HCo(CO)₃-Catalyzed Propene Hydroformylation. Insight into Detailed Mechanism

Abstract

The entire catalytic cycle of propene hydroformylation using HCo(CO) 3 as an active catalyst has been systematically investigated at the B3LYP density functional level of theory. It is found that the most stable π-complex HCo(CO) 3 (η 2 -H 2 CdCHCH 3 ) has a CdC double bond coordination in the equatorial position, and the subsequent olefin insertion (alkylation) process is reversible, in agreement with the experimental finding. The hydride migratory insertion is accompanied by Co(CO) 3 pseudorotation, leading to the Co‚‚‚H-C agostic stabilized (iso)propyl complex (C 3 H 7 )Co(CO) 3 with the alkyl group at the axial position and thus does not take place on a C s symmetry potential energy surface. The regioselectivity is mainly determined by the relative stability of the alkyl cobalt tetracarbonyl complexes (C 3 H 7 )-Co(CO) 4 from the exothermic and irreversible CO addition to the alkyl cobalt tricarbonyl complexes (C 3 H 7 )Co(CO) 3 , which is therefore a thermodynamic controlled process. The CO insertion process (carbonylation) proceeds via two Co(CO) 3 pseudorotated transition states and a Co‚‚‚H-C agostic stabilized intermediate. The resulting most stable complex (C 3 H 7 -CO)Co(CO) 3 with the acyl group in the axial site has a η 2 -OdC interaction at the equatorial site, and the computed characteristic vibrational modes agree well with the available experimental data. In contrast to the generally accepted conclusion, H 2 coordination to the acyl complex rather than oxidative addition is the rate-determining step after HCo(CO) 3 generation. This finding is supported by the high stability of the acyl complex toward further H 2 addition, as found experimentally.

A DFT study of the mechanism of palladium-catalyzed alkoxycarbonylation and aminocarbonylation of alkynes: Hydride versus amine pathways

“…The negative direction modes of the above transition states (283i and 306i) indicate the right direction of carbonylation. The computed carbonylation barriers for both the trans (4CT/(4CT/5CT-TS)/5CT) and the gem routes (4CG/(4CG/ 5CG-TS)/5CG) are 5.9 and 8.2 kcal/mol, and they are close to those of corresponding step in propene hydroformylation [30]. Fig.…”

“…Therefore, two types of vinyl complexes, trans (T) and gem (G), can be formed. This alkylation reaction was considered as the key step for the regioselectivity [30].…”

“…The support of these mechanisms was based on the understanding of the influence of different reaction parameters on the catalytic activity and regioselectivity. The use of the theoretical calculations to model catalytic cycles has been reported for metalcatalyzed hydroformylation [13], hydrogenation [14], crosscoupling [15], and other reactions. However, reports on computational studies on the alkoxycarbonylation and aminocarbonylation Here, we present a computational study of the alkoxycarbonylation and aminocarbonylation of alkynes that were developed in parallel with experimental results [16].…”

Catalytic Markovnikov and anti‐Markovnikov Functionalization of Alkenes and Alkynes: Recent Developments and Trends

“…For example, the latest density functional theory (DFT) computation for hydroformylation, which involves the conversion of terminal olefins and syngas (H 2 + CO) directly to the corresponding linear and branched aldehydes, shows that the regioselectivity of the unmodified cobalt catalyst [CoH(CO) 4 ] is determined by the higher stability of the linear (primary) alkyl cobalt tetracarbonyl complex [CoR(CO) 4 ] with respect to the branched (secondary) isomer. [7] This difference in energy comes from the steric interaction between the alkyl group and the equatorial CO ligands. Neither the stability of the alkyl cobalt tricarbonyl complex [CoR(CO) 3 2 ], the situation becomes more complicated due to the equatorial-equatorial (eq-eq) and equatorialapical (eq-ax) isomers on the basis of the phosphane ligands.…”

Az ón(II)-halogenidek koordinációs kémiájának jelentősége a platinakatalizált hidroformilezési reakcióban

“…A fõbb elemi lépések megegyeznek, függetlenül attól, hogy a katalizátor kobalt, 14 ródium, 15 vagy platina 16 központi atomra épül (2. Ábra).…”