Slow magnetization dynamics in Co( ii )/Co( iii ) triethanolamine/pivalate complexes

SARTO, CAROLINA; ROUZIÈRES, MATHIEU; LIU, JUN-LIANG; BAMBERGER, HEIKO; VAN SLAGEREN, JORIS; CLÉRAC, RODOLPHE; ALBORÉS, PABLO

DALTON TRANSACTIONS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2018 vol. 47 p. 17055 - 17066

1477-9226

We report the synthesis, structural characterization and a combined computational and experimental study of the magnetic properties of two pivalate cobalt complexes, a mononuclear Co(II) one and a tetranuclear Co(II)3Co(III) mixed valence polynuclear one. The latter shows SMM behaviour revealed under an applied DC field with a thermal barrier of ca. 30 cm−1 competing with direct and Raman relaxation processes. The Orbach thermal barrier can be understood from the doublets energy ladder arising from the anisotropic exchange interaction among ground Seff = 1/2 of each Co(II) sites. The strong local zero-field splitting of the S = 3/2 Co(II) states affords these well isolated ground Kramers doublets. DC and AC magnetic susceptibility measurements as well as HF-EPR spectra support this interpretation. CASSCF quantum chemical computations have been also performed in order to aid the overall comprehension of the magnetic behaviour in the reported complexes.