In situ high pressure NMR studies of Co{sub 2}(CO){sub 6}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} in supercritical carbon dioxide : ligand substitution, hydrogenation, and hydroformylation reactions.

Journal Article · Mon May 24 04:00:00 EDT 2004 · Organometallics

DOI:https://doi.org/10.1021/om030600h· OSTI ID:961431

Chen, M J; Klingler, R J; Rathke, J W; Kramarz, K W

The dimeric cobalt complex Co{sub 2}(CO){sub 6}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} (1) reacts reversibly with hydrogen to produce HCo(CO){sub 3}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}] (4). The carbonyl and the phosphine ligands of both 1 and 4 are very labile. Compound 1 reacts with CO to give Co{sub 2}(CO){sub 7}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}] (2), and compound 4 reacts with CO and P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3} (L) to give HCo(CO){sub 4} (5) and HCo(CO){sub 2}[P(p-CF{sub 3}C{sub 6}H{sub 4}){sub 3}]{sub 2} (6), respectively. The {sup 31}P NMR studies show that, in the presence of 1, the line width of the {sup 31}P resonance of L is temperature dependent, and at constant temperature, its broadening is proportional to the square root of the concentration of 1. This broadening is attributed to its exchange reaction with the mononuclear cobalt radical (CO){sub 3}LCo{sup {sm_bullet}} (3), which is generated by the homolysis of 1. Compound 1 catalyzes the hydroformylation of olefins in supercritical carbon dioxide. In contrast to the unsubstituted Co{sub 2}(CO){sub 8}, the phosphine-modified catalyst system is stable under low CO pressures and the hydroformylation reactions can be carried out at low pressures. In situ monitoring of {sup 31}P and {sup 59}Co NMR spectra of the solution shows that the phosphine-containing hydrido cobalt complexes 4 and 6 are the only hydrido cobalt complexes present in detectable concentrations in 1-catalyzed hydroformylation reactions; nevertheless, the possibility that the observed activity for 1 comes primarily from the more active HCo(CO){sub 4}, present in concentrations below detectable limits, has not been rigorously excluded.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 961431
• Report Number(s): ANL/CMT/JA-47705
• Journal Information: Organometallics, Journal Name: Organometallics Journal Issue: 11 ; May 24, 2004 Vol. 23; ISSN 0276-7333; ISSN ORGND7
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

08 HYDROGEN
ALKENES
CARBON DIOXIDE
CARBONYLATION
CARBONYLS
CATALYSTS
COBALT
COBALT COMPLEXES
HYDROGEN
HYDROGENATION
LIGANDS
LINE WIDTHS
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
PHOSPHINES
PRESSURE RANGE MEGA PA 10-100
RADICALS
RESONANCE
TEMPERATURE DEPENDENCE