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Pyrazole‐Stabilized Dinuclear Palladium(II) Chalcogenolates Formed by Oxidative Addition of Bis[2‐(4‐bromopyrazol‐1‐yl)ethyl] Dichalcogenides to Palladium(II) – Tailoring of Pd–S/Se Nanoparticles
Author(s) -
Nayan Sharma Kamal,
Joshi Hemant,
Prakash Om,
Sharma Alpesh K.,
Bhaskar Renu,
Singh Ajai K.
Publication year - 2015
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201500529
Subject(s) - chemistry , palladium , oxidative addition , diselenide , medicinal chemistry , reductive elimination , pyrazole , thioether , infrared spectroscopy , stereochemistry , crystallography , selenium , catalysis , organic chemistry
Bis[2‐(4‐bromopyrazol‐1‐yl)ethyl] disulfide and diselenide L1 and L2 were synthesized by the reactions of 4‐bromo‐1‐(2‐chloroethyl)‐1 H ‐pyrazole with the in situ generated Na 2 S 2 and Na 2 Se 2 . The reactions of L1 and L2 with 2 equiv. of [PdCl 2 (CH 3 CN) 2 ] in CH 3 CN at 70 °C proceed through an oxidative addition/reductive elimination sequence to the Pd II center to form the chalcogenolato‐bridged dinuclear palladium(II) complexes [Pd 2 Cl 2 (μ‐EN) 2 ] [ 1 (E = S) and 2 (E = Se); EN = 2‐(4‐bromopyrazol‐1‐yl)ethanechalcogenolate]. The reactions of 1 and 2 with CH 3 CN and AgBF 4 resulted in the formation of [Pd 2 (CH 3 CN) 2 (μ‐EN) 2 ] · 2BF 4 ( 3 and 4 ). Compounds L1 , L2 , and their complexes 1 – 4 have been characterized through 1 H, 13 C{ 1 H}, and 77 Se{ 1 H} nuclear magnetic resonance (NMR) spectroscopy; infrared (IR) spectroscopy; and high‐resolution mass spectrometry (HRMS). The single‐crystal X‐ray structures of 2 – 4 have revealed distorted square‐planar geometries around the Pd center in each case. The Pd–S and Pd–Se bond lengths are in the ranges 2.277(2)–2.296(2) and 2.372(9)–2.3971(17) Å, respectively. Single‐source precursor routes for the synthesis of palladium chalcogenide nanoparticles (NPs) have been developed by the thermolyses of 1 – 4 in 1:1 mixtures of oleic acid (OA) and 1‐octadecene (ODE). Pd 17 Se 15 NPs were formed from both Pd II selenolates 2 and 4 , whereas Pd 4 S NPs and a mixture of Pd 16 S 7 (ca. 68 %) and PdS (ca. 32 %) NPs were obtained from Pd II thiolates 1 and 3 , respectively. Transmission electron microscopy (TEM), scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM‐EDX), and powder X‐ray diffraction (PXRD) have been used to authenticate the NPs. X‐ray photoelectron spectroscopy (XPS) studies on the NPs have revealed that there is a charge transfer from Pd to S/Se. The compositions of the NPs determined from XPS are consistent with the PXRD results.