STRUCTURE-SPECTROSCOPY CORRELATIONS IN SILVER THIOLATES - APPLICATIONTO THE STRUCTURE OF SILVER 1,5-PENTANEDITHIOLATE

A variety of spectroscopic methods have been used to deduce the solid- state structure of Ag-2[S(CH2)(5)S] (1), the yellow compound formed by mixing of Ag+ and 1,5-pentanedithiol. Solid-state reflectance UV-vis, X-ray diffraction, cross-polarization magic angle spinning (CPMAS) C- 13 NMR, and CPMAS Ag-109 NMR spectra of 1 were compared to correspondi ng spectra for two crystallographically-characterized homoleptic Ag th iolates, the cluster N(CH3)(2)}(3){mu(2)-S(CH2)(3)NH(CH3)(2)}(3)(ClO4) 2 (2) and the infinite strand AgSC(CH2CH3)(2)CH3 (3). Two limiting geo metries for 1 are considered: a linear polymer and a layered geometry similar to that adopted by neutral Ag thiolates with primary, unbranch ed alkane chains. All spectroscopic data are consistent with the latte r structure. Information about alkane chain orientation and Ag-S vibra tional modes in 1 was obtained by comparison of low-wavenumber Raman a nd diffuse reflectance infrared Fourier transform (DRIFT) spectra with those for all-trans AgS(CH2)(3)CH3 (T) and the C(1)-C(2) gauche isome r (G). The spectra show that the majority of alkane chains in 1 adopt a fully extended, all-trans geometry, but that gauche conformers are c learly present. These experiments demonstrate that sensitive structure elucidation can be achieved by combination of solid-state spectroscop ic methods, when appropriate standards are available. Although isostru ctural layered, neutral compounds of the form AgSR exhibit liquid crys talline behavior upon melting, 1 does not, a consequence of covalent a ttachment between layers.