150697-17-9Relevant academic research and scientific papers
The Reversible Insertion Reaction of Carbon Dioxide with the W(CO)5OH- Anion. Isolation and Characterization of the Resulting Bicarbonate Complex [PPN][W(CO)5O2COH]
Darensbourg, Donald J.,Meckfessel Jones, Monica L.,Reibenspies, Joseph H.
, p. 4406 - 4413 (1996)
[Et4N][W(CO)5OH] (1) and [PPN][W(CO)5O2COH] (2) have been synthesized and characterized by 1H and 13C NMR and IR spectroscopies, and the X-ray crystal structure of 2 has been determined. Complex 2 crystallizes in the triclinic space group P1? with unit cell parameters a = 12.208(2) ?, b = 13.497(2) ?, c = 13.681(2) ?, α = 101.06(2)°, β = 114.76(1)°, γ = 98.45(2)°, V = 1942.6(5) ?3, and Z = 2. The structure of the anion of complex 2 consists of a central W(0) bound to five carbonyl ligands, and the coordination around the metal is completed by a monodentate bound bicarbonate ligand located 2.19(1) ? away from the metal center. In the solid state, two anions are hydrogen bonded to one another via the bicarbonate ligands in the unit cell. Complex 1 inserts CO2, COS, or CS2 to rapidly afford the corresponding bicarbonate or thiocarbonate complexes. The lower limit for the rate constant for the carboxylation of complex 1 has been determined to be 4.2 × 10-4 M-1 s-1 at -70.2 °C, and the lower limit for the rate constant for the decarboxylation of complex 2 has been found to be 2.5 × 10-3 s-1 at 20.0 °C. In addition, the rate constant for the decarbonylation of 2 was determined to be 7.60 × 10-3 s-1 at 36.0 °C, a value which is somewhat faster than anticipated on the basis of analogous data for a large variety of W(CO)5O2CR- derivatives. This is attributed to a diminution of the electron-withdrawing ability of the OH substituent in O2COH as a result of hydrogen bonding to solvent. Nevertheless, it is clear that the rate of decarboxylation of the anion from complex 2 is faster than the rate of CO dissociation. Concomitantly, carboxylation of complex 1 is faster than CO dissociation, since the W(CO)5OH- is inert toward 13CO exchange on the time scale of carboxylation at -70.2 °C.
