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

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Title Switching the orientation of Jahn-Teller axes in oxime-based Mn-III dimers and its effect upon magnetic exchange: a combined experimental and theoretical study
 
Creator COMAR, P
RAJESHKUMAR, T
NICHOL, GS
PITAK, MB
COLES, SJ
RAJARAMAN, G
BRECHIN, EK
 
Subject SINGLE-MOLECULE MAGNETS
TRANSITION-METAL-COMPLEXES
GAUSSIAN-BASIS SETS
FERROMAGNETIC EXCHANGE
COUPLING-CONSTANTS
MN-2(III) DIMER
GROUND-STATE
ATOMIC-SCALE
CLUSTERS
INTERFERENCE
 
Description A family of Mn-III dimers of general formula [Mn-2(III)(R-sao)(2)(dpa)(2)](ClO4)(2) (1-5) has been synthesised using derivatised phenolic oximes (R-saoH(2), where R = H, Me, Et, Ph) in combination with di-(2-picolyl)-amine (dpa). Their structures reveal a double-oxime bridged [Mn-III(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.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2016-01-15T07:11:57Z
2016-01-15T07:11:57Z
2015
 
Type Article
 
Identifier DALTON TRANSACTIONS, 44(46)19805-19811
1477-9226
1477-9234
http://dx.doi.org/10.1039/c5dt03615a
http://dspace.library.iitb.ac.in/jspui/handle/100/18018
 
Language en