C-13 AND H-1 SPIN-LATTICE RELAXATION-TIMES STUDY ON FREE AND CR(CO)(3) COMPLEXES OF BENZOPHENONE AND 9-FLUORENONE

Carbon-13 and hydrogen-1 spin lattice relaxation times have been measu red for benzophenone and 9-fluorenone, both as free ligands and comple xed with the tricarbonylchromium group. The experimental results were then compared with the values calculated by considering the magnetic d ipolar interactions. The comparison appears to be reasonably good and shows that, in these molecules, the contribution to the overall relaxa tion rate is essentially of magnetic dipolar nature for all the nuclea r species present including the non-hydrogenated carbon nuclei. Only e xception are the keto-carbonyl C-13 nuclei relaxation times, for which substancial CSA contributions are also involved.