Polynuclear complexes with bridging pyrophosphate ligands: Synthesis and characterisation of {[(bipy)Cu(H2O)

Robert P. Doyle, Mark Nieuwenhuyzen, Paul E. Kruger

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

The reaction in water of M(II) ions (M = Cu, 1; Zn, 2; VO, 3) with 2,2′-bipyridine (bipy) followed by Na4P2O 7 leads to the formation of three new complexes which feature the pyrophosphate anion, P2O74-, as a bridging ligand. Single crystal X-ray diffraction revealed 1 to be {[(bipy)Cu(H 2O)(μ-P2O7)Na2(H 2O)6]·4H2O}, and 2 as a tetranuclear Zn(II) complex, {[(bipy)Zn(H2O)(μ-P2O 7)Zn(bipy)]2·14H2O}. The structure of 1 consists of a mononuclear [(bipy)Cu(H2O)(P2O 7)]2- unit that links via a pyrophosphate bridge to two Na atoms. The hydrated six-coordinate Na atoms themselves join together through bridging water molecules to generate a 2D Na-water sheet. The structure of 2 consists of a tetranuclear Zn(II) cluster (dimer-of-dimers) with two pyrophosphate ligands bridging between four metal centres. Adjacent clusters interact through face-to-face π-π interactions via the bipy ligands to yield a 2D sheet. Adjacent sheets pack in register to create channels, which are filled by the water molecules of crystallisation. An intricate 2D H-bonded water network separates adjacent sheets and encapsulates the tetranuclear clusters. Aspects of the pyrophosphate coordination modes in 1 and 2 are of structural relevance to those found within the inorganic pyrophosphatases. Compound 3, {[(bipy)(VO)2]2(μ-P2O 7)]·5H2O}, was isolated as an insoluble lime-green powder. Its dinuclear structure was elucidated from elemental and thermal analysis, magnetic susceptibility measurement and IR spectroscopy. The latter displayed characteristic bridging pyrophosphate and signature V=O stretches, which were corroborated by contrast to the IR spectra of 1 and 2 and through comparison with those found in the structurally characterised dinuclear complex, {[(bipy)Cu(H2O)]2(μ-P2O 7)·7H2O}, 4.

Original languageEnglish (US)
Pages (from-to)3745-3750
Number of pages6
JournalDalton Transactions
Issue number23
DOIs
StatePublished - Dec 7 2005

ASJC Scopus subject areas

  • Inorganic Chemistry

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