Details

Autor(en) / Beteiligte

• Bouley, Bailey S
• Tang, Fengzhi
• Bae, Dae Young
• Mirica, Liviu M

Titel

C-H bond activation via concerted metalation-deprotonation at a palladium(iii) center

Ist Teil von

• Chemical science (Cambridge), 2023-04, Vol.14 (14), p.3800-3808

Ort / Verlag

England: Royal Society of Chemistry

Erscheinungsjahr

2023

Link zum Volltext

Quelle

Free E-Journal (出版社公開部分のみ）

Beschreibungen/Notizen

• Herein we report the direct observation of C-H bond activation at an isolated mononuclear Pd(iii) center. The oxidation of the Pd(ii) complex ( N4)Pd (neophyl)Cl (neophyl = -CH C(CH ) Ph; N4 = , '-dimethyl-2,11-diaza[3.3](2,6)pyridinophane) using the mild oxidant ferrocenium hexafluorophosphate (FcPF ) yields the stable Pd(iii) complex [( N4)Pd (neophyl)Cl]PF . Upon the addition of an acetate source, [( N4)Pd (neophyl)Cl]PF undergoes Csp -H bond activation to yield the cyclometalated product [( N4)Pd (cycloneophyl)]PF . This metalacycle can be independently prepared, allowing for a complete characterization of both the starting and final Pd(iii) complexes. The C-H activation step can be monitored directly by EPR and UV-Vis spectroscopies, and kinetic isotope effect (KIE) studies suggest that either a pre-association step such as an agostic interaction may be rate limiting, or that the C-H activation is partially rate-limiting in conjunction with ligand rearrangement. Density functional theory calculations support that the reaction proceeds through a κ ligand coordination and that the flexible ligand structure is important for this transformation. Overall, this study represents the first example of discrete C-H bond activation occurring at a Pd(iii) center through a concerted metalation-deprotonation mechanism, akin to that observed for Pd(ii) and Pd(iv) centers.