Premium
Carbon‐iodide bond activation by cyclometalated Pt (II) complexes bearing tricyclohexylphosphine ligand: A comparative kinetic study and theoretical elucidation
Author(s) -
Chamyani Samira,
Shahsavari Hamid R.,
Abedanzadeh Sedigheh,
Golbon Haghighi Mohsen,
Shabani Sepideh,
Notash Behrouz
Publication year - 2019
Publication title -
applied organometallic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 71
eISSN - 1099-0739
pISSN - 0268-2605
DOI - 10.1002/aoc.4674
Subject(s) - chemistry , oxidative addition , deprotonation , tricyclohexylphosphine , ligand (biochemistry) , steric effects , cyclopentadiene , phosphine , reductive elimination , medicinal chemistry , nuclear magnetic resonance spectroscopy , stereochemistry , catalysis , organic chemistry , ion , biochemistry , receptor
Cyclometalated Pt (II) complexes [PtMe(C^N)(L)], in which C^N = deprotonated 2,2′‐bipyridine N ‐oxide (Obpy), 1 , deprotonated 2‐phenylpyridine (ppy), 2 , deprotonated benzo [h] quinolone (bzq), 3 , and L = tricyclohexylphosphine (PCy 3 ) were prepared and fully characterized. By treatment of 1–3 with excess MeI, the thermodynamically favored Pt (IV) complexes cis ‐[PtMe 2 I(C^N)(PCy 3 )] (C^N = Obpy, 1a ; ppy, 2a ; and bzq, 3a ) were obtained as the major products in which the incoming methyl and iodine groups adopted cis positions relative to each other. All the complexes were characterized by means of NMR spectroscopy while the absolute configuration of 1a was further determined by X‐ray crystal structure analysis. The reaction of methyl iodide with 1–3 were kinetically explored using UV–vis spectroscopy. On the basis of the kinetic data together with the time‐resolved NMR investigation, it was established that the oxidative addition reaction occurred through the classical S N 2 attack of Pt (II) center on the MeI reagent. Moreover, comparative kinetic studies demonstrated that the electronic and steric nature of either the cyclometalating ligands or the phosphine ligand influence the rate of reaction. Surprisingly, by extending the oxidative addition reaction time, very stable iodine‐bridged Pt (IV)‐Pt (IV) complexes [Pt 2 Me 4 (C^N) 2 ( μ ‐I) 2 ] (C^N = Obpy, 1b ; ppy, 2b ; and bzq, 3b ) were obtained and isolated. In order to find a reasonable explanation for the observation, a DFT (density functional theory) computational analysis was undertaken and it was found that the results were consistent with the experimental findings.