Template Syntheses of Copper(II) Complexes from Arylhydrazones of Malononitrile and their Catalytic Activity towards Alcohol Oxidations and the Nitroaldol Reaction: Hydrogen Bond-Assisted Ligand Liberation and E/Z Isomerisation

Authors

  • Dr. Maximilian N. Kopylovich,

    Corresponding author
    1. Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
    • Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
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  • Dr. Archana Mizar,

    1. Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
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  • Dr. M. Fátima C. Guedes da Silva,

    Corresponding author
    1. Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
    2. Universidade Lusófona de Humanidades e Tecnologias, ULHT Lisbon, Campo Grande 376, 1749-024 Lisbon (Portugal)
    • Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
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  • Dr. Tatiana C. O. Mac Leod,

    1. Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
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  • Dr. Kamran T. Mahmudov,

    1. Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
    2. Baku State University, Department of Chemistry, Z. Xalilov Str. 23, Az 1148 Baku (Azerbaijan)
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  • Prof. Armando J. L. Pombeiro

    Corresponding author
    1. Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
    • Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049–001 Lisbon (Portugal)
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Abstract

A one-pot template condensation of 2-(2-(dicyanomethylene)hydrazinyl)benzenesulfonic acid (H2L1, 1) or 2-(2-(dicyanomethylene)hydrazinyl)benzoic acid (H2L2, 2) with methanol (a), ethylenediamine (b), ethanol (c) or water (d) on copper(II), led to a variety of metal complexes, that is, mononuclear [Cu(H2O)2O1N2 L1a] (3) and [Cu(H2O)(κO1N3 L1b)] (4), tetranuclear [Cu4(1 κO1N2:2 κO1 L2a)3-(1 κO1, κN2:2 κO2 L2a)] (5), [Cu2(H2O)(1 κO1, κN2:2 κO1 L2c)-(1 κO1,1 κN2:2 κO1,2 κN1- L2c)]2 (6) and [Cu2(H2O)2O1N2- L1dd)-(1 κO1N2:2 κO1 L1dd)(μ-H2O)]2 2 H2O (7⋅2 H2O), as well as polymer- ic [Cu(H2O)(κO1,1 κN2:2 κN1 L1c)]n (8) and [Cu(NH2C2H5)(κO1,1 κN2:2 κN1L2a)]n (9). The ligands 2-SO3H-C6H4-(NH)N[DOUBLE BOND]C{(CN)[C(NH2)-([DOUBLE BOND]NCH2CH2NH2)]} (H2L1b, 10), 2-CO2H-C6H4-(NH)N[DOUBLE BOND]{C(CN)[C(OCH3)-([DOUBLE BOND]NH)]} (H2L2a, 11) and 2-SO3H-C6H4-(NH)N[DOUBLE BOND]C{C([DOUBLE BOND]O)-(NH2)}2 (H2L1dd, 12) were easily liberated upon respective treatment of 4, 5 and 7 with HCl, whereas the formation of cyclic zwitterionic amidine 2-(SO3)[BOND]C6H4[BOND]N[DOUBLE BOND]NC([BOND]C[DOUBLE BOND](NH+)CH2CH2NH)([DOUBLE BOND]CNHCH2CH2NH) (13) was observed when 1 was treated with ethylenediamine. The hydrogen bond-induced E/Z isomerization of the (HL1d) ligand occurs upon conversion of [{Na(H2O)2(μ-H2O)2}(HL1d)]n (14) to [Cu(H2O)6][HL1d]22 H2O (15) and [{CuNa(H2O)-(κN1,1 κO2:2 κO1 L1d)2}K0.5(μ-O)2]nH2O (16). The synthesized complexes 39 are catalyst precursors for both the selective oxidation of primary and secondary alcohols (to the corresponding carbonyl compounds) and the following diastereoselective nitroaldol (Henry) reaction, with typical yields of 80–99 %.

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