Studies of the electronic properties of the tetrathiotungstate(VI) ion, [WS4]2–, by low-temperature absorption and resonance Raman spectroscopy

Abstract

The resonance Raman spectrum of the [WS₄]^2– ion as its [NH₄]⁺ and [NBu₄]⁺ salts has been studied over the range 647.1–350.7 nm. On the basis of the observed ν₁(a₁) band progressions, values for the harmonic wavenumber (ω₁) and anharmonicity constant (x₁₁) are calculated and the bandwidths are discussed in terms of contemporary theories. Computer simulation of the observed excitation profiles of the ν₁, 2ν₁, and 3ν₁, bands in the case of the [NBu₄]⁺ salt allows the deduction that, on excitation from the ground (¹A₁) to resonant excited (¹T₂) states, the W–S bond length increases by 0.058 Å.