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|Title:||Semi-batch homogeneous catalytic in-situ spectroscopic data. FTIR spectral reconstructions using band-target entropy minimization (BTEM) without spectral preconditioning|
|Source:||Widjaja, E., Li, C., Garland, M. (2002-04-29). Semi-batch homogeneous catalytic in-situ spectroscopic data. FTIR spectral reconstructions using band-target entropy minimization (BTEM) without spectral preconditioning. Organometallics 21 (9) : 1991-1997. ScholarBank@NUS Repository. https://doi.org/10.1021/om010933j|
|Abstract:||In the preceding paper in this issue, the concept of band-target entropy minimization (BTEM) was introduced, and it was successfully applied to spectral reconstruction from a stoichiometric organometallic reaction system after spectral preconditioning. In this contribution, the BTEM algorithm is reapplied to semi-batch homogeneous catalytic reactions without spectral preconditioning. The homogeneous catalytic hydroformylation of 3,3-dimethylbut-1-ene, starting with Rh4(σ-CO)9-(μ-CO)3 as catalyst precursor in n-hexane as solvent, was studied at 298 K and variable total pressure, using high pressure in situ infrared spectroscopy as the analytical tool. The non-preconditioned data were then subjected to BTEM in order to recover the pure component spectra of the species present. The pure component spectra of background moisture and carbon dioxide, hexane, dissolved CO in hexane, and the dissolved species present, namely the organic reactant 3,3-dimethylbut-1-ene, the organic product 4,4-dimethylpentanal, the catalyst precursor Rh4(σ-CO)9(μ-CO)3, the observable organometallic intermediate RCORh(CO)4, and Rh6(CO)16, were all readily recovered. An unexpected finding was a very well resolved spectrum with two terminal CO vibrations centered at 2068 and 2076 cm-1 (almost exactly overlapping with Rh4(σ-CO)9(μ-CO)3, but without bridging carbonyls). With reasonable certainty we are assigning this new spectrum to the previously unknown complex Rh4(σ-CO)12. The results indicate that spectral reconstruction, using no libraries and no a priori information, is indeed possible from semibatch runs. This finding holds promise for rapid and cost-effective spectroscopic system identification of reactive organometallic and homogeneous catalytic systems.|
|Appears in Collections:||Staff Publications|
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