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Co(II) and Cr(III) complexes of formate-formamide mixed ligands: synthesis, structures, single crystal-to-single crystal transformation and magnetic behaviour

Sengupta, Oindrila and Song, You and Mukherjee, Partha Sarathi (2009) Co(II) and Cr(III) complexes of formate-formamide mixed ligands: synthesis, structures, single crystal-to-single crystal transformation and magnetic behaviour. In: Dalton transactions, t (46). pp. 10343-10352.

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Abstract

Solvothermal treatment of an equimolar mixture of Co(NO3)(2)center dot 6H(2)O, HCONH2 and NaN3 in MeOH at 100 degrees C yielded a three-dimensional NaCl type network Co(HCOO)(2)(HCONH2)(2) center dot HCONH2 (1a) containing formamides in the pores of the structure. Solvated pink 1a undergoes single crystal-to-single crystal (SCSC) transformation at 215 degrees C to form the desolvated dark brown product Co(HCOO)(2)-( HCONH2)(2) (1b) with the retention of the original framework. Reversible single crystal-to-single crystal transformation of 1b (brown) to 1a (pink) in the presence of excess formamide was also established at room temperature. The coordination environment around Co(II) in both 1a and 1b is octahedral with a CoN2O4 coordination composition. A similar reaction replacing Co(II) by Cr(III) produced a heterometallic 3D extended network Na[Cr(HCOO)(4)(HCONH2)(2)]center dot 2H(2)O (2a) at 100 degrees C. An increase in reaction temperature to 150 degrees C produced a simple mononuclear complex Cr(HCOO)(3)(HCONH2)(3) center dot 3H(2)O (2b). Variable temperature magnetic studies revealed the presence of a canting phenomena in both 1a and 1b, and hysteresis loop in the field dependent magnetisation plot at 2 K whereas complex 2a is simply paramagnetic in nature.

Item Type: Journal Article
Additional Information: copyright of this article belongs to Royal soc chemistry.
Keywords: Metal-organic framework;molecular host frameworks;double-zigzag chain;coordination polymer;canted antiferromagnetism;hydrothermal synthesis; 2-dimensional network; weak ferromagnetism; ground-state; solid-state
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 11 Dec 2009 06:27
Last Modified: 19 Sep 2010 05:53
URI: http://eprints.iisc.ernet.in/id/eprint/25168

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