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

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Abstract
Homoleptic d8‐metal organothiolates and phenylselenolates [M(EC6H5)2]∞ (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 X‐ray 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 , 3 , 4 , 5 ) conformations. The [M(SR)2]∞ 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 6 , 7 , 8 , 9 , 10 , 11 have the same [M(SR)2]∞ formulation as 1 and 2 . The cyclic complex [Pd6(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]∞ 13 and [Pd(SC16H33)2]∞ 14 ; these polymeric chains self‐assemble to give layer‐like 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 7×10−2 cm2 V−1 s−1 and 6×10−2 cm2 V−1 s−1, respectively.

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