Issue 46, 2015

Switching the orientation of Jahn–Teller axes in oxime-based MnIII dimers and its effect upon magnetic exchange: a combined experimental and theoretical study

Abstract

A family of MnIII dimers of general formula [MnIII2(R-sao)2(dpa)2](ClO4)2 (1–5) has been synthesised using derivatised phenolic oximes (R-saoH2, where R = H, Me, Et, Ph) in combination with di-(2-picolyl)-amine (dpa). Their structures reveal a double-oxime bridged [MnIII(NO)]2 magnetic core in which the Jahn–Teller axes lie perpendicular to the bridging plane, in contrast to two previously reported family members (6, 7). The switch in the orientation of the Jahn–Teller axes is enforced through the use of the chelating ligand which is present in 1–5 and absent in 6–7. Dc magnetic susceptibility measurements reveal that the exchange interactions between the MnIII metal centres in 1–5 are antiferromagnetic in contrast to that observed for 6 and 7 which are ferromagnetic. DFT calculations performed on complexes 1–6 reproduce both the sign and strength of the J values found experimentally. Molecular orbital analysis unlocks a common mechanism of magnetic coupling based upon the orientation of the Jahn–Teller axis, with the magneto-structural correlation also dependent upon the Mn–N–O–Mn angles – with ferromagnetic interactions at smaller dihedral angles.

Graphical abstract: Switching the orientation of Jahn–Teller axes in oxime-based MnIII dimers and its effect upon magnetic exchange: a combined experimental and theoretical study

Supplementary files

Article information

Article type
Paper
Submitted
15 Sep 2015
Accepted
07 Oct 2015
First published
12 Oct 2015
This article is Open Access
Creative Commons BY license

Dalton Trans., 2015,44, 19805-19811

Author version available

Switching the orientation of Jahn–Teller axes in oxime-based MnIII dimers and its effect upon magnetic exchange: a combined experimental and theoretical study

P. Comar, T. Rajeshkumar, G. S. Nichol, M. B. Pitak, S. J. Coles, G. Rajaraman and E. K. Brechin, Dalton Trans., 2015, 44, 19805 DOI: 10.1039/C5DT03615A

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