Tungsten oxide as a universal source for the synthesis of complexes with different nuclearities in WO/chalcogen/NaCN systems.

Tungsten trioxide can be used as a readily available source in the one-step preparation of a variety of cyanide and chalcocyanide mononuclear and cluster complexes of tungsten. In our study of phase formation in the system 6WO + 8Q + 32NaCN (Q = S, Se or Te) in the temperature range of 250-700 °C, we determined which soluble complex compounds are formed, the temperature limits of their existence and the influence of synthesis time on the composition of the products. As the temperature increases, the process begins with the formation of mononuclear and then cluster complexes and ends with the formation of tungsten dichalcogenides: [W(CN)] → [WS]/[WSO] → [{WQ}(CN)] (Q = S or Se), [{WSO}(CN)] → [{WQ}(CN)] (Q = S, Se or Te) → WQ (Q = S or Se). Depending on the synthesis conditions, these complexes can either coexist in a mixture or one of them becomes the main product of the reaction. The obtained trinuclear and tetranuclear cluster complexes were studied by C, Se and W NMR spectroscopy using DFT calculations to assign the spectral signals. The crystal structures of the salts CsNa[W(CN)]·2HO (1), CsNa[{WS}(CN)]·2.2HO (2), Cs[{WSO}(CN)]·2HO·0.5CsCl (3) and CsNa[{WSe}(CN)]·6.5HO (4) were determined by single-crystal X-ray diffraction analysis. It was also revealed that the quantitative ratio of trinuclear complexes [{WSO}(CN)] and [{WS}(CN)] with different cluster core compositions formed in the 6WO + 8S + 32NaCN system at 300 °C depends on the synthesis time. Dynamics of the observed transformation of the initially dominant complex with a heteroleptic cluster core {W(μ-S)(μ-S)μ-O} into the complex with a homoleptic core {W(μ-S)(μ-S)} was studied using C NMR spectroscopy.