C–H bond chlorination and bromination using water soluble nickel( <scp>ii</scp> ) guanidine complexes

Water-soluble nickel(II)-guanidine-based complexes successfully catalyzed the C-H chlorination of a series of hydrocarbons in the presence of NaOCl and acetic acid in water-chloroform (7 : 3, biphasic condition) at room temperature. Majorly chlorinated products (TON ∼680 for cyclohexane) were obtained. Furthermore, C-H bond bromination of cyclohexane, <i>n</i>-hexane, and toluene was also carried out using <i>in situ</i> generation of NaOBr. These putative formations of Ni(III) species were characterized by electron paramagnetic resonance (EPR) spectroscopy, and the plausible mechanism for chlorination was confirmed by DFT calculations.