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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. 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 deposit-license 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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