Covalently cyclopalladium(II) complex/reduced-graphene oxide as the effective catalyst for the Suzuki–Miyaura reaction at room temperature

Abstract

In this study, cyclometallated palladium complexes, [Pd(C^N)Cl(L)], in which C^N = N(1), C(2′)-chelated deprotonated 2-phenylpyridine, ppy, and L = dmso (dimethylsulfoxide) (complex 1) or PPh 3 (complex 2), have been synthesized. Also, complex 1 attached to amine functionalized graphene oxide (1-f-GO) has been synthesized by covalently bonding of complex 1 onto the graphene oxide surface through coordination interaction with 3-(aminomethyl)pyridine ligand spacers. The supported catalyst showed enhanced catalytic performance towards Suzuki-Miyaura reaction of aryl halides and phenylboronic acid at room temperature compared with the homogeneous analogues, and they could be readily recycled and reused several times without discernible loss of their activity.

Synergetic catalytic effect of rGO, Pd, Fe3O4 and PPy as a magnetically separable and recyclable nanocomposite for coupling reactions in green media

“…We compared our gained results of Suzuki reaction with reported results, taking the reactions of Aryl halide and phenylboronic acid for Suzuki coupling (Table ) . These factors make our nanocomposite as nanocatalyst superior to the others: absence of base as co‐catalyst, low reaction times with high yield in mild reaction conditions and easy work‐up method.…”

Graphene Oxide-Supported Oxime Palladacycles as Efficient Catalysts for the Suzuki–Miyaura Cross-Coupling Reaction of Aryl Bromides at Room Temperature under Aqueous Conditions

“…Catalysts 2017, 7, 94 2 of 16 of palladacycles to graphene materials, with two studies having been reported so far using covalent immobilization strategies [62,63]. Very recently, we have shown that palladium nanoparticles (Pd NPs), supported on graphene and reduced graphene oxide, efficiently catalyze the Suzuki-Miyaura coupling between aryl bromides and potassium aryltrifluoroborates under aqueous and low loading conditions (0.1 mol % Pd) employing conventional or microwave heating [64].…”

“…Thus, performing the palladation reaction using THF as solvent before immobilization onto GO led to the integral cyclopalladated species being supported. In fact, Pd(0) has been previously detected when anchoring oxime palladacycles to different supports such as, 3-hydroxypropyltriethoxysilylfunctionalized MCM-41 [17] and 3-(aminomethyl)pyridine-functionalized graphene oxide [63]. Figures 2 and 3 show the XPS spectra of 1 and 1-GO where the spectroscopic signature of palladium, carbon, oxygen, and nitrogen atoms has been determined [71][72][73] Regarding palladium (Figure 3a), the Pd3d XPS spectrum for 1 and 1-GO showed the corresponding binding energies at 337.70 (3d5/2) and 343.02 (3d3/2) eV and 337.62 (3d5/2) and 342.83 (3d3/2) eV, respectively.…”

“…These energies were assigned to the Cl-Pd bonding energy from the oxime palladacycle 1. The band at 200.1 8 eV corresponded to the 2p3/2 aromatic-Cl bonding energy (Figure 3e) [63]. Thermogravimetric analysis (TGA) of 1 (line blue), GO (black), and 1-GO (line red) was next performed ( Figure 4).…”

“…This type of catalyst has been mainly used in the Suzuki-Miyaura cross-coupling reaction [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62]. However, to the best of our knowledge, only very recently has some attention been paid to the immobilization of palladacycles to graphene materials, with two studies having been reported so far using covalent immobilization strategies [63,64].…”