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Synthesis, crystal structure and magnetic properties of quasi-linear tetranuclear copper(II) Schiff base complexes formed by covalent linkage of asymmetrically dibridged dicopper(II) units

Mukherjee, Arindam and Saha, Manas K and Rudra, Indranil and Ramasesha, Suryanarayanasastry and Nethaji, Munirathinam and Chakravarty, Akhil R (2004) Synthesis, crystal structure and magnetic properties of quasi-linear tetranuclear copper(II) Schiff base complexes formed by covalent linkage of asymmetrically dibridged dicopper(II) units. In: Inorganica Chimica Acta, 357 (4). pp. 1077-1082.

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Abstract

Alkoxo-phenoxo bridged tetranuclear copper(II) complexes $[Cu_4L_2(O_2CC_6H_4-p-OH)_2]$ (1) and $[Cu_4L_2(O_2CC_6H_4-o-OH)_2] (2)$ containing pentadentate Schiff base ligand N,N'-(2-hydroxypropane-1,3-diyl)bis(salicylaldimine) $(H_3L)$ are prepared and structurally characterized. Crystal structures of the complexes show the covalent linkage between two $\{Cu_2L(O_2CR)\}($R=$C_6H_4-p-OH,C_6H_4-o-OH)$ units through the phenoxo atoms of the Schiff base ligand showing axial/equatorial bonding modes. The Cu(1)–O(2)– Cu(2) alkoxo bridge angle is $131^o$ in 1 and 2. The pendant ortho- and para- OH groups of the three-atom bridging carboxylate ligands show no apparent bonding interactions with the metal or other group(s). The complexes show a d–d band near 635 nm in $CH_2Cl_2$. Variable temperature magnetic susceptibility measurements in the temperature range 300–18 K show antiferromagnetically coupled spin system. A theoretical fit of the magnetic data using exchange parameters $J_1$ and $J_2$ for the intradimer and interdimer units of the quasi-linear tetrameric core gave values as: $J_1 = -132, J_2 = -72 cm^{-1}$ for 1 and $J_1 = -167, J_2 = -67 cm^{-1}$ for 2.

Item Type: Journal Article
Additional Information: The copyright belongs to Elsevier.
Keywords: Copper complexes;Crystal structures;Pentadentate Schiff base;Magnetic properties
Department/Centre: Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 27 May 2006
Last Modified: 19 Sep 2010 04:27
URI: http://eprints.iisc.ernet.in/id/eprint/6899

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