199849-99-5Relevant academic research and scientific papers
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).
Oligoalkyne-bridged (η4-cyclobutadiene)(η5-cyclopentadienyl)cobalt fragments - Syntheses and properties
Classen, Joerg,Gleiter, Rolf,Rominger, Frank
, p. 2040 - 2046 (2007/10/03)
The syntheses of (η5-cyclopentadienyl)(η4 -tetraphenylcyclobutadiene)cobalt units bridged by buta-1,3-diyne, octa-1,3,5,7-tetrayne, and dodeca-1,3,5,7,9,11-hexayne units (15, 18, 21) are reported. All three species could be obtained by Hay coupling of the corresponding mono-, di-, and triyne units 14, 17, and 20. In the case of 14-17 and 21, the molecular structures were confirmed on the basis of X-ray studies on single crystals. Cyclic voltammetry revealed a weak interaction between the metal centers of 15 and no interaction between the metal centers of 18 and of 21. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
