Intramolecular Exchange of Coordinated and Dangling Phosphine Groups in Pentacarbonyl[(diphenylphosphino)(di-p-tolylphosphino)methane]tungsten(0)

Synthesis of P,P-bidentate caged phosphines via tungsten pentacarbonyl-promoted cycloaddition reactions of 1-alkyl-1,2-diphospholes

“…We decided to study this phenomenon in more detail, drawing upon existing literature concerning the migration of the W(CO) 5 group between the two phosphorus atoms. [30][31][32][33] 1-Isopropyl-1,2-diphosphole (1b) reacts with in situ generated [W(CO) 5 (THF)] in THF at 0 1C to give complex 2b. Despite the steric hindrance posed by the isopropyl group and the W(CO) 5 fragment at the two phosphorus atoms, 2b displays significantly broadened signals in the 31 P{ 1 H} NMR spectrum at room temperature, indicating a dynamic process on the NMR time scale (Scheme 2).…”

“…All solvents were distilled from sodium/benzophenone or phosphorus pentoxide and stored under nitrogen before use. The NMR spectra were recorded on a Bruker MSL-400 ( 1 H 400 MHz, 31 P 161.7 MHz, 13 C 100.6 MHz). 1 H and 13 C NMR data are reported with reference to solvent resonances, and 31 P NMR spectra were reported with respect to external 85% H 3 PO 4 (0 ppm).…”

“…1 H NMR (CDCl 3 , 293 K, d, ppm): 0.98 (t, 6H, CH 3 , 3 J HH = 7.06 Hz), 1.52 (m, 1H, CH), 6.9-7.8 (m, 15H, Ph). 31 tungsten(0) (2a) (0.44 g, 0.65 mmol) in 10 mL toluene. The reaction mixture was stirred for 5 h at 110 1C.…”

Dangling phosphine complexes: Phosphine exchange in pentacarbonyl tungsten complexes of bis(diphenylphosphinomethyl)phenylphosphine

“…Table 1 shows 4 J PC values and solid state distances between pendant phosphines and the carbon atoms of the closest carbonyl group for several complexes. In addition to the complexes listed in Table 1, cis 4 J PC coupling has been observed in [(OC) 5 W{k 1 -PPh 2 CH 2 P(p-tol) 2 }] (3.2 Hz), [(OC) 5 W{k 1 -P(ptol) 2 CH 2 PPh 2 }] (2.9 Hz), and [(OC) 5 W{k 1 -P(p-tol) 2 CH 2 P(p-tol) 2 }] (2.8 Hz) [20,21]. An examination of four-bond PeC couplings reported in the literature suggests that our values, while comparable to those involving pi bonds [22], are larger than expected for systems involving sigma bonds.…”

“…Evidence suggests that 13a, also lacking a second pendant arm, follows a 1,2-shift mechanism with the intermediate relative rate resulting from the close proximity of its one pendant arm to the carbonyl plane [20].…”