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Siddiqi Z.A.,Coordination Chemistry Research Group | Khalid M.,Coordination Chemistry Research Group | Kumar S.,Coordination Chemistry Research Group | Shahid M.,Coordination Chemistry Research Group | Noor S.,Coordination Chemistry Research Group
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2010

Spectral and molecular model computations on homo-dinuclear complexes [M2L2(H2O)2Cl2] [L = 1-(salicylaldeneamino)-3-hydroxypropane, M = Cr3+, Mn3+, Fe3+, Co3+, Ni3+ or Cu3+] are consistent with a distorted hexa-coordinate geometry. X-band EPR spectral data indicated a rhombic distortion around Cu(II) ion. Magnetic moment and 57Fe Mössbauer data confirmed a high-spin state electronic configuration (t2g 3eg 2, S = 5/2) and asymmetric ligand environment around Fe(III) with nuclear transitions Fe(±3/2 → 1/2) exhibiting Kramer's double degeneracy. The neighboring Fe(III) nuclei in the homo-dinuclear species are antiferromagnetically coupled. © 2009 Elsevier B.V. All rights reserved.


Siddiqi Z.A.,Coordination Chemistry Research Group | Shahid M.,Coordination Chemistry Research Group | Khalid M.,Coordination Chemistry Research Group | Noor S.,Coordination Chemistry Research Group | Kumar S.,Coordination Chemistry Research Group
Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy | Year: 2010

The newly prepared homo-bimetallic complexes [M2(imda)2(H2O)4], [M2(imda)2(Bipy)2] (M = Co, Ni or Cu) and [Fe2(imda)2(H2O)3Cl] (H2imda = iminodiacetic acid and Bipy = 2,2′-bipyridine) have been studied employing IR, FAB-mass, 1H and 13C NMR, EPR and ligand field spectra, which indicated a high-spin state of metal ion with hexa-coordinate environment. 57Fe Mössbauer data of the homo-bimetallic complex [Fe2(imda)2(H2O)3Cl] confirm a high-spin configuration with Fe (±3/2 → 1/2) nuclear transitions and the presence of Kramer's double degeneracy. At RT, the spin-spin interactions of the neighbouring nuclei (Fe3+-Fe3+ = S5/2-S5/2) are anti-ferromagnetically coupled. However, at LNT, the complex acquires a mixed-valent [FeIII-FeII] composition corroborated from the X-band EPR data. CV studies indicated the presence of quasi-reversible redox CuII/I, CuII/III, FeIII/II, FeIII/I and FeII/I couples. © 2009 Elsevier B.V. All rights reserved.

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