Temperature-dependent FT-IR spectroscopy study of silver 1,9-nonanedithiolate

Abstract

The structure and thermal behavior of silver 1,9-nonanedithiolate (AgNDT) is investigated by means of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and elemental analysis. The XRD data suggests that AgNDT has a layered structure but with poor registry between layers. The poor registry seems to be associated with the deficiency of Ag by 20% in binding to the available sulfur atoms. DRIFT spectral data nonetheless indicates that the carbon chains take nearly all-trans conformation. The temperature-dependent DRIFT spectral data suggests that AgNDT should degrade at >530 K without any thermodynamic phase transition, in agreement with the TGA and DSC analysis. The finding that AgNDT does not exhibit liquid-crystalline behavior upon melting is attributed to the formation of two Ag-S bonds (as alpha,omega -dithiolate) in AgNDT, even though each Ag atom is trigonally bonded to sulfur, as in silver monothiolate (AgSR).