Magnetic Study of a Pentanuclear {Co2IIICo3II} Cluster with a Bent {CoII3} Motif. Issue 15 (11th April 2014) - Lazzarini, Irene C.
Abstract: We have synthesised and structurally characterised a new pentanuclear mixed‐valent cobalt cluster of formula [Co II 3 Co III 2 (OH)2 (piv)6 (L)2 (H2 O)4 ] (piv = trimethylacetate, H2 L = salicylideneanthranillic acid) from reaction of a dinuclear 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 Co II 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. Abstract : We report a new pentanuclear mixed‐valent cobalt cluster exhibiting a {Co II 3 Co II 2 } core that can be conveniently described as two fused Co3 –μ3 –OH triangles with a strict unique sharing vertex point. We have analysed its magnetic behaviour by combining susceptibility, magnetisation and EPR data as well as broken‐symmetry DFT calculations.