Insights into the Spin Dynamics of Mononuclear Cerium(III) Single-Molecule Magnets.

Four novel Ce III mononuclear complexes of formulas [Ce(ntfa) 3 (MeOH) 2 ] ( 1 ), [Ce(ntfa) 3 (5,5'-Me 2 bipy)] ( 2 ), [Ce(ntfa) 3 (terpy)] ( 3 ), and [Ce(ntfa) 3 (bipy) 2 ] ( 4 ), where ntfa = 4,4,4-trifluoro-1-(naphthalen-2-yl)butane-1,3-dionato, 5,5'-Me 2 bipy = 5,5'-dimethyl-2,2'-dipyridyl, terpy = 2,2':6',2″-terpyridine, and bipy = 2,2'-bipyridine, have been synthesized and structurally characterized with Ce III displaying coordination numbers of 8, 8, 9, and 10, respectively. Magnetic measurements indicate that all the complexes show a field-induced single-ion magnet behavior under a small applied dc field. The magnetic analysis shows the relevance of the different spin relaxation mechanisms in the magnetic relaxation of the Ce III compounds, with special emphasis on the local-mode process. Multiconfigurational calculations were also performed to get more information on the axiality of the compounds.