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Combined Kinetico‐Mechanistic and Theoretical Elucidation of the Oxidative Addition of Iodomethane to Cycloplatinated(II) Complexes: Controlling the Rate of trans/cis Isomerization
Author(s) -
Shahsavari Hamid R.,
Babadi Aghakhanpour Reza,
Babaghasabha Mojgan,
Golbon Haghighi Mohsen,
Nabavizadeh S. Masoud,
Notash Behrouz
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201700088
Subject(s) - chemistry , isomerization , oxidative addition , deprotonation , reaction mechanism , nuclear magnetic resonance spectroscopy , spectroscopy , density functional theory , photochemistry , medicinal chemistry , stereochemistry , computational chemistry , catalysis , organic chemistry , ion , physics , quantum mechanics
The oxidative addition of iodomethane to cycloplatinated(II) complexes containing allyldiphenylphosphane (PPh 2 allyl) ligands, namely, [Pt(C ^ N)Me(PPh 2 allyl)] [ 1 – 4 ; C ^ N = deprotonated 2‐phenylpyridyne (ppy), 1 ; 2,2′‐bipyridine (bpy), 2 ; 2,2′‐bipyridine N ‐oxide (O‐bpy), 3 ; and 7,8‐benzoquinoline (bzq), 4 ], occurs readily with trans stereochemistry to give the trans ‐Pt IV isomers 1a – 4a , which then transform slowly to the cis ‐Pt IV isomers 1b – 4b . All of the complexes were characterized by NMR spectroscopy, and the structures of 1b , 3a , and 3b were determined by single‐crystal X‐ray diffraction. Kinetic studies through UV/Vis spectroscopy suggested that the oxidative addition reaction proceeded through an S N 2 reaction. The rate of the oxidative addition reaction was measured at different temperatures, and large negative Δ S ≠ values consistent with the proposed mechanism were found for each reaction. This reaction was also monitored by NMR spectroscopy to determine a correct value for the rate of the trans/cis isomerization. The theoretical aspects of the mechanism for the oxidative addition reaction were also studied by density functional theory (DFT) calculations to support the claimed experimental results.