Homogeneous Hydrogenation of Norbornadiene with Parahydrogen and Phosphonic Ester Phosphine Rhodium Complexes Studied by in situ NMR Spectroscopy
Homogeneous hydrogenation of norbornadiene with enriched parahydrogen (p-H2) and phosphonic ester phosphine rhodium complexes is detected using in situ NMR spectroscopy The obtained polarization spectra remain unchanged during the catalysis in thf-d8 as a solvent but change with time when the hydrogenation is executed in acetone-d6. The observed phenomenon is attributed to a change of the phase correlation of the transferred parahydrogen nuclei via nuclear singlet-triplet (S/T0) mixing during the reaction. Simultaneously, 31P NMR spectra change indicating a change in the nature of the original rhodium complex when the hydrogenation is carried out in acetone-d6.
A. Harthun et al., "Homogeneous Hydrogenation of Norbornadiene with Parahydrogen and Phosphonic Ester Phosphine Rhodium Complexes Studied by in situ NMR Spectroscopy," Tetrahedron, vol. 51, no. 41, pp. 11199-11206, Elsevier, Oct 1995.
The definitive version is available at http://dx.doi.org/10.1016/0040-4020(95)00687-4
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