ESR and pH-potentiometric study of the mixed-ligand complex formation in the copper(II)-4-fluorosalicylic acid-N,N-diethylnicotinamide system: Structure and spectral properties of [Cu(4-fluorosalicylate)2(N,N- diethylnicotinamide)2(H2O)2] complex

Terézia Szabó-Plánka, Ján Moncol, Eszter Tóth, Béla Gyurcsik, Nóra Veronika Nagy, Zuzana Vasková, Antal Rockenbauer, Dušan Valigura

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Abstract

EPR simulation method together with pH-potentiometry combined with UV-Vis spectrophotometry were used for the study of the ternary system 4-fuorosalicylic acid (HA)-N,N-diethylnicotinamide (B)-copper(II) in aqueous solution. The N,N-diethylnicotinamide ligand is a weak donor, its mixed-ligand complexes with 4-fluorosalicylate anions are more favoured. The number of coordinated N,N-diethylnicotinamide molecules increases with decreasing temperature: up to four ones were detected in the coordination sphere of copper(II) in frozen solutions. The formation of [CuH-1AB2] and [CuH -1A] was detected by all methods at neutral pH. At lower pH values, [CuA2B2] and [CuB] become dominant, and this fact is in good agreement with [CuA2B2(H2O)2] crystals obtained from similar solutions. The structural unit of the [CuA 2B2(H2O)2] complex consists of a copper(II) ion, which is monodentately coordinated by a pair of 4-fluorosalicylate anions and by a pair of N,N-diethylnicotinamide in trans positions in the basal plane, and by two water molecules in the axial positions of a tetragonal bipyramid.

Original languageEnglish
Pages (from-to)2421-2429
Number of pages9
JournalPolyhedron
Volume30
Issue number14
DOIs
Publication statusPublished - Aug 30 2011

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Keywords

  • 4-Fluorosalicylic acid
  • Copper(II) complexes
  • Crystal structure
  • Electron spin resonance
  • N,N-Diethylnicotinamide
  • Speciation
  • pH-potentiometry

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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