η5-Cyclopentadienyl-η3-1-phenylallylpalladium

[105333-10-6] C14H14Pd (MW 288.68) InChI = 1S/C9H9.C5H5.Pd/c1-2-6-9-7-4-3-5-8-9;1-2-4-5-3-1;/h2-8H,1H2;1-5H; InChIKey = STDKYMKMBSTDJK-UHFFFAOYSA-N (reacts with a variety of phosphines L to reductively eliminate C14H14 and form palladium(0) compounds of the type PdL21. The latter are believed to be the catalytic species in many cross-coupling reactions, and η5-cyclopentadienyl-η3-1-phenylallylpalladium (I) is the only readily available precatalyst known to effect quantitative PdL2 formation for use in cross-coupling reactions1) Physical Data: mp 45 °C (dec.). Solubility: soluble in most types of organic solvents. Analysis of Reagent Purity: 1H NMR spectrum (600 MHz, toluene-d8): δ 2.16 (d, J 10.5 Hz, 1H), 3.36 (d, J 6.1 Hz, 1H), 3.84 (d, 9.8 Hz, 1H), 5.14 (ddd, J 6.1 Hz, 9.8 Hz, 10.5 Hz, 1H), 5.63 (s, 5H), 6.98–7.03 (m, 3H), 7.24–7.27 (m, 2H). Form Supplied in: deep purple-red crystals; commercially available. Preparative Methods:1 all steps were carried out under an atmosphere of purified argon using solvents dried by passage through activated alumina columns (Innovative Technology Solvent Purification System) and then stored over 3A molecular sieves dried under reduced pressure at 225 °C. A solution of sodium cyclopentadienide in THF (2.0 M, Aldrich) (1.45 mL, 2.90 mmol), diluted with 20 mL THF in a dropping funnel, was added dropwise to a stirred suspension of [Pd(η3-1-Ph-C3H4)Cl]22 (0.60 g, 1.16 mmol) in 20 mL THF at −78 °C. The resulting deep purple solution was stirred for 30 min, and then warmed to room temperature. The solvent was removed at room temperature under reduced pressure and the resulting solid product was extracted using three 20 mL portions of hexanes. The filtrate was reduced under reduced pressure, yielding an oily purple solid that was dissolved in ∼5 mL hexanes at room temperature. The resulting solution was cooled at −35 °C to give purple crystals that were collected by filtration. Yield: 0.565 g, 84%. Purple-red crystals can also be obtained by sublimation at 40 °C, 1 × 10−3 Torr. Handling, Storage, and Precautions: although heating during synthesis and workup can result in decomposition and palladium metal deposition, η5-cyclopentadienyl-η3-1-phenylallylpalladium (I) is, once prepared and purified, stable in solution for at least 30 min at 50 °C. Although long-term storage of I is probably best in a freezer, solutions are stable for several days under air at ambient temperatures.