In situ complexation of thiourea in the interlayer space of copper(II)-montmorillonite

Intercalation of thiourea into the interlayer space of Cu(II)-montmorillonite was performed by solid–solid reaction at room temperature. The successful intercalation was proved by powder X-ray diffraction data and spectroscopic results. The basal spacing of the intercalation compound at the molar ratio 1:6 for copper(II) ion to thiourea was ca. 1.7 nm and the value was larger than that of the starting host material. The absence of the electron spin resonance signal of the product indicated that the copper(II) interlayer cation was reduced to copper(I) cation which remained in the interlayer space as a copper(I) thiourea complex. Both elemental (CHN) and thermogravimetry analyses, as well as Raman and infrared spectroscopy of the intercalation compound supported the presence of the copper(I) thiourea complex in the interlayer space montmorillonite.

Research Highlights
► Intercalation of thiourea was successfully investigated by solid-solid reactions.
► Thiourea reduced Cu(II) to Cu(I) remained in interlayer space as copper(I) thiourea.
► Raman band at 221 cm–1 indicated that 4-coordinate copper formed as a major product.