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Structural Characterization of an Enantiopure Hydroxo-Bridged Binucleariron(III) Complex with Empty One-Dimensional Helical Channels

Alam, Akhtarul Md and Nethaji, Munirathinum and Ray, Manabendra (2005) Structural Characterization of an Enantiopure Hydroxo-Bridged Binucleariron(III) Complex with Empty One-Dimensional Helical Channels. In: Inorganic Chemistry, 44 (5). pp. 1302-1308.

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Abstract

A H-bond capable chiral tetradentate ligand, $Fe^3^+$, and acetate ion assembles into a hydroxo-bridged binuclear complex with the formula $[Fe^I^I^I_2(\mu-OH)(\mu-OAc)(S-L)_2]•4H_2O$ (1) where $H_2S-L$ = S-2-(2-hydroxy-benzylamino)-3-(1$H$-imidazol-4-yl)-propionic acid. The crystal of 1 contains right-handed one-dimensional (1D) helical channels with 7.3-9.8 Å diameter. A similar reaction with a ligand having opposite chirality forms the complex with left-handed helical channels (1a). Heating the crystals of 1 at 95 C under reduced pressure selectively removes three waters from the channel forming an enantiopure porous crystal with empty channels (solvent accessible voids 18% v/v). Intermolecular hydrogen bonding between the imidazole N-H and phenolate oxygen in 1-2 forms a $C_6$ symmetric helix with bridging hydroxo groups pointing inside the channels. All the H-bond capable atoms in the ligand along with one water molecule form an extended H-bonded network throughout the crystal. Exposing the empty channels of 2 to iodine vapor indicates partial filling of the channels with iodine. Crystal data for 1•4$H_2O$ include the following: hexagonal, P61, a = b = 13.164(3) Å, c = 36.305 (11) Å, = \alpha = \beta = 90 ,\gamma = 120 , Z = 6, R1 = 0.0387, wR2 = 0.0842. Crystal data for 1a•2$H_2O$ include the following: hexagonal, P65, a = b = 13.151(4) Å, c = 36.558(2) Å, \alpha = \beta = 90 , \gamma = 120 , Z = 6, R1 = 0.0416, wR2 = 0.1190. Crystal data for 2•$H_2O$ include the following: hexagonal, P61, a = b = 13.160(7) Å, c = 36.559 (4) Å, \alpha = \beta = 90 , \gamma = 120 , Z = 6, R1 = 0.0574, wR2 = 0.1423.

Item Type: Journal Article
Additional Information: The copyright for this article belongs to American Chemical Society.
Department/Centre: Division of Chemical Sciences > Inorganic & Physical Chemistry
Date Deposited: 01 Feb 2007
Last Modified: 19 Sep 2010 04:18
URI: http://eprints.iisc.ernet.in/id/eprint/3029

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