Preparation,structure and spectroscopic studies of the palladium mercaptides Pd8(S-nPr)16 and Pd6(S-nPr)12

Various palladium salts react with n-propane thiol to form a mixture of the cyclic mercaptides Pd₈(S-nPr)₁₆ (I) and the known Pd₆(S-nPr)₁₂ (II). I is described as an octagonal toroid, containing a planar ring of palladium atoms, each being bridged by four mercapto groups in approximately square planar geometry. The pendant n-propyl groups radiate outward in approximately axial and equatorial orientations with respect to the ring, which was also observed in solution by ¹H and ¹³C NMR. Crystal data: space group C2/c, a=22.251(15), b=27.623(6), c=14.621(17) Å, β=116.35°(4), V=8053(4) ų. Least-squares refinement based on 3103 observed reflections led to an R value of 0.078. I and II failed to complex any appropriate guest species, as evidenced by the UV-Vis spectra. I was found to have a reversible oxidation wave at E/2= 0.77 V, and a irreversible oxidation wave of 1.09 V. II displayed two irreversible peak potentials at 0.77 and 1.09 V. In each case, the waves were one electron processes, in which the reversibility was not enhanced at low temperatures.