Solution Infrared Spectroscopic Studies on Equilibrium Reactions of CO with the Decamethylmetallocenes Cp*2MII, Where MII = Mg, Ca, Sr, Ba, Sm, Eu, Yb
Selg, Peter, Brintzinger, Hans H., Schultz, Madeleine, & Andersen, Richard A. (2002) Solution Infrared Spectroscopic Studies on Equilibrium Reactions of CO with the Decamethylmetallocenes Cp*2MII, Where MII = Mg, Ca, Sr, Ba, Sm, Eu, Yb. Organometallics, 21(15), pp. 3100-3107.
The reaction of CO with the alkaline-earth decamethylmetallocenes Cp*2MII, where MII is Mg, Ca, Sr, or Ba, and the bivalent lanthanide decamethylmetallocenes, where MII is Sm, Eu, or Yb, have been studied in toluene or methylcyclohexane solution in a high-pressure infrared cell. In all cases, except for Mg and Ba, the monocarbonyl complex Cp*2MCO is observed to form under CO pressure. The CO stretching frequencies for Cp*2CaCO (2158 cm-1), Cp*2SrCO (2159 cm-1), Cp*2SmCO (2153 cm-1), and Cp*2EuCO (2150 cm-1) are greater than that of free CO (2134 cm-1 in toluene or methylcyclohexane). In contrast, Cp*2YbCO has nuCO 2114 cm-1, below that of free CO. This 1:1 complex is formed at low CO pressure (<2 bar); at higher CO pressures the 1:2 adduct Cp*2Yb(CO)2 with an even lower nuCO value of 2072 cm-1 predominates. Equilibrium constants were determined as a function of pressure and temperature for the equilibria Cp*2MII(solv) + nCO(gas or solv) Cp*2MII(CO)n(solv), with MII = Ca, Eu, Yb. The thermodynamic constants delta H degrees, delta S degrees, and delta G degrees for the formation of each species, extracted from the changes in the intensity of the corresponding iotaR absorption bands, indicate weak MII-CO binding. Models to account for the bonding in these metallocene CO adducts are discussed.
Citation countsare sourced monthly fromand citation databases.
These databases contain citations from different subsets of available publications and different time periods and thus the citation count from each is usually different. Some works are not in either database and no count is displayed. Scopus includes citations from articles published in 1996 onwards, and Web of Science® generally from 1980 onwards.
Citations counts from theindexing service can be viewed at the linked Google Scholar™ search.
|Item Type:||Journal Article|
|Additional Information:||This article is freely available from the American Chemical Society website 12 months after the publication date. See links to publisher website in this record.|
|Subjects:||Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > OTHER CHEMICAL SCIENCES (039900) > Organometallic Chemistry (039904)|
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Science and Technology|
|Copyright Owner:||Copyright 2002 American Chemical Society|
|Deposited On:||20 Aug 2007|
|Last Modified:||09 Mar 2011 11:58|
Repository Staff Only: item control page