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Solution infrared spectroscopic studies on equilibrium reactions of CO with the decamethylmetallocenes Cp*<sub>2</sub>M<sup>II</sup>, where M<sup>II</sup> = Mg, Ca, Sr, Ba, Sm, Eu, Yb

Solution infrared spectroscopic studies on equilibrium reactions of CO with the decamethylmetallocenes Cp*2MII, where MII = Mg, Ca, Sr, Ba, Sm, Eu, Yb

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SELG, Peter, Hans-Herbert BRINTZINGER, Madeleine SCHULTZ, Richard A. ANDERSEN, 2002. Solution infrared spectroscopic studies on equilibrium reactions of CO with the decamethylmetallocenes Cp*2MII, where MII = Mg, Ca, Sr, Ba, Sm, Eu, Yb. In: Organometallics. 21(15), pp. 3100-3107. ISSN 0276-7333. eISSN 1520-6041. Available under: doi: 10.1021/om011045r

@article{Selg2002Solut-23728, title={Solution infrared spectroscopic studies on equilibrium reactions of CO with the decamethylmetallocenes Cp*2MII, where MII = Mg, Ca, Sr, Ba, Sm, Eu, Yb}, year={2002}, doi={10.1021/om011045r}, number={15}, volume={21}, issn={0276-7333}, journal={Organometallics}, pages={3100--3107}, author={Selg, Peter and Brintzinger, Hans-Herbert and Schultz, Madeleine and Andersen, Richard A.} }

Selg, Peter 2002 2013-06-20T15:16:20Z Brintzinger, Hans-Herbert The reaction of CO with the alkaline-earth decamethylmetallocenes Cp*<sub>2</sub>M<sup>II</sup>, where M<sup>II</sup> is Mg, Ca, Sr, or Ba, and the bivalent lanthanide decamethylmetallocenes, where M<sup>II</sup> 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*<sub>2</sub>MCO is observed to form under CO pressure. The CO stretching frequencies for Cp*<sub>2</sub>CaCO (2158 cm<sup>-1</sup>), Cp*<sub>2</sub>SrCO (2159 cm<sup>-1</sup>), Cp*<sub>2</sub>SmCO (2153 cm<sup>-1</sup>), and Cp*<sub>2</sub>EuCO (2150 cm<sup>-1</sup>) are greater than that of free CO (2134 cm<sup>-1</sup> in toluene or methylcyclohexane). In contrast, Cp*<sub>2</sub>YbCO has νCO 2114 cm<sup>-1</sup>, 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*<sub>2</sub>Yb(CO)<sub>2</sub> with an even lower νCO value of 2072 cm<sup>-1</sup> predominates. Equilibrium constants were determined as a function of pressure and temperature for the equilibria Cp*<sub>2</sub>M<sup>II</sup>(solv) + nCO(gas or solv) Cp*<sub>2</sub>M<sup>II</sup>(CO)<sub>n</sub>(solv), with M<sup>II</sup> = Ca, Eu, Yb. The thermodynamic constants ΔH°, ΔS°, and ΔG° for the formation of each species, extracted from the changes in the intensity of the corresponding ΙR absorption bands, indicate weak M<sup>II</sup>−CO binding. Models to account for the bonding in these metallocene CO adducts are discussed. Schultz, Madeleine Andersen, Richard A. terms-of-use eng Solution infrared spectroscopic studies on equilibrium reactions of CO with the decamethylmetallocenes Cp*<sub>2</sub>M<sup>II</sup>, where M<sup>II</sup> = Mg, Ca, Sr, Ba, Sm, Eu, Yb Schultz, Madeleine Selg, Peter Brintzinger, Hans-Herbert Andersen, Richard A. Organometallics ; 21 (2002), 15. - S. 3100-3107 2013-06-20T15:16:20Z

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