title: Interactions between alkaline earth cations and oxo ligands. DFT study of the affinity of the Mg²+ cation for phosphoryl ligands.
abstract: DFT (B3LYP/6-31+G(d)) calculations of Mg(2+) affinities for a set of phosphoryl ligands were performed. Two types of ligands were studied: a set of trivalent [O = P(R)] and a set of pentavalent phosphoryl ligands [O = P(R)(3)] (R = H, F, Cl, Br, OH, OCH(3), CH(3), CN, NH(2) and NO(2)), with R either bound directly to the phosphorus atom or to the para position of a phenyl ring. The affinity of the Mg(2+) cation for the ligands was quantified by means of the enthalpy for the substitution of one water molecule in the [Mg(H(2)O)(6)](2+) complex for a ligand. The enthalpy of substitution was correlated with electronic and geometric parameters. Electron-donor groups increase the interaction between the cation and the ligand, while electron-acceptor groups decrease the interaction enthalpy.
authors.affiliation: Programa de Pós-Graduação em Química, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, s/n, 24020-141 Niterói, RJ, Brazil.
authors.forename: Leonardo Moreira
authors.initials: LM
authors.lastname: da Costa
authors.forename: José Walkimar
authors.initials: JW
authors.lastname: de Mesquita Carneiro
authors.forename: Lilian Weitzel Coelho
authors.initials: LW
authors.lastname: Paes
mesh_terms: D002412:Cations / Q000737:chemistry*; D008024:Ligands; D008274:Magnesium / Q000737:chemistry*; D008673:Metals, Alkaline Earth / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D002412:Cations; D008024:Ligands; D008673:Metals, Alkaline Earth; D014867:Water; D008274:Magnesium