100995-38-8

Upstream product

• 100995-31-1 W(CO)3(PCy₃)2(py) 
• 121-45-9 phosphorous acid trimethyl ester 
• 73690-56-9 (P(C₆H₁₁)3)2W(CO)3 
• 104198-75-6 W(CO)3(PCy₃)2(H₂) 
• 73690-57-0 W(CO)3(PCy₃)2(N₂) 

Relevant academic research and scientific papers

Rate of reaction of (P(C6H11)3)2W(CO)3 with py, P(OMe)3, PPh2Me, and 2,6-Me2py. Stopped-flow kinetic study of concerted reactions at a sterically crowded metal center

The rate of reaction of the complexes (P(C6H11)3)2W(CO)3 and (P(C6D11)3)2W(CO)3 with P(OMe)3 have been measured by stopped-flow kinetics. At 25°C the hydrogen-substituted complex follows second-order kinetics with k = 5.45 × 104 M-1 s-1 and ΔH≠ = 4.2 kcal/mol. An inverse kinetic isotope effect is observed with k(H)/k(D) = 0.87. The ligand PPh2Me reacts 3 times more slowly than P(OMe)3 and shows a larger inverse kinetic isotope effect, k(H)/k(D) = 0.78. Reaction of (P(C6H11)3)2W(CO)3 with 2,5-dimethylpyridine occurs with the rate constant 8.6 × 103 M-1 s-1 at 257deg;C, 2 orders of magnitude slower than the reaction with pyridine. The unusually high selectivity is ascribed to steric factors at the crowded metal center. New stopped-flow data at low pyridine concentrations are reported for dissociation of pyridine from the complexes (P(C6H11)3)2W(CO)3(py) and (P-(C6D11)3)2W(CO)3(py). A primary kinetic isotope effect k1(H)/k1(D) = 1.19 is observed in these reactions. These results imply that, in spite of the steric crowding at the metal center, dissociation of pyridine is assisted by partial formation of the W?H "agostic" bond in the transition state.

Thermodynamic and kinetic studies of the complexes W(CO)3(PCy3)2(L) (L = H2, N2, NCCH3, Pyridine, P(OMe)3, CO)

The complexes W(CO)3(PCy3)2(L) have been studied by solution calorimetry. The enthalpies of binding (kcal/mol) of ligands to W(PCy3)2(CO)3 in toluene solution are as follows: H2, -9.9, N2, -13.5; NCCH3, -15.1; pyridine, -18.9; P(OMe)3, -26.5; CO, -30.4. Similar values are obtained in tetrahydrofuran solution. These data imply bond strengths much lower than expected from gas-phase studies. The origin of this discrepancy is attributed to the presence of the W...H-C 'agostic' interaction. This is estimated to be on the order of 10±6 kcal/mol. In order to investigate the role of the 'agostic' interaction in the energetics of this complex, the kinetics of reaction of W(CO)3[P(C6H11)3]2(py) and W(CO)3[P(C6D11)3]2(py) with P(OMe)3 in toluene were studied. A kinetic isotope effect, kH/kD=1.20±0.05, was observed, and verifies the importance of the 'agostic' bond in ligand substitution for this complex. A mechanism is proposed that involves concrete replacement of coordinated pyridine by the three-center W...H-C bond.