Use of 2-pyrimidineamidoxime to generate polynuclear homo-/heterometallic assemblies: synthesis, crystal structures and magnetic study with theoretical investigations on the exchange mechanism

Gole, Bappaditya and Chakrabarty, Rajesh and Mukherjee, Sandip and Song, You and Mukherjee, Partha Sarathi (2010) Use of 2-pyrimidineamidoxime to generate polynuclear homo-/heterometallic assemblies: synthesis, crystal structures and magnetic study with theoretical investigations on the exchange mechanism. In: Dalton Transactions (2003), 39 (41). pp. 9766-9778.

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Abstract

Three new transition metal complexes using 2-pyrimidineamidoxime (pmadH(2)) as multidentate chelating and/or bridging ligand have been synthesized and characterized. The ligand pmadH(2) has two potential bridging functional groups mu-O and mu-(N-O)] and consequently shows several coordination modes. While a polymeric 1D Cu-II complex Cu(pmadH(2))(2)(NO3)](NO3) (1) was obtained upon treatment of Cu(NO3)(2)center dot 3H(2)O with pmadH(2) at room temperature in the absence of base, a high temperature reaction in the presence of base yielded a tetranuclear Cu-II-complex Cu-4(pmad)(2)(pmadH)(2)(NO3)](NO3)(H2O) (2). One of the Cu-II centers is in a square pyramidal environment while the other three are in a square planar geometry. Reaction of the same ligand with an equimolar mixture of both Cu(NO3)(2)center dot 3H(2)O and NiCl2 center dot 6H(2)O yielded a tetranuclear heterometallic (Cu2Ni2II)-Ni-II complex Cu2Ni2(pmad)(2)(pmadH)(2)Cl-2]center dot H2O (3) containing both square planar (Ni-II) and square pyramidal (Cu-II) metal centers. Complexes 1-3 represent the first examples of polynuclear metal complexes of 2-pyrimidineamidoxime. The analysis of variable temperature magnetic susceptibility data of 2 reveals that both ferromagnetic and antiferromagnetic interactions exist in this complex (J(1) = +10.7 cm(-1) and J(2) = -2.7 cm(-1) with g = 2.1) leading to a resultant ferromagnetic behavior. Complex 3 shows expected antiferromagnetic interaction between two Cu-II centers through -N-O- bridging pathway with J(1) = -3.4 cm(-1) and g = 2.08. DFT calculations have been used to corroborate the magnetic results.

Item Type:	Journal Article
Publication:	Dalton Transactions (2003)
Publisher:	Royal Society of Chemistry
Additional Information:	Copyright of this article belongs to Royal Society of Chemistry.
Department/Centre:	Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited:	04 Nov 2010 11:32
Last Modified:	04 Nov 2010 11:32
URI:	http://eprints.iisc.ac.in/id/eprint/33565

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