A Dinuclear Co(III)/Co(II) complex based on the H2pmide ligand showing field-induced SMM behaviour

CABROSI, DAIANA; CRUZ, CARLOS; PAREDES-GARCÍA, VERÓNICA; PABLO ALBORES

DALTON TRANSACTIONS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2023 vol. 52 p. 175 - 184

1477-9226

We are reporting the synthesis, structural characterization and SMM behaviour study of a new mixed valence Co(II)/Co(III) dinuclear complex bearing the H2pmide ligand. Well defined molecules pairs are observed in the crystal structure hold on through H-bond interaction directed by aqua ligands. From DC magnetometry data, a spin-only Hamiltonian approach including axial zero-field splitting term seems to be enough for a reasonable modelling, with a sizeable D parameter close to 40 cm-1. First order orbital contribution is extensively quenched due to strong distortion from octahedral symmetry of Co(II) site. Quantum computation at the CASSCF level supports this interpretation. To model low temperature magnetization data, the H-bond inter-molecular exchange interaction is required, with a magnitude close to -1 cm-1, well supported by Broken-Symmetry DFT computation. This exchange is highly anisotropic due to the existence of a well isolated Kramers doublet at Co(II) site. AC susceptibility shows field-induced SMM behaviour with competing Orbach and Raman relaxation pathways as well as quantum tunnelling process at the lowest probed temperatures. The Orbach thermal barrier agrees with the expected one from combined experimental and quantum computed DC magnetometry analysis.