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|Type:||Artigo de periódico|
|Title:||Solid state and solution characterization of a new dinuclear nickel (II) complex: The search for synthetic models for urease|
|Abstract:||The X-ray molecular structure and, magnetic, and spectroscopic properties, as well as the analysis of the structural behavior in solution of a novel nickel (II) complex [Ni-2(HBPClNOL)(2)(OAc)ClO4) 1 are reported. Complex 1 was prepared by the reaction between the ligand H2BPCINOL (N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2-hydroxy)]propylamine), [Ni(H2O)(6)](ClO4)(2) and sodium acetate. Magnetic measurements indicate the presence of a weak antiferromagnefic coupling between the Ni(II) ions in 1, resulting in J = -4.23 cm(-1). Mass spectrometric characterization of the complex 1 was also performed via ESI-MS and ESI-MS/MS experiments and reveals that there are at least three different cations in solution, one mononuclear [Ni(H2BPClNOL)(OAc)](+) and two dinuclear [Ni-2(HBPClNOL)(2)(OAc)](+) and [Ni-2(HBPClNOL)(2)(ClO4)](+) cations, as well as likely a fourth one [Ni(HBPCINOL)](+). Potentiometric titration experiments confirm that under acid conditions, the dinuclear unit is broken. However, under neutral/basic pH values the dinuclear unit is stable and shows the presence of two water molecules coordinated to the nickel ions, resulting in the cation [Ni-2(HBPClNOL)(2)(H2O)(2)](2+). This cation shows two protonation/deprotonation equilibriums with pK(a) values of 9.68 and at 10.29, which are related to the aquo/hydroxo equilibrium associated with the water molecules coordinated to the metal ions. (c) 2006 Elsevier B.V. All rights reserved.|
dinuclear nickel (II) complex
|Editor:||Elsevier Science Bv|
|Appears in Collections:||Artigos e Materiais de Revistas Científicas - Unicamp|
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