HOMOGENEOUS HYDROGENATION OF NORBORNADIENE WITH PARAHYDROGEN AND PHOSPHONIC ESTER PHOSPHINE RHODIUM COMPLEXES STUDIED BY IN-SITU NMR-SPECTROSCOPY

1) Homogeneous hydrogenation of norbornadiene with enriched parahydrogen (p-H-2) and phosphonic ester phosphine rhodium complexes is detected using in situ NMR spectroscopy. The obtained polarization spectra remain unchanged during the catalysis in thf-d(8) as a solvent but change with time when the hydrogenation is executed in acetone-d(6). 2) The observed phenomenon is attributed to a change of the phase correlation of the transferred parahydrogen nuclei via nuclear singlet-triplet (S/T-0) mixing during the reaction. 3) Simultaneously, P-31 NMR spectra change indicating a change in the nature of the original rhodium complex when the hydrogenation is carried out in acetone-d(6).