Copper(i) 5-phenylpyrimidine-2-thiolate complexes showing unique optical properties and high visible light-directed catalytic performance

Abstract

Solvothermal reactions of 5-phenylpyrimidine-2-thiol (5-phpymtH) with equimolar CuBr afforded one hexanuclear cluster [Cu(μ-5-phpymt)] (1) along with a tetranuclear by-product [{(CuBr)(μ-5-phpymtH)}(μ-5-phpymt)] (2). A two dimensional (2D) polymer [Cu(μ-5-phpymt)(μ-Br)] (3) was isolated from the reaction of 5-phpymtH with two equiv. of CuBr. Analogous reactions of 5-phpymtH with one or four equiv. of CuI produced one tetranuclear cluster [{Cu(μ-5-phpymtH)(μ-5-phpymt)}(μ-I)] (4) and one 2D polymer [CuI(μ-I)(μ-5-phpymt)] (5). Compound 1 possesses a water-wheel-shaped hexameric structure. Compound 2 has an H-shaped tetrameric structure. Compound 3 possesses a 2D network in which unique 1D [Cu(μ-Br)(μ-5-phpymt)] chains are connected by μ-Br ions. Compound 4 has another tetrameric structure in which two {Cu(μ-5-phpymtH)(μ-5-phpymt)} fragments are linked by a pair of μ-I ions. Compound 5 contains another 2D network in which hexanuclear {CuI(μ-I)} units are linked by μ-5-phpymt bridges. The 5-phpymt ligand shows four coordination modes: μ-κ(S)-κ(N) (4), μ-κ(S)-κ(N) (1 and 2), μ-κ(N)-κ(S)-κ(N') (5) and μ-κ(N)-κ(S)-κ(N') (3). Complex 1 shows strong solvatochromic behaviour and displays reversible luminescence switching upon alternate addition of CFCOOH and EtN into its CHCl solution. Complexes 1-5 exhibit a high photocatalytic activity towards the aerobic oxidative hydroxylation of arylboronic acids to phenols under visible light irradiation. Catalyst 5 can be reused in several cycles without any obvious decay of the catalytic efficiency. These results offer an interesting insight into how the CuX/5-phpymtH molar ratios and X ions exert great impacts on the coordination modes of the 5-phpymt ligand, the structures of the final complexes, and the luminescence and catalytic properties.

Acceptorless Dehydrogenation of Alcohols Catalyzed by CuIN‐Heterocycle Thiolate Complexes

“…Second, N ‐heterocycle thiols such as pyridine‐2‐thione and pyrimidine‐2‐thione can coordinate at Cu I center in either neutral or anion state, which is beneficial in terms of metal–ligand bifunctional mechanism. Third, we and others have observed that Cu I complexes with N,S‐donor ligands exhibit high catalytic activity towards organic reactions such as C−C and C−N bond formations and photocatalytic activity towards the aerobic oxidative hydroxylation of arylboronic acids . Herein, we report an efficient approach for the acceptorless dehydrogenation of secondary/primary benzylic, allylic and aliphatic alcohols for the first time with Cu I N ‐heterocycle thiolate clusters.…”

Synthesis, Characterization, and Catalytic Activities of Palladium Complexes with Phenylene-Bridged Bis(thione) Ligands

“…Imidazoline-2-chalcogenone ligands NHCE (NHC = N-heterocyclic carbene, E = S, Se) and their transition-metal complexes play a crucial role in organometallic and coordination chemistry as well as in catalysis. − Imidazoline-2-chalcogenone ligands are good σ-donors and weak π-acceptors and can be easily modified using appropriate available NHC precursors to allow fine tuning of steric and electronic properties of the center metal complexes. A series of transition-metal complexes with imidazoline-2-chalcogenone ligands have been synthesized for various applications such as C–C bond formation, ,, borylation of alkynes, biomimetic activity, and hydrogen transfer reaction , in recent years. And the catalytic performance of these catalysts is comparable with those of the efficient metal–NHC complexes for organic transformation. , …”

New 19F NMR methodology reveals structures of molecules in complex mixtures of fluorinated compounds

“…Their structures were veried by a comparison of NMR parameters with literature data. 98,99 Performing such checks is generally recommended, especially in instances where the appearance of the identied compounds is difficult to rationalise. Such comparisons are considered to be reliable due to sensitivity of NMR parameters to molecular structures.…”