Oxygen Binding to [Pd(L)(L鈥?] (L= NHC, L鈥?= NHC or PR3, NHC = N-Heterocyclic Carbene). Synthesis and Structure of a Paramagnetic trans-[Pd(NHC)2(畏1-O
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- 作者：Xiaochen Cai ; Subhojit Majumdar ; George C. Fortman ; Catherine S. J. Cazin ; Alexandra M. Z. Slawin ; Charles Lhermitte ; Rajeev Prabhakar ; Meaghan E. Germain ; Taryn Palluccio ; Steven P. Nolan ; Elena V. Rybak-Akimova ; Manuel Temprado ; Burjor Captain ; Carl D. Hoff
- 刊名：Journal of the American Chemical Society
- 出版年：2011
- 出版时间：February 9, 2011
- 年：2011
- 卷：133
- 期：5
- 页码：1290-1293
- 全文大小：775K
- 年卷期：v.133,no.5(February 9, 2011)
- ISSN：1520-5126
文摘
The reactivity of a number of two-coordinate [Pd(L)(L鈥?] (L = N-heterocyclic carbene (NHC) and L鈥?= NHC or PR3) complexes with O2 has been examined. Stopped-flow kinetic studies show that O2 binding to [Pd(IPr)(P(p-tolyl)3)] to form cis-[Pd(IPr)(P(p-tolyl)3)(畏2-O2)] occurs in a rapid, second-order process. The enthalpy of O2 binding to the Pd(0) center has been determined by solution calorimetry to be 鈭?6.2(1.9) kcal/mol. Extension of this work to the bis-NHC complex [Pd(IPr)2], however, did not lead to the formation of the expected diamagnetic complex cis-[Pd(IPr)2(畏2-O2)] but to paramagnetic trans-[(Pd(IPr)2(畏1-O2)2], which has been fully characterized. Computational studies addressing the energetics of O2 binding have been performed and provide insight into reactivity changes as steric pressure is increased.