Synthesis and solution behaviour of stable mono-, di-and trinuclear Pd(II) complexes of 2,5-pyridinedihydroxamic acid: X-ray crystal structure of a novel Pd(II) hydroxamato complex

Darren M. Griffith, Linda Bíró, James A. Platts, Helge Müller-Bunz, E. Farkas, P. Buglyó

Research output: Contribution to journalArticle

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Abstract

Mono-, di-and trinuclear Pd(II) complexes of 2,5-pyridinedihydroxamic acid (2,5-pyha) are reported. The X-ray crystal structure of the mononuclear complex, [Pd(en)(2,5-pyha -1H)]Cl (en = ethylenediamine), was determined exhibiting an (N py,N) binding mode of 2,5-pyha where (N py,N) is through a pyridine N and deprotonated hydroxamate N. Such a coordination mode has never previously been observed for a Pd(II) hydroxamato complex. The first examples of di-and trinuclear Pd(II) complexes of a hydroxamic acid are described where one 2,5-pyha ligand acts as a bridge for two and three Pd(en) moieties, respectively. The stability of potential binding modes of 2,5-pyha for a proposed dinuclear complex were investigated by density functional theory at the RI-BP86/def2-TZVP level, in the Turbomole package. It was found that (N py,N), (O,O′) 2 gave the more stable complex where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) 2 is via the carbonyl oxygen atom and the deprotonated hydroxyl group of the hydroxamic acid at the 2-position on the pyridine ring. A trinuclear complex, [{Pd(en)} 3(2,5-pyha -4H)](PF 6) 2 was isolated and fully characterised. Spectroscopic studies indicate that the coordination modes are (N py,N), (O,O′) 2 and (O,O′) 5 where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) is via doubly deprotonated hydroximate groups at positions 2 and 5 on the pyridine ring. Stability constants for the mono-, di-and trinuclear [Pd(en)] 2+ complexes of 2,5-pyridinedihydroxamic acid are also reported. In solution at equimolar concentrations, 2,5-pyha effectively binds one equivalent of Pd(II) to give a mononuclear Pd(II) 2,5-pyha complex and under strongly acidic conditions. In addition formation of stable trinuclear Pd(II) 2,5-pyha complexes are favoured at an excess of Pd(II).

Original languageEnglish
Pages (from-to)291-300
Number of pages10
JournalInorganica Chimica Acta
Volume380
Issue number1
DOIs
Publication statusPublished - Jan 15 2012

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Crystal structure
X rays
acids
crystal structure
Acids
synthesis
x rays
Pyridine
pyridines
Hydroxamic Acids
ethylenediamine
Hydroxyl Radical
rings
Density functional theory
pyridine
oxygen atoms
Oxygen
Ligands
Atoms
density functional theory

Keywords

  • Density functional theory
  • Hydroxamic acid
  • Palladium complex
  • Scavenger
  • Solution equilibrium
  • Stability constant

ASJC Scopus subject areas

  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

Synthesis and solution behaviour of stable mono-, di-and trinuclear Pd(II) complexes of 2,5-pyridinedihydroxamic acid : X-ray crystal structure of a novel Pd(II) hydroxamato complex. / Griffith, Darren M.; Bíró, Linda; Platts, James A.; Müller-Bunz, Helge; Farkas, E.; Buglyó, P.

In: Inorganica Chimica Acta, Vol. 380, No. 1, 15.01.2012, p. 291-300.

Research output: Contribution to journalArticle

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abstract = "Mono-, di-and trinuclear Pd(II) complexes of 2,5-pyridinedihydroxamic acid (2,5-pyha) are reported. The X-ray crystal structure of the mononuclear complex, [Pd(en)(2,5-pyha -1H)]Cl (en = ethylenediamine), was determined exhibiting an (N py,N) binding mode of 2,5-pyha where (N py,N) is through a pyridine N and deprotonated hydroxamate N. Such a coordination mode has never previously been observed for a Pd(II) hydroxamato complex. The first examples of di-and trinuclear Pd(II) complexes of a hydroxamic acid are described where one 2,5-pyha ligand acts as a bridge for two and three Pd(en) moieties, respectively. The stability of potential binding modes of 2,5-pyha for a proposed dinuclear complex were investigated by density functional theory at the RI-BP86/def2-TZVP level, in the Turbomole package. It was found that (N py,N), (O,O′) 2 gave the more stable complex where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) 2 is via the carbonyl oxygen atom and the deprotonated hydroxyl group of the hydroxamic acid at the 2-position on the pyridine ring. A trinuclear complex, [{Pd(en)} 3(2,5-pyha -4H)](PF 6) 2 was isolated and fully characterised. Spectroscopic studies indicate that the coordination modes are (N py,N), (O,O′) 2 and (O,O′) 5 where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) is via doubly deprotonated hydroximate groups at positions 2 and 5 on the pyridine ring. Stability constants for the mono-, di-and trinuclear [Pd(en)] 2+ complexes of 2,5-pyridinedihydroxamic acid are also reported. In solution at equimolar concentrations, 2,5-pyha effectively binds one equivalent of Pd(II) to give a mononuclear Pd(II) 2,5-pyha complex and under strongly acidic conditions. In addition formation of stable trinuclear Pd(II) 2,5-pyha complexes are favoured at an excess of Pd(II).",
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AU - Griffith, Darren M.

