Laser photolysis studies of the reaction of chromium(III) octaethylporphyrin complex with triphenylphosphine and triphenylphosphine oxide
Laser photolysis studies of the reaction of chromium(III) octaethylporphyrin complex with triphenylphosphine and triphenylphosphine oxide
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DOI：
10.1021/ic0504487
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发表时间：
2005-09-05
影响因子：
4.6
通讯作者：
Hoshino, M
中科院分区：
文献类型：
--
作者：
Inamo, M;Matsubara, N;Hoshino, M
用激光闪光光解技术研究了八乙基卟啉合铬[Cr（OEP）（Cl）（L）]（L = H_2O，Py，OPPh_3）在二氯甲烷中的光反应.激光辐照导致配位不饱和中间体[Cr（OEP）（Cl）]的产生，其与溶液中的配体反应以产生母体络合物[Cr（OEP）（Cl）（L）]，或当L = Py或OPPh3时，产生瞬态物质[Cr（OEP）（Cl）（H2O）1。一旦产生[Cr（OEP）（Cl）（H2O）]，最终将轴向H2O配体与L交换以再生[Cr（OEP）（Cl）（L）]。的动力学，轴向配体取代反应，其次是cachometrically，和配体浓度依赖性的配体交换速率表明，该反应发生通过一个有限的解离机制。过量PPh3的[Cr（OEP）（Cl）（OPPh3）]在本体溶液中的光反应导致PPh3分子与铬离子的不利配位，从而产生瞬态配合物[Cr（OEP）（Cl）（PPh3）]。根据[Cr（OEP）（Cl）（PPh3）1在溶液中的离解和缔合反应的动力学参数，结合配合物分子结构的空间位阻性质，讨论了[Cr（OEP）（Cl）（PPh3）1在溶液中的动力学和热力学性质.
The photoreaction of the chromium(III) octaethylpoprhyrin complex, [Cr(OEP)(Cl)(L)] (L = H2O, Py, OPPh3), in dichloromethane was studied using laser flash photolysis technique. Laser irradiation causes the generation of a coordinately unsaturated intermediate [Cr(OEP)(Cl)], which reacts with ligands in solution to give the parent complex, [Cr(OEP)(Cl)(L)], or a transient species, [Cr(OEP)(Cl)(H2O)1, when L = Py or OPPh3. Once produced [Cr(OEP)(Cl)(H2O)] eventually exchanges the axial H2O ligand with L to regenerate [Cr(OEP)(Cl)(L)]. The kinetics, of the axial ligand substitution reaction was followed spectrophotometrically, and the ligand-concentration dependence of the ligand exchange rate revealed that the reaction occurs via a limited dissociative mechanism. The photoreaction of [Cr(OEP)(Cl)(OPPh3)] containing excess PPh3 in the bulk solution leads to the unfavorable coordination of the PPh3 molecule to the chromium ion to give a transient complex, [Cr(OEP)(Cl)(PPh3)]. The dynamic and thermodynamic properties of [Cr(OEP)(Cl)(PPh3)1 in solution are discussed on the basis of the kinetic parameters of the dissociation and association reactions of the PPh3 ligand together with the steric aspect of the molecular structure of the related complexes.