[Pd(en)(H2O)2]2+ and [Pd(pic)(H2O)2]2+ complexation by monohydroxamic acids

A solution equilibrium and solid state approach

P. Buglyó, Krisztina Lénárt, Máté Kozsup, A. Bényei, Éva Kováts, I. Sóvágó, E. Farkas

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Complex formation between [Pd(en/pic)(H2O)2]2+ (en = ethylenediamine, pic = pyridine-2-methylamine) and primary hydroxamic acids (ahaH = acetohydroxamic, bhaH = benzohydroxamic acid) or secondary hydroxamic acids (meahaH = N-methyl-acetohydroxamic, pheahaH = N-phenylacetohydroxamic and phebhaH = N-phenylbenzohydroxamic acid) was studied in aqueous solution by pH-potentiometry, 1H NMR and ESI-TOF-MS. Secondary hydroxamates form 1:1 species with the [Pd(N,N)(H2O)2]2+ ions via the [O,O] chelating sets. Unexpectedly, in the primary ligands deprotonation and coordination of the hydroxamate-NH starts as low as pH CC(O)N-O- ion is capable of linking two [Pd(diamine)]2+ units via the coordination through the [O,O] chelate to one unit and through the monodentate hydroxymato-N- atom to the another one. As a consequence, primary ligands can bind an excess of metal ion too. A trinuclear complex predominates in a wide pH-range (5-10 for en, 3-10 for pic) and the hydroxide ion starts to compete with the hydroxymato ligand only above pH 10. In the trinuclear species two [O,O] chelated Pd(II) units are bridged via a third palladium core that binds to the hydroximato-N donors of the two ligands. This binding mode was also proved by MS studies in solution and by revealing the molecular structure of [(Pd(en))3(bhaH-1)2](BF4)2·2H2O (2), the first reported structure with a Pd(II)-hydroxymate-N- monodentate coordination, characterized with single crystal X-ray diffraction in the solid state.

Original languageEnglish
Pages (from-to)392-399
Number of pages8
JournalPolyhedron
Volume100
DOIs
Publication statusPublished - Nov 4 2015

Fingerprint

Complexation
Ligands
Hydroxamic Acids
solid state
ligands
acids
ethylenediamine
Acids
Ions
potentiometric analysis
Deprotonation
ions
Diamines
Palladium
diamines
Chelation
chelates
Pyridine
Molecular structure
hydroxides

Keywords

  • Hydroxamic acids
  • Hydroxymato-N coordination
  • Palladium
  • Speciation
  • Stability constants

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Materials Chemistry
  • Physical and Theoretical Chemistry

Cite this

[Pd(en)(H2O)2]2+ and [Pd(pic)(H2O)2]2+ complexation by monohydroxamic acids : A solution equilibrium and solid state approach. / Buglyó, P.; Lénárt, Krisztina; Kozsup, Máté; Bényei, A.; Kováts, Éva; Sóvágó, I.; Farkas, E.

In: Polyhedron, Vol. 100, 04.11.2015, p. 392-399.

Research output: Contribution to journalArticle

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abstract = "Complex formation between [Pd(en/pic)(H2O)2]2+ (en = ethylenediamine, pic = pyridine-2-methylamine) and primary hydroxamic acids (ahaH = acetohydroxamic, bhaH = benzohydroxamic acid) or secondary hydroxamic acids (meahaH = N-methyl-acetohydroxamic, pheahaH = N-phenylacetohydroxamic and phebhaH = N-phenylbenzohydroxamic acid) was studied in aqueous solution by pH-potentiometry, 1H NMR and ESI-TOF-MS. Secondary hydroxamates form 1:1 species with the [Pd(N,N)(H2O)2]2+ ions via the [O,O] chelating sets. Unexpectedly, in the primary ligands deprotonation and coordination of the hydroxamate-NH starts as low as pH CC(O)N-O- ion is capable of linking two [Pd(diamine)]2+ units via the coordination through the [O,O] chelate to one unit and through the monodentate hydroxymato-N- atom to the another one. As a consequence, primary ligands can bind an excess of metal ion too. A trinuclear complex predominates in a wide pH-range (5-10 for en, 3-10 for pic) and the hydroxide ion starts to compete with the hydroxymato ligand only above pH 10. In the trinuclear species two [O,O] chelated Pd(II) units are bridged via a third palladium core that binds to the hydroximato-N donors of the two ligands. This binding mode was also proved by MS studies in solution and by revealing the molecular structure of [(Pd(en))3(bhaH-1)2](BF4)2·2H2O (2), the first reported structure with a Pd(II)-hydroxymate-N- monodentate coordination, characterized with single crystal X-ray diffraction in the solid state.",
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AU - Buglyó, P.

