Synthesis, structural, magnetic and thermal characterization of {[Cu(bipy)]2(μ-HP2O7)(μ-Cl)} ·H2O

Oluwatayo F. Ikotun, Elizabeth M. Higbee, Wayne Ouellette, Francesc Lloret, Miguel Julve, Robert Patrick Doyle

Research output: Contribution to journalArticle

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Abstract

Copper(II) hydroxide reacts with 2,2′-bipyridine (bipy) and sodium pyrophosphate in a 2:2:1 stoichiometric ratio under ambient conditions at pH 1.6 in water. The resulting neutral dinuclear CuII complex features a bridging set containing bridging monoprotonated pyrophosphate and a monoatomic chloro bridge (making this the first pyrophosphate bridged coordination complex containing an alternate, additional halide bridge between the metal centers). Single-crystal X-ray diffraction studies revealed the complex to be {[Cu(bipy)]2(μ-HP2O7)(μ-Cl)} ·H2O. The structure consists of a dimeric copper(II) system with each metal ion in a square pyramidal geometry. The asymmetric [Cu(bipy)]2+ units are bridged by bis-bidentate pyrophosphate and an axially bridging chlorine atom. The incorporation of an additional bridge (halide) and the presence of protonated pyrophosphate (HP2O 73-) in the structure are both rare for this family of structures. Inter-molecular π-π interactions between the bipy ligands from adjacent dinuclear complexes and hydrogen bonding between the lattice water molecule and the bridging chloro atom create a 1D network. Variable-temperature magnetic susceptibility measurements show the occurrence of a weak antiferromagnetic interaction with a maximum at 3.0 K. The analysis of the magnetic data in the whole temperature range (1.9-300 K) allows the determination of the value of the intramolecular magnetic coupling (J = -3.19 cm-1, the Hamiltonian being defined as Ĥ = - JŜAB). This value of J is significantly lower than that observed for the analogous dicopper(II) system devoid of the bridging chloro group. Reasons for this difference and its importance are discussed.

Original languageEnglish (US)
Pages (from-to)5281-5286
Number of pages6
JournalEuropean Journal of Inorganic Chemistry
Issue number33
DOIs
StatePublished - Nov 2008

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Keywords

  • Copper complexes
  • Magnetic coupling
  • Polynuclear compounds
  • Pyrophosphate

ASJC Scopus subject areas

  • Inorganic Chemistry

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