Alkali metal complexes thiourea

Stewart studied solid-phase reactions between thiourea and some alkali halides. He noted very little reaction in sodium chloride or bromide or in potassium chloride and tentatively suggested a coordination involving the alkali metal and sulfur to account for the changes in the spectrum as measured in potassium bromide or iodide or cesium bromide. He postulated that the more tightly bound alkali halides were not ruptured in pressing, although the complexes involving these ions could be prepared in solutions. 

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