Jordan Emma J, Calder Ethan D E, Greene Bethan L, Adcock Holly V, Male Louise, Davies Paul W, Jupp Andrew R
School of Chemistry, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom.
Organometallics. 2024 Sep 6;43(20):2674-2685. doi: 10.1021/acs.organomet.4c00302. eCollection 2024 Oct 28.
The design and tuning of new ligands is crucial for unlocking new reactivity at transition metal centers. Azophosphines have recently emerged as a new class of 1,3-P,N ligands in ruthenium piano-stool complexes. This work shows that the azophosphine synthesis can tolerate -aryl substituents with strongly electron-donating and electron-withdrawing -R groups and that the nature of this R group can affect the spectroscopic and structural properties of the azophosphines, as measured by NMR spectroscopy, UV-vis spectroscopy, single-crystal X-ray diffraction, and DFT studies. Azophosphines are shown to be relatively weak phosphine donors, as shown by analysis of the coupling constants of the corresponding azophosphine selenides, but the donor properties can be fine tuned within this area of chemical space. Monodentate and bidentate Ru-azophosphine complexes were prepared, and their first use as a catalyst was probed. The Ru-azophosphine complexes were found to promote the transfer hydrogenation of acetophenone to 1-phenylethanol without the requirement of a harsh base additive, and the bidentate complex was more active than the monodentate analogue.
新型配体的设计与调控对于激发过渡金属中心的新反应活性至关重要。氮膦最近作为钌钢琴凳配合物中的一类新型1,3 - P,N配体出现。这项工作表明，氮膦的合成能够耐受带有强供电子和吸电子 -R基团的 -芳基取代基，并且该R基团的性质会影响氮膦的光谱和结构性质，这通过核磁共振光谱、紫外 - 可见光谱、单晶X射线衍射和密度泛函理论研究得以测定。通过对相应氮膦硒化物的耦合常数分析表明，氮膦是相对较弱的膦供体，但在这个化学空间范围内，供体性质可以进行微调。制备了单齿和双齿钌 - 氮膦配合物，并对它们作为催化剂的首次应用进行了探索。发现钌 - 氮膦配合物能够促进苯乙酮向1 - 苯乙醇的转移氢化反应，而无需苛刻的碱添加剂，并且双齿配合物比单齿类似物更具活性。
