| Popis: |
The complexes Pt(en)(SCN)2X, en = 1,2-diaminoethane, X = Br or I, have been synthesised and, on the basis of a study of their electronic, i.r., and resonance-Raman spectra, established to be linear-chain, halogen-bridged complexes, [Pt(en)(SCN)2][Pt(en)(SCN)2X2]. The electronic spectra are characterised by broad, intense bands (maxima at ca. 17 800 cm–1 for X = Br and at < 13 000 cm–1 for X = I). The i.r. spectra are near superpositions of those of the constituent complexes, the band shifts on complex formation being greater for the iodide-bridged complex. The resonance-Raman spectra are dominated by long overtone progressions in ν1, the Raman-active, symmetric (X–PtIV–X) stretch, reaching 7ν1 for X = Br or I. Subsidiary progressions v1ν1+νn are observed for X = Br, where νn is identified as ν(Pt–S)eq. The form of the resonance-Raman spectra, ν1 excitation profiles, and ν1 wavenumber dependence on the wavenumber of the exciting line, ν0, are discussed in terms of unresolved components of ν1 and of their relative intensity dependence on temperature and ν0. |
Plný text