Cross coupling reactions of multiple C[sbnd]Cl bonds of polychlorinated solvents with Grignard reagent using a pincer nickel complex

Abstract

The nickel(II) complex of a bulky pincer-type ligand, N,N′-bis(2,6-diisopropylphenyl)-2,6-pyridinedicarboxamido, was examined for sp3–sp3 coupling of Grignard reagents with polychlorinated solvents. The nickel(II) complex catalyzed CC coupling of polychlorinated alkyl halides, such as dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4), with various Grignard reagents. The effective activation of multiple CCl bonds proceeded under ambient reaction conditions and within a short time (20min). This catalyst displays the highest activity yet reported for this reaction type, with catalyst loading as low as 0.4mol% and turnover frequency (TOF) as high as 724h−1. The catalyst is capable of replacing all chlorine atoms with CC bond formations for all of the polychlorinated solvents under investigation. The catalytic process could prove to be an efficient method of remediation of toxic polychlorinated solvents while generating synthetically and commercially important chemicals.