Fixation of carbon dioxide by macrocyclic lanthanide(III) complexes under neutral conditions producing self-assembled trimeric carbonato-bridged compounds with µ3222 bonding

Bag, Pradip ; Dutta, Supriya ; Biswas, Papu ; Maji, Swarup Kumar ; Flörke, Ulrich ; Nag, Kamalaksha (2012) Fixation of carbon dioxide by macrocyclic lanthanide(III) complexes under neutral conditions producing self-assembled trimeric carbonato-bridged compounds with µ3222 bonding Dalton Transactions, 41 (12). pp. 3414-3423. ISSN 0300-9246

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Official URL: http://pubs.rsc.org/en/Content/ArticleLanding/2012...

Related URL: http://dx.doi.org/10.1039/C2DT12221A

Abstract

A series of mononuclear lanthanide(III) complexes [Ln(LH2)(H2O)3Cl](ClO4)2 (Ln = La, Nd, Sm, Eu, Gd, Tb, Lu) of the tetraiminodiphenolate macrocyclic ligand (LH2) in 95:5 (v/v) methanol-water solution fix atmospheric carbon dioxide to produce the carbonato-bridged trinuclear complexes [{Ln(LH2)(H2O)Cl}33-CO3)](ClO4)4·nH2O. Under similar conditions, the mononuclear YIII complex forms the dimeric compound [{Y(LH2)(H2O)Cl}(µ2-CO3){Y(LH2)(H2O)2}](ClO4)3·4H2O. These complexes have been characterized by their IR and NMR (1H, 13C) spectra. The X-ray crystal structures have been determined for the trinuclear carbonato-bridged compounds of NdIII, GdIII and TbIII and the dinuclear compound of YIII. In all cases, each of the metal centers are 8-coordinate involving two imine nitrogens and two phenolate oxygens of the macrocyclic ligand (LH2) whose two other imines are protonated and intramolecularly hydrogen-bonded with the phenolate oxygens. The oxygen atoms of the carbonate anion in the trinuclear complexes are bonded to the metal ions in tris-bidentate µ3222 fashion, while they are in bis-bidentate µ222 mode in the YIII complex. The magnetic properties of the GdIII complex have been studied over the temperature range 2 to 300 K and the magnetic susceptibility data indicate a very weak antiferromagnetic exchange interaction (J = -0.042 cm-1) between the GdIII centers (S = 7/2) in the metal triangle through the carbonate bridge. The luminescence spectral behaviors of the complexes of SmIII, EuIII, and TbIII have been studied. The ligand LH2 acts as a sensitizer for the metal ions in an acetonitrile-toluene glassy matrix (at 77 K) and luminescence intensities of the complexes decrease in the order Eu3+ > Sm3+ > Tb3+.

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ID Code:86965
Deposited On:14 Mar 2012 07:33
Last Modified:14 Mar 2012 07:33

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