12150-70-8Relevant academic research and scientific papers
Ion-pairing thermodynamics for (η5-pentadienyl)Fe(CO)2- (pentadienyl = MeCp, C5Me5, C5Ph5, C9H7) and x-ray crystal structure of [(η5-C5Ph5)Fe(CO)2][PPN]
Carter, Bruce T.,Castellani, Michael P.,Rheingold, Arnold L.,Hwang, Seonggyu,Longacre, Steven E.,Richmond, Michael G.
, p. 373 - 379 (2002)
The pentadienyl complexes [(η5-pentadienyl)Fe(CO)2] [Na] (pentadienyl = MeCp, C5Me5, C5Ph5, C9H7) have been prepared in THF from the corresponding dimers [(η5-pentadienyl)-Fe(CO)2]2 and (η5-C5Ph5)Fe(CO)2Br. The exact composition of the ion pairs that exist in THF solution was explored as a function of temperature by FT-IR spectroscopy. The sodium metalates bearing the pentadienyl ligands MeCp, C5Me5, and C9H7 show the presence of two species that involve carbonyl oxygen-sodium and iron-sodium contact ion pairs in THF. In contrast, the pentaphenylcyclopentadienyl complex [(η5-C5Ph5)Fe(CO)2] [Na] reveals the existence of solvent-separated ion pairs and carbonyl oxygen-sodium contact ion pairs. The absence of iron-sodium contact ion pairs in [(η5-C5Ph5)Fe(CO)2] [Na] is attributed to a steric shielding of the iron center by the ancillary phenyl groups. The temperature-dependent behavior of these sodium metalates was explored by variable-temperature FT-IR measurements, and the equilibrium constants for the observed ion-pairing equilibria have been used to determine values for ΔH and ΔS. The X-ray structure of [(η5-C5Ph5)Fe(CO)2] [PPN] is reported. The reactivity of [(η5-C5Ph5)Fe(CO)2]- with CO2 was investigated, and only in the case of the lithium salt was the carboxylate complex [(η5-C5Ph5)Fe(CO)2(CO2 )]- observed by IR spectroscopy.
