The reactions of pyridine-2-carbaldehyde with aminoalcohols N-(2-hydroxyethyl) ethylenediamine and 2-(3-aminopropylamino) ethanol in presence of (CdX2)-X-II (X=Cl, Br, I) have been investigated. Structure analyses reveal that four complexes, namely [Cd-2(L-1)(2)(Br)4] (2), [Cd(L-1)(I)(2)] (3), [Cd(L-1)(Br)2] (5) and [Cd(L-2)(I)(2)] (6) are formed with the expected Schiff-base ligands (E)-2-(2-(pyridin-2-ylmethyleneamino) ethylamino) ethanol (L1) and (E)-2-(3-(pyridin-2-ylmethyleneamino) propylamino) ethanol (L2). Interestingly, when X= Cl two dinuclear complexes of general formula [Cd2(L1C/L2C)2(Cl)4](complex 1 and 4, respectively) have been structurally characterized, where the ligands are no longer Schiff-bases but contain an imidazolidine/hexahydro-pyrimidine cyclic part instead [L1C = 2-(2-Pyridin-2-yl-imidazolidin-1-yl)-ethanol and L2C = 2-(2-Pyridin-2-yl-tetrahydro-pyrimidin-1-yl)-ethanol]. In order to understand whether the solid state structure is retained in solution various NMR analysis like 1H, 13CNMR and DEPT-135 have been performed. When X= I, the equilibrium is shifted towards the formation of the Schiff-base ligands, thus complexes 3 and 6 are obtained as sole products. However, with X= Br or Cl, a mixture of products is present, comprising complexes containing both Schiff-bases as well as cyclized ligands. DFT calculations have been performed to rationalize the influence of the halide ligands on the reactivity of the Schiff-base and the formation of the cyclized ligand.

Halide Ion Mediated Aldehyde-Amine Condensation Leading to Schiff-base and Cyclized Non-Schiff-base Ligand Complexes of CdII: A Combined Experimental and Theoretical Investigation / Purkait, Suranjana; Chakraborty, Prateeti; Bauzá, Antonio; Frontera, Antonio; Massera, Chiara; Das, Debasis. - In: CHEMISTRYSELECT. - ISSN 2365-6549. - 1:15(2016), pp. 4539-4549. [10.1002/slct.201600967]

Halide Ion Mediated Aldehyde-Amine Condensation Leading to Schiff-base and Cyclized Non-Schiff-base Ligand Complexes of CdII: A Combined Experimental and Theoretical Investigation

MASSERA, Chiara;
2016

Abstract

The reactions of pyridine-2-carbaldehyde with aminoalcohols N-(2-hydroxyethyl) ethylenediamine and 2-(3-aminopropylamino) ethanol in presence of (CdX2)-X-II (X=Cl, Br, I) have been investigated. Structure analyses reveal that four complexes, namely [Cd-2(L-1)(2)(Br)4] (2), [Cd(L-1)(I)(2)] (3), [Cd(L-1)(Br)2] (5) and [Cd(L-2)(I)(2)] (6) are formed with the expected Schiff-base ligands (E)-2-(2-(pyridin-2-ylmethyleneamino) ethylamino) ethanol (L1) and (E)-2-(3-(pyridin-2-ylmethyleneamino) propylamino) ethanol (L2). Interestingly, when X= Cl two dinuclear complexes of general formula [Cd2(L1C/L2C)2(Cl)4](complex 1 and 4, respectively) have been structurally characterized, where the ligands are no longer Schiff-bases but contain an imidazolidine/hexahydro-pyrimidine cyclic part instead [L1C = 2-(2-Pyridin-2-yl-imidazolidin-1-yl)-ethanol and L2C = 2-(2-Pyridin-2-yl-tetrahydro-pyrimidin-1-yl)-ethanol]. In order to understand whether the solid state structure is retained in solution various NMR analysis like 1H, 13CNMR and DEPT-135 have been performed. When X= I, the equilibrium is shifted towards the formation of the Schiff-base ligands, thus complexes 3 and 6 are obtained as sole products. However, with X= Br or Cl, a mixture of products is present, comprising complexes containing both Schiff-bases as well as cyclized ligands. DFT calculations have been performed to rationalize the influence of the halide ligands on the reactivity of the Schiff-base and the formation of the cyclized ligand.
Halide Ion Mediated Aldehyde-Amine Condensation Leading to Schiff-base and Cyclized Non-Schiff-base Ligand Complexes of CdII: A Combined Experimental and Theoretical Investigation / Purkait, Suranjana; Chakraborty, Prateeti; Bauzá, Antonio; Frontera, Antonio; Massera, Chiara; Das, Debasis. - In: CHEMISTRYSELECT. - ISSN 2365-6549. - 1:15(2016), pp. 4539-4549. [10.1002/slct.201600967]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2827779
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