2026-10-06T04:29:02Z https://api.figshare.com/v2/oai

oai:figshare.com:article/34050180 2026-10-01T18:09:02Z category_1 category_4 category_7 category_16 category_21 category_272 category_873 category_734 portal_63 item_type_6 month_year_10_2026

C–H Activations with a T‑Shaped 14 Electron PNP-Rhodium(I) Complex: Step-by-Step Formation and Reactivity of (Vinylidene)rhodium Complexes Leon K. Paschai Darian (14671686) Marla Waldenmaier (25158162) Jiska Dannenberger (25158165) Joachim Ballmann (1616461) Carsten Wolf (25158168) Lutz H. Gade (1353462) Biophysics Biochemistry Medicine Physiology Biotechnology Environmental Sciences not elsewhere classified Chemical Sciences not elsewhere classified Biological Sciences not elsewhere classified substrate oxidatively added isolable corresponding alkynyl hydrogen shift mechanism enabled easy monitoring intermediate (< b 6 </ sub 5b </ b 5a </ b 4 </ sub 2b </ b 2 </ sub vinylidene generation via coordinated alkyne complexes 1 </ b terminal alkyne coordinated vinylidene vinylidene complexes step monitoring toward electrophiles remarkable inertness reactive 14 preceding η kinetic measurements intramolecular conversion herein report dft modeling dft calculations centered conversion 5 kcal We herein report the synthesis and characterization of a series of PNP-coordinated rhodium vinylidene complexes with a carbazole-based PNP pincer ligand framework. The availability of the reactive 14-valence electron [(PNP)Rh^I] complex <b>1</b> allowed a step-by-step monitoring of the metal-centered conversion of the terminal alkyne to the coordinated vinylidene. In a first step, the R–C≡CH (R = H, Ph, C₆H₄F, cyclohex-1-enyl) substrate oxidatively added to <b>1</b> to form an isolable corresponding alkynyl(hydrido)rhodium(III) intermediate (<b>2a</b>–<b>5a</b>), from which intramolecular conversion to the vinylidene complexes <b>2b</b>–<b>5b</b> occurred. The equilibrium of <b>2a</b>–<b>5a</b> with the preceding η²-π-coordinated alkyne complexes was not observed, the latter being destabilized by >5 kcal/mol as indicated by DFT modeling. This enabled easy monitoring of the vinylidene generation via a 1,3-hydrogen shift mechanism, as evidenced by kinetic measurements in combination with DFT calculations. Some aspects of the reactivity of the parent Rh=C=CH₂ vinylidene complex <b>2b</b> toward electrophiles and nucleophiles was investigated, uncovering a remarkable inertness of the vinylidene-rhodium unit in <b>2b</b>. 2026-10-01T00:00:00Z Text Journal contribution 10.1021/acs.inorgchem.6c04437.s001 https://figshare.com/articles/journal_contribution/C_H_Activations_with_a_T_Shaped_14_Electron_PNP-Rhodium_I_Complex_Step-by-Step_Formation_and_Reactivity_of_Vinylidene_rhodium_Complexes/34050180 CC BY-NC 4.0