Chang Wei-Chieh, Deufel Fritz, Weyhermüller Thomas, Farès Christophe, Werlé Christophe
Max Planck Institute for Chemical Energy Conversion Stiftstr. 34-36 45470 Mülheim an der Ruhr Germany
Ruhr University Bochum Universitätsstr. 150 44801 Bochum Germany.
RSC Adv. 2021 Nov 22;11(59):37383-37391. doi: 10.1039/d1ra07126b. eCollection 2021 Nov 17.
Proazaphosphatranes are intriguing ligand architectures comprising a bicyclic cage of flexible nature. They can undergo structural deformations due to transannulation while displaying modular electronic and steric properties. Herein, we report the synthesis and coordination chemistry of rhodium(i) complexes bearing a tris(isopropyl)-azaphosphatrane (TPrAP) ligand. The molecular structure of the primary complex (1) revealed the insertion of the metal center into a P-N bond of the ligand. The addition of a Lewis acid, , lithium chloride, promoted the dynamic behavior of the complex in the solution, which was studied by state-of-the-art NMR spectroscopy. Substituting the cyclooctadiene ligand at the metal center with triphenylphosphine or 2-pyridyldiphenylphosphine unveiled the adaptive nature of the TPrAP backbone capable of switching its axial nitrogen from interacting with the phosphorus atom to coordinate the rhodium center. This led the entire ligand edifice to change its binding to rhodium from a bidentate to tridentate coordination. Altogether, our study shows that introducing a TPrAP ligand allows for unique molecular control of the immediate environment of the metal center, opening perspectives in controlled bond activation and catalysis.
原氮磷杂三环是一种引人注目的配体结构，由具有柔性的双环笼状结构组成。它们可因跨环作用而发生结构变形，同时展现出模块化的电子和空间性质。在此，我们报道了带有三（异丙基）氮磷杂三环（TPrAP）配体的铑（I）配合物的合成及配位化学。主配合物（1）的分子结构表明金属中心插入到了配体的P-N键中。加入路易斯酸氯化锂可促进该配合物在溶液中的动态行为，这通过最先进的核磁共振光谱进行了研究。用三苯基膦或2-吡啶基二苯基膦取代金属中心的环辛二烯配体，揭示了TPrAP主链的适应性本质，即其轴向氮能够从与磷原子相互作用转变为与铑中心配位。这使得整个配体结构与铑的结合从双齿配位转变为三齿配位。总之，我们的研究表明引入TPrAP配体能够对金属中心的紧邻环境进行独特的分子控制，为可控键活化和催化开辟了前景。
