Four new triphenylphosphine-derived cage ligands were modularly synthesized via dynamic imine chemistry (DIC), and their absolute structures were characterized by single crystal X-ray diffraction (SXRD), nuclear magnetic resonance (NMR) and high resolution mass spectroscopy (HRMS). In contrast to small-molecule analogues, cage ligands demonstrate superior activity and selectivity. The Rh/Cage-L2 catalyst exhibits remarkable performance with an aldehyde selectivity of 89%, accompanied by a TOF value of 2665 h⁻¹ and an l/b ratio of 2.60, thereby showcasing leading activity, chemical selectivity, and regioselectivity in the realm of homogeneous catalysts that rely on triphenylphosphine ligands. The reason for the formation of a higher l/b ratio, with a 3.84 kJ mol⁻¹ difference in the energy of the rate-determining step, has been explained through density functional theory (DFT) calculations. In addition, a Janus-type PPh₃-Au complex has been discovered during the study of the coordination of cage ligands, offering partial corroboration for the single coordination mechanism of these cage ligands. The large steric hindrance effect of cage ligands is believed to play a pivotal role in the hydroformylation reaction. This work highlights the potential application of cage ligands and inspires future efforts in the search of highly selective and efficient organometallic catalysts.

中文翻译：

---

三苯基膦衍生的笼式配体的模块化合成，用于铑催化的加氢甲酰化应用


通过动态亚胺化学 （DIC） 模块化合成了 4 种新的三苯基膦衍生的笼式配体，并通过单晶 X 射线衍射 （SXRD）、核磁共振 （NMR） 和高分辨率质谱 （HRMS） 表征了它们的绝对结构。与小分子类似物相比，笼式配体表现出优异的活性和选择性。Rh/Cage-L2 催化剂表现出卓越的性能，醛选择性为 89%，TOF 值为 2665 ^h-1，l/b 比为 2.60，从而在依赖三苯基膦配体的均相催化剂领域中表现出领先的活性、化学选择性和区域选择性。形成较高 l/b 比的原因，速率确定步骤的能量差异为 3.84 kJ ^mol-1，已通过密度泛函理论 （DFT） 计算解释。此外，在研究笼式配体的配位过程中发现了一种 Janus 型 PPh_3-Au 复合物，为这些笼式配体的单一配位机制提供了部分佐证。笼式配体的大空间位阻效应被认为在加氢甲酰化反应中起关键作用。这项工作突出了笼式配体的潜在应用，并激发了未来寻找高选择性和高效有机金属催化剂的努力。