Record Details

Magnetic Exchange Interactions and Magneto-Structural Correlations in Heterobridged mu-Phenoxo-mu(1,1)-Azide Dinickel(II) Compounds: A Combined Experimental and Theoretical Exploration

DSpace at IIT Bombay

View Archive Info
 
 
Field Value
 
Title Magnetic Exchange Interactions and Magneto-Structural Correlations in Heterobridged mu-Phenoxo-mu(1,1)-Azide Dinickel(II) Compounds: A Combined Experimental and Theoretical Exploration
 
Creator SASMAL, S
HAZRA, S
KUNDU, P
DUTTA, S
RAJARAMAN, G
SANUDO, EC
MOHANTA, S
 
Subject SINGLE-MOLECULE-MAGNET
TRANSITION-METAL-COMPLEXES
GAUSSIAN-BASIS SETS
SPIN GROUND-STATE
FERROMAGNETIC INTERACTIONS
POLYNUCLEAR COMPLEXES
COPPER(II) COMPLEXES
BINUCLEAR COMPLEXES
DI-2-PYRIDYL KETONE
COUPLING-CONSTANTS
 
Description This investigation presents the syntheses, crystal structures, magnetic properties, and density functional theoretical modeling of magnetic behavior of two heterobridge mu-phenoxo-mu(1,1)-azido dinickel(II) compounds [Ni(2)(II)(L(1))(2)(mu(1,1)-N(3))(N(3))(H(2)O)]center dot CH(3)CH(2)OH (1) and [Ni(2)(II)(L(2))(2)(mu(1,1)-N(3))(CH(3)CN)(H(2)O)] (ClO(4))center dot(H(2)O center dot CH(3)CN (2), where HL(1) and HL(2) are the [1 + 1] condensation products of 3-methoxysalicylaldehyde and 1-(2-aminoethyl)-piperidine (for HL1)/4(2-aminoethyl)-morpholine (for HL(2)), along with density functional theoretical magneto-structural correlations of mu-phenoxo-mu(1,1)-azido dinickel(II) systems. Compounds 1 and 2 crystallize in orthorhombic (space group Pbca) and monoclinic (space group P2(1)/c) systems, respectively. The coordination environments of both metal centers are distorted octahedral. The variable-temperature (2-300 K) magnetic susceptibilities at 0.7 T of both compounds have been measured. The interaction between the metal centers is moderately ferromagnetic; J = 16.6 cm(-1), g = 2.2, and D = 7.3 cm(-1) for 1 and J = 16.92 cm(-1), g = 2.2, and D(Ni1) = D(Ni2) = 6.41 cm(-1) for 2. Broken symmetry density functional calculations of exchange interaction have been performed on complexes 1 and 2 and provide a good numerical estimate of J values (15.8 cm(-1) for 1 and 15.35 cm(-1) for 2) compared to experiments. The role of Ni-N bond length asymmetry on the magnetic coupling has been noted by comparing the structures and J valnes of complexes 1 and 2 together with previously published dimers 3 (Eur. J. Inorg. Chem. 2009, 4982), 4 (Inorg. Chem. 2004, 43, 2427), and 5 (Dalton Trans. 2008, 6539). Our extensive DFT calculations reveal an important clue to the mechanism of coupling where the orientation of the magnetic orbitals seems to differ with asymmetry in the Ni-N bond lengths. This difference in orientation leads to a large change in the overlap integral between the magnetic orbitals and thus the magnetic coupling. DFT calculations have also been extended to develop several magneto-structural correlations in this type of complexes and the correlation aim to focus on the asymmetry of the Ni-N bond lengths reveal that the asymmetry plays a proactive role in governing the magnitude of the coupling. From a completely symmetric Ni-N bond length, two behaviors have been noted: with a decrease in bond length there is an increase in the ferromagnetic coupling, while an increase in the bond lengths leads to a decrease in ferromagnetic interaction. The later correlation is supported by experiments. The magnetic, properties of 1, 2, and three previously reported related compounds have been discussed in light of the structural parameters and also in light of the theoretical correlations determined here.
 
Publisher AMER CHEMICAL SOC
 
Date 2012-06-26T08:51:43Z
2012-06-26T08:51:43Z
2011
 
Type Article
 
Identifier INORGANIC CHEMISTRY,50(15)7257-7267
0020-1669
http://dx.doi.org/10.1021/ic200833y
http://dspace.library.iitb.ac.in/jspui/handle/100/14228
 
Language English