Synthesis of Fe and Cu metal complexes derived from ‘SNS’ Pincer type ligands and their efficient catalyst precursors for the chemical fixation of $$\hbox {CO}_{2}$$ CO 2

Abstract

Two novel tridentate SNS pincer type ligands, 2,6-bis[[(2-methoxyphenyl)thio]methyl]pyridine (L1) and 2,6-bis[[(2-chlorophenyl)thio]methyl]pyridine (L2), each possessing two sulfur and one nitrogen donor functionalities (SNS), based on 2,6-bis(thioether)pyridine ligands were prepared and metallised with CuCl 2 • 2H 2 O and FeCl 2 • 4H 2 O metal salts. Two new unanticipated complexes were obtained from the L2 ligand, the dimeric bidentate Cu(I) complex [Cu 2 (κ 2 −L2) 2 Cl 2 ] and tridentate Fe(II) complex [Fe(κ 3 −L2)Cl 2 ] while two new tridentate pincer-type complexes M(κ 3-L1)Cl 2 ] (M = Cu, Fe) were formed from the L1 ligand. It was observed that the structure of this Cu(I) complex has a tetrahedral geometry using single crystal Xray diffraction analysis. In addition, catalytic properties of metal complexes towards the formation of cyclic carbonates from CO 2 and epoxides were investigated. The less sterically hindered Fe(II) complex with the L1 ligand [Fe(κ 3 −L1)Cl 2 ] (2) showed the best catalytic activity. Several parameters including temperature, time, epoxide identity and CO 2 pressure were investigated to find the optimum catalytic reaction conditions. Moreover, DFT studies of these compounds are presented in the study.

Pd (II) complexes bearing “SNS” pincer‐type thioether ligands: Application as catalysts in the synthesis of vitamin K3

“…The L3‐Pd (II) complex was synthesized by the similar route given as compound L1‐Pd (II) using Pd (OAc) 2 (0.112 g, 0.5 mmol) and 2,6‐bis[[(2‐methoxyphenyl)thio]methyl]pyridine SNS‐3 [ 22 ] (0.192 g, 0.5 mmol). The obtained product was gradually purified with the vapor diffusion of Et 2 O to a THF solution of complex L3‐Pd (II) which was a reddish‐brown colored compound (Figure 1).…”

“…The obtained product was gradually purified with the vapor diffusion of Et 2 O to a THF solution of complex L3-Pd (II) which was a reddish-brown colored compound (Figure 1). Yield: 0.144 g (46% The L4-Pd (II) complex was synthesized by the similar route given as compound L1-Pd (II) using Pd (OAc) 2 (0.112 g, 1 mmol) and 2,6-bis[[(2-chlorophenyl)thio] methyl]pyridine SNS-4 [22] (0.196 g, 0.5 mmol). The obtained product was gradually purified with the vapor diffusion of Et 2 O to a THF solution of complex L4-Pd (II) which was a brown colored compound (Figure 1).…”