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

Abstract

Homoleptic d(8)-metal organothiolates and phenylselenolates [M(EC(6)H(5))(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 X-ray diffraction data. In each case, the EC(6)H(5) (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)](infinity) 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 6-11 have the same [M(SR)(2)](infinity) formulation as 1 and 2. The cyclic complex [Pd(6)(SCH(3))(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(SC(12)H(25))(2)](infinity) 13 and [Pd(SC(16)H(33))(2)](infinity) 14; these polymeric chains self-assemble to give layer-like structures. Solid-state diffuse reflectance spectra reveal that the optical band gap E(g) (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 E(g) value (1.72 eV). Heating solid samples of 4 and 13 under solvothermal conditions afforded phase-pure Pd(17)Se(15) and PdS nanocrystals, respectively. Field-effect transistors fabricated with a drop-cast thin film made from Pd(17)Se(15) 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.

Tiara-like Octanuclear Palladium(II) and Platinum(II) Thiolates and Their Inclusion Complexes with Dihalo- or Iodoalkanes

“…Metal thiolates are an important class of compounds because of their structural diversity in coordination chemistry, − relevance to cofactors of metalloproteins in biological systems, , and importance in cluster and surface science , and catalysis . Thiolate-bridged polynuclear group 10 transition-metal complexes with chain structures that have the general formula of [M(μ-SR) 2 ] n (M = Ni, Pd) have been investigated in detail because they provide efficient catalysis of atom-economical organic reactions such as regioselective additions of thiols and disulfides across alkynes. − Tiara-like complexes, which are also polynuclear group 10 transition-metal thiolates and are characterized by toroidal architectures, have been studied extensively, both in terms of their intriguing structural features and with respect to the preparation of monodisperse metal sulfide nanoparticles, nonlinear optical materials, photoactive water-reducing catalysts, , and host–guest chemistry. ,− Tiara-like nickel complexes have received considerable attention, resulting in the preparation of complexes with a variety of ring sizes that have the general formula of [Ni(μ-SR) 2 ] n ( n = 4–6, 8–12). ,,,− In contrast, although several tiara-like hexanuclear palladium complexes have been reported, ,,,− only one octanuclear complex, namely, [Pd(μ-S n Pr) 2 ] 8 , is known and was obtained as a mixture with hexanuclear [Pd(μ-S n Pr) 2 ] 6 . For platinum, infinite thiolates and selenolates that have the general formula of [Pt(μ-ER) 2 ] ∞ (E = S, Se) have been synthesized using a solvothermal method; however, to the best of our knowledge, no tiara-like complexes have been reported thus far.…”

Oligomeric allyl-palladium(ii) complexes of β-substituted ethylselenolates: Syntheses, structures and thermal decomposition

“…Our group 4,5 and others 10-12 have used allyl palladium dichalcogenolates for the synthesis of palladium chalcogenides (Pd x E y ). The latter find applications in the semiconductor industry 13,14 and in catalytic reactions such as dehydrosulfurization, 15 dehydrogenation 16 and C-C couplings. 17 The allyl-palladium complexes with anionic monodentate chalcogenolate ligands exist as dimeric molecules, 4,5 which on thermolysis yield palladium rich chalcogenides, such as Pd 4 Se.…”

Tiara-like Hexanuclear Nickel–Platinum Alloy Nanocluster

“…Multinuclear metal complexes, termed metal nanoclusters (NCs), exhibit physicochemical properties different from those of bulk metals that are composed of the same metal elements. − In particular, tiara-like metal NCs (TNCs) are ring compounds containing metal ions and can be synthesized in air for the group 10 metals, such as nickel (Ni), − palladium (Pd), − and platinum (Pt). − They are widely used in a variety of fields, including catalysis, perhaps in part because of their relative ease of handling. − Alloying enables precise control of the electronic and geometric structure of NCs, thus facilitating further functionalization. Therefore, alloying with various metals has been reported in many cases, especially for thiolate (SR)-protected gold (Au) NCs [Au n (SR) m ] and silver (Ag) NCs [Ag n (SR) m ]. ,, For TNCs, those encapsulating various metals and molecules can also be synthesized. ,,,− For instance, in alloy TNCs with Ag­(I) encapsulation by Pt 6 (SR) 12 , AgPt 6 (SR) 12 (SR = 1-octanethiolate; SC 8 H 17 , 1-dodecanethiolate; SC 12 H 25 ) has been reported with a new optical transition orbit based on charge transfer between Ag and Pt, and the luminescence quantum yield is substantially enhanced by the encapsulation (Figure A) .…”

“…Multinuclear metal complexes, termed metal nanoclusters (NCs), exhibit physicochemical properties different from those of bulk metals that are composed of the same metal elements. 1 − 17 In particular, tiara-like metal NCs (TNCs) are ring compounds containing metal ions and can be synthesized in air for the group 10 metals, such as nickel (Ni), 18 − 24 palladium (Pd), 25 − 31 and platinum (Pt). 30 − 33 They are widely used in a variety of fields, including catalysis, perhaps in part because of their relative ease of handling.…”