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From antiferromagnetic to ferromagnetic exchange in a family of oxime-based Mn-III dimers: a magneto-structural study

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Title From antiferromagnetic to ferromagnetic exchange in a family of oxime-based Mn-III dimers: a magneto-structural study
 
Creator BARROS, WP
INGLIS, R
NICHOL, GS
RAJESHKUMAR, T
RAJARAMAN, G
PILIGKOS, S
STUMPF, HO
BRECHIN, EK
 
Subject SINGLE-MOLECULE MAGNETS
TRANSITION-METAL-COMPLEXES
TARGETED STRUCTURAL DISTORTION
THEORETICAL EXPLORATION
POLYNUCLEAR COMPLEXES
PHYSICAL-PROPERTIES
COUPLING-CONSTANTS
CRYSTAL-STRUCTURES
NI(II) COMPLEXES
MN-2(III) DIMER
 
Description The reaction of Mn(ClO4)(2)center dot 6H(2)O, a derivatised phenolic oxime (R-saoH(2)) and the ligand tris(2-pyridylmethyl)amine (tpa) in a basic alcoholic solution leads to the formation of a family of cluster compounds of general formula [(Mn2O)-O-III(R-sao)(tpa)(2)](ClO4)(2) (1, R = H; 2, R = Me; 3, R = Et; 4, R = Ph). The structure is that of a simple, albeit asymmetric, dimer of two Mn-III ions bridged through one mu-O2- ion and the -N-O- moiety of the phenolic oxime. Magnetometry reveals that the exchange interaction between the two MnIII ions in complexes 1, 3 and 4 is antiferromagnetic, but that for complex 2 is ferromagnetic. A theoretically developed magneto-structural correlation reveals that the dominant structural parameter influencing the sign and magnitude of the pairwise interaction is the dihedral Mn-O-N-Mn (torsion) angle. A linear correlation is found, with the magnitude of J varying significantly as the dihedral angle is altered. As the torsion angle increases the AF exchange decreases, matching the experimentally determined data. DFT calculations reveal that the (dyz)vertical bar pi vertical bar d(yz) interaction decreases as the dihedral angle increases leading to ferromagnetic coupling at larger angles.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2014-10-17T05:05:23Z
2014-10-17T05:05:23Z
2013
 
Type Article
 
Identifier DALTON TRANSACTIONS, 42(47)16510-16517
1477-9226
1477-9234
http://dx.doi.org/10.1039/c3dt52009a
http://dspace.library.iitb.ac.in/jspui/handle/100/16022
 
Language en