AU - Lénárt, Krisztina

AU - Kozsup, Máté

AU - Bényei, A.

AU - Kováts, Éva

AU - Sóvágó, I.

AU - Farkas, E.

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N2 - Complex formation between [Pd(en/pic)(H2O)2]2+ (en = ethylenediamine, pic = pyridine-2-methylamine) and primary hydroxamic acids (ahaH = acetohydroxamic, bhaH = benzohydroxamic acid) or secondary hydroxamic acids (meahaH = N-methyl-acetohydroxamic, pheahaH = N-phenylacetohydroxamic and phebhaH = N-phenylbenzohydroxamic acid) was studied in aqueous solution by pH-potentiometry, 1H NMR and ESI-TOF-MS. Secondary hydroxamates form 1:1 species with the [Pd(N,N)(H2O)2]2+ ions via the [O,O] chelating sets. Unexpectedly, in the primary ligands deprotonation and coordination of the hydroxamate-NH starts as low as pH CC(O)N-O- ion is capable of linking two [Pd(diamine)]2+ units via the coordination through the [O,O] chelate to one unit and through the monodentate hydroxymato-N- atom to the another one. As a consequence, primary ligands can bind an excess of metal ion too. A trinuclear complex predominates in a wide pH-range (5-10 for en, 3-10 for pic) and the hydroxide ion starts to compete with the hydroxymato ligand only above pH 10. In the trinuclear species two [O,O] chelated Pd(II) units are bridged via a third palladium core that binds to the hydroximato-N donors of the two ligands. This binding mode was also proved by MS studies in solution and by revealing the molecular structure of [(Pd(en))3(bhaH-1)2](BF4)2·2H2O (2), the first reported structure with a Pd(II)-hydroxymate-N- monodentate coordination, characterized with single crystal X-ray diffraction in the solid state.

AB - Complex formation between [Pd(en/pic)(H2O)2]2+ (en = ethylenediamine, pic = pyridine-2-methylamine) and primary hydroxamic acids (ahaH = acetohydroxamic, bhaH = benzohydroxamic acid) or secondary hydroxamic acids (meahaH = N-methyl-acetohydroxamic, pheahaH = N-phenylacetohydroxamic and phebhaH = N-phenylbenzohydroxamic acid) was studied in aqueous solution by pH-potentiometry, 1H NMR and ESI-TOF-MS. Secondary hydroxamates form 1:1 species with the [Pd(N,N)(H2O)2]2+ ions via the [O,O] chelating sets. Unexpectedly, in the primary ligands deprotonation and coordination of the hydroxamate-NH starts as low as pH CC(O)N-O- ion is capable of linking two [Pd(diamine)]2+ units via the coordination through the [O,O] chelate to one unit and through the monodentate hydroxymato-N- atom to the another one. As a consequence, primary ligands can bind an excess of metal ion too. A trinuclear complex predominates in a wide pH-range (5-10 for en, 3-10 for pic) and the hydroxide ion starts to compete with the hydroxymato ligand only above pH 10. In the trinuclear species two [O,O] chelated Pd(II) units are bridged via a third palladium core that binds to the hydroximato-N donors of the two ligands. This binding mode was also proved by MS studies in solution and by revealing the molecular structure of [(Pd(en))3(bhaH-1)2](BF4)2·2H2O (2), the first reported structure with a Pd(II)-hydroxymate-N- monodentate coordination, characterized with single crystal X-ray diffraction in the solid state.

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KW - Speciation

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