AU - Bíró, Linda

AU - Platts, James A.

AU - Müller-Bunz, Helge

AU - Farkas, E.

AU - Buglyó, P.

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N2 - Mono-, di-and trinuclear Pd(II) complexes of 2,5-pyridinedihydroxamic acid (2,5-pyha) are reported. The X-ray crystal structure of the mononuclear complex, [Pd(en)(2,5-pyha -1H)]Cl (en = ethylenediamine), was determined exhibiting an (N py,N) binding mode of 2,5-pyha where (N py,N) is through a pyridine N and deprotonated hydroxamate N. Such a coordination mode has never previously been observed for a Pd(II) hydroxamato complex. The first examples of di-and trinuclear Pd(II) complexes of a hydroxamic acid are described where one 2,5-pyha ligand acts as a bridge for two and three Pd(en) moieties, respectively. The stability of potential binding modes of 2,5-pyha for a proposed dinuclear complex were investigated by density functional theory at the RI-BP86/def2-TZVP level, in the Turbomole package. It was found that (N py,N), (O,O′) 2 gave the more stable complex where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) 2 is via the carbonyl oxygen atom and the deprotonated hydroxyl group of the hydroxamic acid at the 2-position on the pyridine ring. A trinuclear complex, [{Pd(en)} 3(2,5-pyha -4H)](PF 6) 2 was isolated and fully characterised. Spectroscopic studies indicate that the coordination modes are (N py,N), (O,O′) 2 and (O,O′) 5 where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) is via doubly deprotonated hydroximate groups at positions 2 and 5 on the pyridine ring. Stability constants for the mono-, di-and trinuclear [Pd(en)] 2+ complexes of 2,5-pyridinedihydroxamic acid are also reported. In solution at equimolar concentrations, 2,5-pyha effectively binds one equivalent of Pd(II) to give a mononuclear Pd(II) 2,5-pyha complex and under strongly acidic conditions. In addition formation of stable trinuclear Pd(II) 2,5-pyha complexes are favoured at an excess of Pd(II).

AB - Mono-, di-and trinuclear Pd(II) complexes of 2,5-pyridinedihydroxamic acid (2,5-pyha) are reported. The X-ray crystal structure of the mononuclear complex, [Pd(en)(2,5-pyha -1H)]Cl (en = ethylenediamine), was determined exhibiting an (N py,N) binding mode of 2,5-pyha where (N py,N) is through a pyridine N and deprotonated hydroxamate N. Such a coordination mode has never previously been observed for a Pd(II) hydroxamato complex. The first examples of di-and trinuclear Pd(II) complexes of a hydroxamic acid are described where one 2,5-pyha ligand acts as a bridge for two and three Pd(en) moieties, respectively. The stability of potential binding modes of 2,5-pyha for a proposed dinuclear complex were investigated by density functional theory at the RI-BP86/def2-TZVP level, in the Turbomole package. It was found that (N py,N), (O,O′) 2 gave the more stable complex where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) 2 is via the carbonyl oxygen atom and the deprotonated hydroxyl group of the hydroxamic acid at the 2-position on the pyridine ring. A trinuclear complex, [{Pd(en)} 3(2,5-pyha -4H)](PF 6) 2 was isolated and fully characterised. Spectroscopic studies indicate that the coordination modes are (N py,N), (O,O′) 2 and (O,O′) 5 where (N py,N′) is through a pyridine N and deprotonated hydroximate N and (O,O′) is via doubly deprotonated hydroximate groups at positions 2 and 5 on the pyridine ring. Stability constants for the mono-, di-and trinuclear [Pd(en)] 2+ complexes of 2,5-pyridinedihydroxamic acid are also reported. In solution at equimolar concentrations, 2,5-pyha effectively binds one equivalent of Pd(II) to give a mononuclear Pd(II) 2,5-pyha complex and under strongly acidic conditions. In addition formation of stable trinuclear Pd(II) 2,5-pyha complexes are favoured at an excess of Pd(II).

KW - Density functional theory

KW - Hydroxamic acid

KW - Palladium complex

KW - Scavenger

KW - Solution equilibrium

KW - Stability constant

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