Substitution reactions involving cyclometalated platinum(II) complexes: Kinetic investigations

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• 作者：S. Masoud Nabavizadeh  ; ;   ; ^{nabavi@chem.susc.ac.ir} ; Hamid R. Shahsavari ; Masoud Namdar ; Mehdi Rashidi  ; ;   ; ^{rashidi@chem.susc.ac.ir}
• 关键词：Cyclometalation ; Organoplatinum ; Substitution ; Kinetics ; Mechanism
• 刊名：Journal of Organometallic Chemistry
• 出版年：2011
• 出版时间：1 November 2011
• 年：2011
• 卷：696
• 期：22
• 页码：3564-3571
• 全文大小：391 K

文摘

Substitution reaction of the labile SMe₂ ligand in the cyclometalated platinum(II) complexes of general formula [PtAr(ppy)(SMe₂)], 1, in which ppy?=?deprotonated 2-phenylpyridyl and Ar?=?p-MeC₆H₄ or p-MeOC₆H₄, by several N or P donor reagents were studied; the N-donors, N, are pyridine (Py) and substituted pyridines, N?=?4-MePy, Py, Py-d₅, 2-MePy, 3-PhPy, 3,4-Me₂Py, 4-^tBuPy or 3-C(O)OMePy, and the P-donors, L, are phosphines or phosphites, L?=?P(OPh)₃, P(O-ⁱPr)₃, PPh₃, PPh₂Me and L₂?=?Ph₂PCH₂PPh₂, bis(diphenylphosphino)methane (dppm). The products were identified by multinuclear NMR studies as [PtAr(ppy)(N)], 2, or [PtAr(ppy)(L)], 3, respectively. Complexes 1 have a MLCT band in the visible region which was used to easily follow the kinetics of the ligand substitution reactions by UV¨Cvis spectroscopy. Although the complexes 1 contain two cis Pt¨CC bonds, the substitution reactions followed a normal associative mechanism. The rates of reactions were depended on the concentration and the nature of the entering group. The ¦¤H^{?/sup>/¦¤S?/sup> compensation plot gave a straight line suggesting the operation of the same mechanism for all entering nucleophiles.}