A novel mixed-valent MnIII–MnIV-dimer, [L2Mn2(µ-O)2(µ-MeCO2)][BPh4]2·MeCN: crystal structure, magnetic properties, and e.s.r. spectrum (L = 1,4,7-triazacyclononane)

Abstract

The green mixed-valence dimer [L₂Mn₂(µ-O)₂(µ-MeCO₂)][BPh₄]₂·MeCN (L = 1,4,7-triacacyclononane) is formed on hydrolysis of [L₂Mn₂(µ-O)(µ-MeCO₂)₂]²⁺ in water in the presence of air; characterization by X-ray crystallography showed the presence of the di-µ-acetato-dimanganese(III,IV) core, and temperature dependent magnetic susceptibility measurements indicate an S= 1/2 ground state and very strong intramolecular antiferromagnetic coupling (J–440 cm^–1).