Persistence of C-H center dot center dot center dot pi(chelate ring) interactions in the crystal structures of Pd(S2COR)(2). The utility of Pd(S2COR)(2) as precursors for palladium sulphide materials

The crystallographic structures of 12 palladium xanthates, Pd(S2COR)(2) (R = alkyl) show a uniform adoption of square-planar PdS4 geometries. Supramolecular aggregation in 1 (R = Me), 2 (Et) and 3 (n-Pr) is based on secondary Pd center dot center dot center dot S interactions, which are "turned off" when the bulk of R increases. In 4 (i-Pr), C-H center dot center dot center dot S hydrogen bonding is present. In each of 2-4, C-H center dot center dot center dot pi(PdS2C) interactions are incorporated within the architecture, stabilised by Pd center dot center dot center dot S secondary- or C-H center dot center dot center dot S hydrogen-bonding. In 5-12 (R = n-Bu, i-Bu, n-Pent, i-Pent, neoPent, n-Hex, i-Hex, neoHex), varying numbers of stand-alone C-H center dot center dot center dot pi(PdS2C) interactions involving different hydrogen donors uniformly stabilise supramolecular chains in their crystal structures. In order to determine the relative importance of the various intermolecular interactions and packing effects, a computational study using dispersion-corrected density-functional theory was performed on 3 (R = n-Pr). The results showed that the most significant contributors to the stability of the crystal structure are Pd center dot center dot center dot S interactions followed closely by C-H center dot center dot center dot pi(PdS2C) interactions. Two non-specific hydrophobic interactions also contribute to the overall packing to a lesser extent. The utility of Pd(S2COR)(2) to function as synthetic precursors for PdS nanoparticles and thin films was also investigated. Aerosol-assisted-CVD on representative examples generated PdS films with either matted, needle-like or granular morphologies depending on temperature and substrate. Solvothermal (ethylene glycol) decomposition generated sulphur-rich PdS nanoparticles with diameters 120 nm (7 and 10)-400 nm (8). When dodecanethiol was employed as a capping agent, PdS1.75 nanoparticles <10 nm were generated from 1.