Anomalous triplet-state behaviour in solid tris(dipivaloylmethanato)terbium(III)

Abstract

Fluorescent decay times of solid Tb(dpm)₃ and its monoadducts with EtOH, EtOD, and pyridine have been determined over the temperature range 77—323 K. The decay time of Tb(dpm)₃, in contrast to the adducts, is markedly temperature-dependent. This anomalous behaviour is interpreted as a result of thermal population of a low-lying triplet state in Tb(dpm)₃ that does not occur in the adducts. This is supported by examination of analogous gadolinium complexes and the occurrence of this triplet is correlated with the known dimeric structure of Tb(dpm)₃.