Letter | Published:

Raman Spectra of a Series of Square Planar Anions

Naturevolume 212page179 (1966) | Download Citation



OVER the past 10 years a number of reports have appeared in the literature on the infra-red spectra of square planar co-ordination compounds. Interest has been demonstrated in the exact whereabouts, in terms of frequency, of absorption bands associated primarily with stretching vibrations of metal–halogen bonds. A number of attempts have been made to estimate force constants for the metal ligand bonds in simple cases. A careful consideration of species with formula [MX4]n− and trans [MX2Y2], where M is a metal such as platinum(II), palladium(II) or gold (III), X is a halogen and Y is a donor system such as ammonia, a thio-ether or a phosphine, can provide a large amount of information particularly if the symmetric stretching modes of vibration are identified. Unfortunately, these modes are inactive in infra-red spectroscopy, and although they can be analysed by Raman spectroscopy, it is extremely difficult to obtain scattering data on deeply coloured materials such as these. The only reliable Raman spectra of compounds of this type is that due to Stammreich and Forneris1, who report three lines for each of the three anions, PtCl4− −, AuCl4− and AuBr4− using aqueous solutions and exciting the spectra with yellow, red or near-infra-red sources, as appropriate. An attempt which I made to obtain a spectrum from a solution of potassium tetrabromoplatinite by exciting the spectrum with an electrodeless rubidium arc was unsatisfactory; two indistinct features were observed near Δv = 190 and 120 cm−1.

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  1. 1

    Stammreich, H., and Forneris, R., Spectrochim. Acta, 16, 363 (1960).

  2. 2

    Nakamoto, K., Infra-red Spectra of Inorganic and Coordination Compounds, 113 (Wiley, New York, 1963).

  3. 3

    Hendra, P. J., and Sadasivan, N., Spectrochim. Acta, 21, 1271 (1965).

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  1. Department of Chemistry, University of Southampton

    • P. J. HENDRA


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