Andreatta Jeremy R, Cieslinski G Benjamin, Batool Madeeha, Sun Xue-Zhong, George Michael W, Brothers Edward N, Darensbourg Donald J, Bengali Ashfaq A
Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, USA.
Inorg Chem. 2009 Aug 17;48(16):7787-93. doi: 10.1021/ic900724f.
The displacement of eta(2)-coordinated ligands from the photolytically generated CpMn(CO)(2)L and BzCr(CO)(2)L [Cp = eta(5)-C(5)H(5), Bz = eta(6)-C(6)H(6), L = 2,3-dihydrofuran (DHF), furan] complexes by pyridine has been studied. The displacement reactions span a wide range of time scales from microseconds to hours and were studied using a range of time-resolved IR spectroscopic techniques. The substitution reactions follow a dissociative pathway and the measured activation enthalpies provide an estimate for the strength of the metal-(eta(2)-furan) and metal-(eta(2)-DHF) interactions. In these complexes, the Cr center binds both ligands weaker than the Mn center. There is a approximately 6-10 kcal/mol difference in the binding enthalpies of eta(2)-furan and eta(2)-DHF to both metals suggesting that this difference is the result of a partial loss of resonance energy in the case of the aromatic furan ligand upon interaction with the metal.
研究了吡啶对光解生成的 CpMn(CO)₂L 和 BzCr(CO)₂L [Cp = η⁵-C₅H₅，Bz = η⁶-C₆H₆，L = 2,3-二氢呋喃 (DHF)，呋喃] 配合物中 η² 配位配体的取代情况。取代反应的时间尺度范围很广，从微秒到小时不等，并使用一系列时间分辨红外光谱技术进行了研究。取代反应遵循解离途径，测得的活化焓为金属-(η²-呋喃)和金属-(η²-DHF)相互作用的强度提供了一个估计值。在这些配合物中，Cr 中心与两种配体的结合都比 Mn 中心弱。η²-呋喃和 η²-DHF 与两种金属的结合焓存在约 6-10 kcal/mol 的差异，这表明这种差异是芳香族呋喃配体与金属相互作用时共振能量部分损失的结果。
