Facile activation of the C–I bond of primary alkyl halides by Pt(II) complexes having a benzothiazole ligand.

Kinetic and mechanism of addition of alkyl halides (RI = MeI and EtI) to [PtMe 2 (pbt)], in which pbt = 2-(2-pyridyl)benzothiazole, to give the Pt(IV) complexes [PtIRMe 2 (pbt)] were investigated. • The organoplatinum(II) and (IV) complexes of 2-(2-pyridyl)benzothiazole are synthesized. • New platinum complexes are characterized by NMR spectroscopy and X-ray crystallography. • The kinetics of oxidation of Pt(II) complex to Pt(IV) complex by alkyl halides are studied. The alkyl halides, RI (MeI and EtI), were oxidatively added to a Pt(II) complex [PtMe 2 (pbt)], 1 , in which pbt = 2-(2-pyridyl)benzothiazole, to give the Pt(IV) complexes [PtIRMe 2 (pbt)] (R = Me; 2 and R = Et; 3). Kinetics of the reactions in toluene and acetone were studied using UV–vis spectroscopy between 5 and 40 °C and an S N 2 mechanism was suggested. The reaction of MeI with complex 1 was considerably faster than EtI. The reactions followed second-order kinetics, rate = k 2 [ 1 ][RI], and the rates in the polar solvent acetone were faster than those in the nonpolar solvent toluene. Activation parameters have been determined and large negative values for Δ S ‡ were obtained. The results were also confirmed using DFT calculations. The computational investigations were used to determine the geometry of the species involved in the suggested mechanism and energy barriers. [ABSTRACT FROM AUTHOR]