Electronic Effect of Ligands on the Stability of Nickel–Ketene Complexes

Abstract

Electronically variant (dppf)Ni(ketene) complexes were synthesized and characterized to perform kinetic analysis on their decomposition through a decarbonylation/disproportion process to Ni− CO complexes and alkenes. Ligands containing electron-donating groups stabilized such complexes, whereas an electron-withdrawing group was found to destabilize them. Hammett analysis on the decomposition reaction revealed the buildup of negative charges in the rate-determining step, which corroborates past computational models.

Photochemical Activation of a Hydroxyquinone-Derived Phenyliodonium Ylide by Visible Light: Synthetic and Mechanistic Investigations

“…1 H NMR (600 MHz, DMSO-d 6 ) δ 7.81 (d, J = 7.7 Hz, 2H), 7.52 (t, J = 7.3 Hz, 1H), 7.40 (t, J = 7.7 Hz, 2H), 6.94 (d, J = 10.0 Hz, 1H), 6.62 (d, J = 10.0 Hz, 1H) ppm. 13 2-Cyclopentene-1,4-dione (3a). CH 3 CN (200 mL) was added to a 250 mL round-bottomed flask containing compound 1a (2.00 g, 6.13 mmol) and a stir bar in air.…”

“…2 1 H NMR (600 MHz, CDCl 3 ) δ 7.30 (s, 2H), 2.90 (s, 2H) ppm. 13 C{ 1 H} NMR (150 MHz, CDCl 3 ) δ 199.7, 149.5, 40.5 ppm.…”

“…47 1 H NMR (600 MHz, CDCl 3 ) δ 7.86 (d, J = 7.3 Hz, 2H), 7.54−7.44 (complex m, 3H), 7.07 (s, 1H), 6.77 (d, J = 10.3 Hz, 1H), 6.73 (d, J = 10.4 Hz, 1H) ppm. 13 General Procedure A: Synthesis of Compounds 7. In air, THF (5 mL) was added to a 20 mL screw-top vial containing compound 1a (30 mg, 92 μmol), the azodicarboxylate ester 6 (613 μmol), and a stir bar.…”

“…48 1 H NMR (600 MHz, CDCl 3 ) δ 6.60− 6.28 (m, 1H), 5.96 (br s, 1H), 4.91 (sept, J = 6 Hz, 2H), 3.95 (q, J = 6.9 Hz, 1H), 3.71 (q, J = 6.9 Hz, 1H), 2.11−1.77 (complex m, 4H), 1.21 (br s, 12H) ppm. 13 Di-tert-butyl 1-(tetrahydrofuran-2-yl)hydrazine-1,2-dicarboxylate (7b). This reaction employed di-tert-butyl azodicarboxylate and followed General Procedure A.…”

“…49 1 H NMR (600 MHz, CDCl 3 ) δ 6.18 (br s, 1H), 5.95 (m, 1H), 3.99 (m, 1H), 3.77 (m, 1H), 2.07−2.00 (m, 3H), 1.83 (m, 1H), 1.49 (br s, 18H) ppm. 13 Dibenzyl 1-(tetrahydrofuran-2-yl)hydrazine-1,2-dicarboxylate (7c). This reaction employed dibenzyl azodicarboxylate and followed General Procedure A.…”