Synthetic, structural, spectroscopic and theoretical study of a Mn(III)-Cu(II) dimer containing a Jahn-Teller compressed Mn ion

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 42; no. 1; pp. 207 - 216
• Main Authors: Berg, Nelly, Hooper, Thomas N, Liu, Junjie, Beedle, Christopher C, Singh, Saurabh Kumar, Rajaraman, Gopalan, Piligkos, Stergios, Hill, Stephen, Brechin, Euan K, Jones, Leigh F
• Format: Journal Article
• Language: English
• Published: England 07.01.2013
• Subjects: Anisotropy; Antiferromagnetism; Clusters; Compressed; Ion exchangers; Mathematical analysis; Orbitals; Stems
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt31995k

The heterobimetallic complex [Cu(II)Mn(III)(L)(2)(py)(4)](ClO(4))·EtOH (1) built using the pro-ligand 2,2'-biphenol (LH(2)), contains a rare example of a Jahn-Teller compressed Mn(III) centre. Dc magnetic susceptibility measurements on 1 reveal a strong antiferromagnetic exchange between the Cu(II) and Mn(III) ions mediated through the phenolate O-atoms (J = -33.4 cm(-1)), with magnetisation measurements at low temperatures and high fields suggesting significant anisotropy. Simulations of high-field and high frequency powder EPR data suggest a single-ion anisotropy D(Mn(III)) = +4.45 cm(-1). DFT calculations also yield an antiferromagnetic exchange for 1, though the magnitude is overestimated (J(DFT) = -71 cm(-1)). Calculations reveal that the antiferromagnetic interaction essentially stems from the Mn(d(x(2)-y(2)))-Cu(d(x(2)-y(2))) interaction. The computed single-ion anisotropy and cluster anisotropy also correlates well with experiment. A larger cluster anisotropy for the S = 3/2 state compared to the single-ion anisotropy of Mn(III) is rationalised on the basis of orbital mixing and various contributions that arise due to the spin-orbit interaction.