,3,4,5-tetraarylcobaltacyclopentadiene complexes resulted in clean conversion to the corresponding metallocenes. The influence of the para-aryl substituents on the 1H NMR of the cyclopentadienyl moiety is tabulated, together with the influence of a range of R substituents in (η4-tetraphenylcyclobutadiene)(η5-RC5H4)cobalt (R = CO2Me, CH2OH, Me, CHO, CCH, CO2H, CN, CONHR1, 2-oxazolinyl, NH2, NHAc, HgCl, Br, I, SiMe3, SnMe3, Ph).
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.
