NHC Pd(II) and Ag(I) Complexes: Synthesis, Structure, and Catalytic Activity in Three Types of C–C Coupling Reactions

Abstract

Four bis-benzimidazolium salts, 1,4-bis[1′-( N -R-benzimidazoliumyl)methyl]-2,3,5,6-tetramethylbenzene 2X – ( L 1 H 2 ·(PF 6 ) 2 : R = ethyl, X = PF 6 ; L 2 H 2 ·Br 2 : R = picolyl, X = Br; L 3 H 2 ·Br 2 : R = benzyl, X = Br; and L 4 H 2 ·Br 2 : R = allyl, X = Br), and their three N -heterocyclic carbene (NHC) Pd(II) and Ag(I) complexes, L 1 Pd 2 Cl 4 ( 1 ), L 2 Ag 2 Br 2 ( 2 ), and L 4 (AgBr) 2 ( 3 ), as well as one anionic complex L 3 H 2 ·(Ag 4 Br 8 ) 0.5 ( 4 ), have been synthesized and characterized. Complex 1 adopts a funnel-like type of structure, complex 2 adopts a cyclic structure, and complex 3 is an open structure. In the crystal packing of 1 – 4 , one-dimensional polymeric chains and two-dimensional supramolecular layers are formed via intermolecular weak interactions, including hydrogen bonds, π–π interactions, and C–H···π contacts. The catalytic activities of NHC Pd(II) complex 1 in three types of C–C coupling reactions (Suzuki–Miyaura, Heck–Mizoroki, and Sonogashira reactions) were studied. The results show that this catalytic system is efficient for these C–C coupling reactions.

Is the Way to Fight Cancer Paved with Gold? Metal-Based Carbene Complexes with Multiple and Fascinating Biological Features

“…The signal for the carbene carbon in NHC Ag(I) complex AgL5 is invisible. This phenomenon has been reported also for some other Ag(I) carbene complexes, which may result from the fluxional behavior of NHC Ag(I) complexes [18][19][20][21]. ESI-MS spectrum gives a multiplicity of signals between 483.0 and 485.8 Dalton attributable to [C 18 H 18 AgBrN 2 O 2 + H + ] + , due to two silver (107 and 109) and two bromine (79 and 81) isotopes with a very similar relative abundance.…”

Polymer‐supported palladium (II) containing N2O2: An efficient and robust heterogeneous catalyst for C–C coupling reactions

“…Thus TbPo‐Pd(II) was attempted as catalyst in the Suzuki–Miyaura coupling reaction, and amazing effect was observed. First, the previous studies reported that the influences of solvents and bases were significant for the Suzuki–Miyaura coupling reaction . So, the promotional effect between solvents and TbPo‐Pd(II) was initially investigated with bromobenzene as the typical substrate, during which K 3 PO 4 ·3H 2 O was applied as the base, and the results are summarized in Table (entries 1–10).…”

Chroman‐4‐one‐Based Amino Bidentate Ligand: An Efficient Ligand for Suzuki‐Miyaura and Mizoroki‐Heck Coupling Reactions in Aqueous Medium

“…(E)-1-styrylnaphthalene (10 b): [46] White solid; Yield: 95 %; 68-70°C; [45] Yellow solid; Yield: 92 %; m.p 112-114°C; 1 H NMR (500 MHz, CDCl 3 ) δ 10.02 (s, 1H), 7.90 (d, J = 7.7 Hz, 2H), 7.68 (d, J = 7.7 Hz, 2H), 7.57 (d, J = 7.4 Hz, 2H), 7.41 (t, J = 7.3 Hz, 2H), 7.34 (t, J = 7.2 Hz, 1H), 7.27 (s, 1H), 7.17 (d, J = 16.3 Hz, 1H). 13 (E)-1-(4-styrylphenyl)ethan-1-one (10 d): [45] Yellow solid; Yield: 93 %; m.p 138-141°C; 1 H NMR (400 MHz, CDCl 3 ) δ 7.94 (d, J = 8.3 Hz, 2H), 7.57 (d, J = 8.3 Hz, 2H), 7.53 (d, J = 7.5 Hz, 2H), 7.37 (t, J = 7.6 Hz, 2H), 7.29 (t, J = 7.3 Hz, 1H), 7.24-7.10 (m, 2H), 2.59 (s, 3H).…”