Étude par spectrométrie infra-rouge des complexes des terres rares avec l'oxyde de tri-n-butylphosphine á l'état solide

Tri-n-butylphosphine oxide (TBPO) reacts with rare earth nitrates to form complexes of general formula Me(NO₃)₃·3 TBPO. These complexes were studied by infrared spectrometry. The coordination of the nitrates is not the same along the lanthanide series. They are bidentate for the light rare earths and monodentate for the heavy earths. The P=O frequency does not vary monotonously when Z increases; there is a break for gadolinium. This is explained by an influence of backbonding, the decrease of the ionic radius and the coordination number.