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 parahydrog en (p-H-2) and phosphonic ester phosphine rhodium complexes is detecte d using in situ NMR spectroscopy. The obtained polarization spectra re main unchanged during the catalysis in thf-d(8) as a solvent but chang e with time when the hydrogenation is executed in acetone-d(6). 2) The observed phenomenon is attributed to a change of the phase correlatio n 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 comp lex when the hydrogenation is carried out in acetone-d(6).