Density functional theory investigation of the binding interactions between phosphoryl, carbonyl, imino, and thiocarbonyl ligands and the pentaaqua nickel(II) complex: Coordination affinity and associated parameters

Authors

  • Leonardo M. da Costa,

    1. Centro Universitário Estadual da Zona Oeste, Pharmacy Division Rua Manuel Caldeira de Alvarenga, Campo Grande, RJ, Brazil
    2. Programa de Pós-Graduação em Química and Departamento de Química Inorgânica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, Niterói, RJ, Brazil
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  • Stanislav R. Stoyanov,

    1. National Institute for Nanotechnology, National Research Council of Canada, Edmonton, Alberta, Canada
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  • Raimundo N. Damasceno,

    1. Núcleo de Estudos em Biomassa e Gerenciamento de Águas, Universidade Federal Fluminense, Outeiro de São João Batista, Niterói, RJ, Brazil
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  • José Walkimar de M. Carneiro

    Corresponding author
    1. Programa de Pós-Graduação em Química and Departamento de Química Inorgânica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, Niterói, RJ, Brazil
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Abstract

Density Functional Theory (UB3LYP/6-311++G(d,p)) calculations of the affinity of the pentaaqua nickel(II) complex for a set of phosphoryl [O[DOUBLE BOND]P(H)(CH3)(PhR)], imino [HN[DOUBLE BOND]C(CH3)(PhR)], thiocarbonyl [S[DOUBLE BOND]C(CH3)(PhR)] and carbonyl [O[DOUBLE BOND]C(CH3)(PhR)] ligands were performed, where R[DOUBLE BOND]NH2, OCH3, OH, CH3, H, Cl, CN, and NO2 is a substituent at the para-position of a phenyl ring.The affinity of the pentaaqua nickel(II) complex for these ligands was analized and quantified in terms of interaction enthalpy (ΔH), Gibbs free energy (ΔG298), geometric and electronic parameters of the resultant octahedral complexes. The ΔH and ΔG298 results show that the ligand coordination strength increases in the following order: carbonyl < thiocarbonyl < imino < phosphoryl. This coordination strength order is also observed in the analysis of the metal-ligand distances and charges on the ligand atom that interacts with the Ni(II) cation. The electronic character of the substituent R is the main parameter that affects the strength of the metal-ligand coordination. Ligands containing electron-donating groups (NH2, OCH3, OH) have more exothermic ΔH and ΔG298 than ligands with electron-withdrawing groups (Cl, CN, NO2). The metal-ligand interaction decomposed by means of the energy decomposition analysis (EDA) method shows that the electronic character of the ligand modulates all the components of the metal-ligand interaction. The absolute softness of the free ligands is correlated with the covalent contribution to the instantaneous interaction energy calculated using the EDA method. © 2013 Wiley Periodicals, Inc.

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