Homoleptic Platinum(II) and Palladium(II) Organothiolates and Phenylselenolates: Solvothermal Synthesis, Structural Determination, Optical Properties, and Single-Source Precursors for PdSe and PdS Nanocrystals

Homoleptic d(8)-metal organothiolates and phenylselenolates [M-(EC6H5)(2)](infinity)( EC6H5)(2)](infinity) (E=S, M=Pt 1, M=Pd 2, M=Ni 5; E=Se, M=Pt 3, M=Pd 4) were prepared as crystalline solids under solvothermal conditions. Their structures were solved using powder Xray diffraction data. In each case, the EC6H5 (E=S, Se) ligand binds to two metal ions (M=Pt, Pd, and Ni) to form chain-like structures with planar (in 1) or zig-zag (in 2-5) conformations. The [M(SR) 2] 1 complexes (M=Pt, R=4-tert-butylphenyl 6; R=2-naphthyl 8; R=4-nitrophenyl 10 and M= Pd, R=4-tert- butylphenyl 7; R=2-naphthyl 9; R=4-nitrophenyl 11) were prepared under similar solvothermal conditions. Based on the XPS binding energies and elemental analyses, complexes 611 have the same [M(SR)(2)](infinity) formulation as 1 and 2. The cyclic complex [Pd-6 (SCH3)(12)] 12 was prepared as a crystalline solid by solvothermal annealing treatment of the amorphous precipitate. A chain-like polymer structure is proposed for both [Pd(SC12H25)(2)](infinity) 13 and [Pd(SC16H33)(2)](infinity) 14; these polymeric chains self- assemble to give layerlike structures. Solid-state diffuse reflectance spectra reveal that the optical band gap Eg (eV)of complexes 1, 6, 8, 10 and of 2, 7, 9, 11 are in the range of 2.10-3.00 eV and 2.10-2.63 eV, respectively, and 5 has the lowest Eg value (1.72 eV). Heating solid samples of 4 and 13 under solvothermal conditions afforded phase-pure Pd17Se15 and PdS nanocrystals, respectively. Field-effect transistors fabricated with a drop-cast thin film made from Pd17Se15 nanocrystals prior treated with an ethanolic solution of 1-hexadecanethiol displayed ambipolar charge transporting properties with hole and electron mobility being 7x10(-2) cm(2)V(-1) s(-1) and 6x10(-2) cm(2)V(-1)s(-1), respectively.