Magnetic Study of a Pentanuclear {Co2 IIICo3 II} Cluster with a Bent {CoII 3} Motif

IRENE C. LAZZARINI; ALEJANDRO V. FUNES; LUCA CARRELLA; LORENZO SORACE; EVA RENTSCHLER; PABLO ALBORÉS

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY

WILEY-V C H VERLAG GMBH

Año: 2014 vol. 2014 p. 2561 - 2568

1434-1948

We have synthesised and structurally characterised a new pentanuclear mixed-valent cobalt cluster of formula [CoII 3CoIII2(OH)2(piv)6(L)2(H2O)4] (piv = trimethylacetate, H2L = salicylideneanthranillic acid) from reaction of a di-nuclear cobalt pivalate precursor with a Schiff base type ligand under mild reaction conditions. The core structure can be conveniently described as two fused Co3?μ3?OH triangles with a strict unique sharing vertex point. A complete picture of the magnetic behaviour of this compound is presented. Through combined use of susceptibility, magnetisation, and EPR data as well as broken-symmetry DFT calculations, we have supported the magnetic data that show weak and anisotropic exchange interaction between CoII ions affording an Seff = 1/2 ground state that is not completely isolated from the low-lying excited doublets at low temperature. Under the optimum applied field of 2 kOe, a frequency-dependent out-of-phase susceptibility signal can be observed below 4 K. However, no reliable relaxation rates could be extracted due to the narrow temperature range in which this behaviour was observed.