The nature of species derived from [Pt(bipy)2]2+ in aqueous solution: X-ray structural, mass spectral, NMR, and computational studies

Germán Cavigliasso*, Robert Stranger, Warrick K.C. Lo, James D. Crowley, Allan G. Blackman

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    10 Citations (Scopus)

    Abstract

    The reaction of [Pt(bipy)2]2+ with a variety of organic and inorganic ligands in aqueous solution has been studied by 195Pt, 1H and 13C NMR, X-ray crystallography, UV-Vis spectroscopy and high-resolution mass spectrometry. 195Pt NMR spectra of D2O solutions containing equimolar amounts of [Pt(bipy)2]2+ and the heterocyclic N donor ligands pyridine, 3-methylpyridine and 4-methylpyridine give evidence for the formation of at least one species, while quinoline appears to give only a single product under the same conditions. These results are supported by 1H and 13C NMR data. The complex [Pt(bipy)(py)2](ClO 4)2 was isolated from a reaction mixture containing equimolar amounts of [Pt(bipy)2]2+ and pyridine, and was characterised by X-ray crystallography. The 195Pt NMR chemical shift of this material suggested the presence of [Pt(bipy)(R-py)2] 2+ species in aqueous solutions containing equimolar amounts of [Pt(bipy)2]2+ and R-py (R-py = py, 3-Mepy, 4-Mepy). High-resolution mass spectral analysis of aqueous solutions containing [Pt(bipy)2]2+ and inorganic ligands L (L = OH-, S2O32-, N3-, SCN-, CN-, Cl- and SO42-) gives strong evidence for the formation of pseudo five-coordinate complexes of the type [Pt(bipy-κ2N,N′)(bipy-κN)(L)] n+ in the cases of OH-, S2O32-, N3- and SCN-. The results of calculations aimed at determining the 195Pt NMR chemical shifts of the possible species resulting from the reaction of [Pt(bipy)2]2+ with OH- in aqueous solution are consistent with the formation of pseudo five-coordinate [Pt(bipy-κ2N,N′)(bipy-κN)(OH)]+, but are not absolutely conclusive. However, the bonding energy of this complex is calculated to be significantly lower than that of any species resulting from OH- attack at a bipy ligand of [Pt(bipy)2]2+.

    Original languageEnglish
    Pages (from-to)238-246
    Number of pages9
    JournalPolyhedron
    Volume64
    DOIs
    Publication statusPublished - 2013

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