دانشگاه تحصیلات تکمیلی علوم پایه زنجان

بلوار استاد یوسف ثبوتی، پلاک 444

صندوق پستی 1159-45195 زنجان 66731-45137 ایران

دورنگار: 33155142 -024

تلفن: 33151 -024


طراحی و برنامه نويسی توسط مركز كامپيوتر دانشگاه تحصيلات تكميلي علوم پايه زنجان

خانه>دانشکده شیمی>
دانشکده شیمی
 
 
1- Shahsavari, H. R., Babadi Aghakhanpour, R., Fereidoonnezhad, M., "An in-depth investigation on the C–I bond activation by rollover cycloplatinated(II) complexes bearing monodentate phosphane ligands: kinetic and kinetic isotope effect ", New Journal of Chemistry, 42: (4), 2564-2573, (2018).

Abstract:
In this study, a series of platinum(II) complexes with the general formula of [Pt(O-bpy)(Me)(L)], 1, O-bpy = cyclometalated rollover 2,2′-bipyridine N-oxide and L = PPh3 (1a), PPh2Me (1b) and PPhMe2 (1c) was prepared. The oxidative addition reaction of MeI reagent to the Pt(II) center was performed and kinetically investigated. In the Pt(II) → trans-Pt(IV) reaction (kinetic product), the electronic effects of the phosphanes determine the rates of the reactions and the following trend was obtained: PPhMe2 > PPh2Me > PPh3. However, in the trans-Pt(IV) → cis-Pt(IV) isomerization (thermodynamic product), the steric effects induced by phosphane ligands controlled the conversion rates (PPh3 > PPh2Me > PPhMe2). Also, a secondary α-deuterium kinetic isotope effect (KIE) study was performed for some of the reactions using the CD3I reagent. The obtained small KIE values are indicative of a classic SN2 mechanism with a tight transition state. Moreover, the reactions of 1a with MeI and CD3I were monitored by (1H and 31P{1H}) NMR spectroscopy in order to gain an appropriate proposed mechanism. The NMR monitoring data for CD3I exhibited the presence of scrambling twins in which the incoming CD3 ligand occupies the CH3 ligand position in the parent Pt(II) complex and vice versa. 1a, containing PPh3 ligand, indicated the mentioned scrambling for both trans and cis products. However, the trans to cis isomerization for 1b (PPh2Me) and 1c (PPhMe2) was very slow, so NMR data showed the scrambling only for trans geometry.