Abstract
DFT calculations were employed to investigate the mechanism of formation and the interconversion of reduced-hapticity (η x-C 6H 6)Cr(CO) n complexes (n = 1-5, x = 1-6) on both singlet and triplet energy surfaces. A variety of functionals (mPW1k, B3LYP, B97-1, and BP86) and basis sets (SDD, SDB-cc-pVDZ, and LANL2DZ+P) were used. The same structures were consistently found for all functional/basis set combinations. The structures of the different singlet and triplet complexes and comparisons between their energies are described. On the basis of the structures and energies of the intermediates and the transition states found for singlet reduced-hapticity complexes, a mechanism for the decomposition of the (η 6-C 6H 6)Cr(CO) 3 complex to Cr(CO) 6 is suggested. This mechanism, which is closely related to the arene exchange reaction mechanism, involves the formation of (η 1-C 6H 6)Cr(CO) 4 and (η 2-C 6H 6)Cr(CO) 5 complexes as ring-slippage intermediates along the pathway for the complete replacement of the benzene ring by carbonyl ligands. The barriers found for the ring-slippage process are accessible under mild conditions. Triplet reduced-hapticity complexes have different structures; however, they are similar in energy to the analogous singlet complexes. Formation of triplet reduced-hapticity complexes might take place in reactions of (η 6-C 6H 6)Cr(CO) 3 initiated by photolysis, which have been reported to show no observable decomposition to Cr(CO) 6.
| Original language | English |
|---|---|
| Pages (from-to) | 2315-2325 |
| Number of pages | 11 |
| Journal | Organometallics |
| Volume | 23 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - May 10 2004 |
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ASJC Scopus subject areas
- Inorganic Chemistry
- Organic Chemistry
Cite this
Arene hapticity in (C 6H 6)Cr(CO) n (n = 1-5) complexes : A DFT study of singlet and triplet energy surfaces. / Cohen, Revital; Weitz, Eric; Martin, Jan M L; Ratner, Mark A.
In: Organometallics, Vol. 23, No. 10, 10.05.2004, p. 2315-2325.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Arene hapticity in (C 6H 6)Cr(CO) n (n = 1-5) complexes
T2 - A DFT study of singlet and triplet energy surfaces
AU - Cohen, Revital
AU - Weitz, Eric
AU - Martin, Jan M L
AU - Ratner, Mark A
PY - 2004/5/10
Y1 - 2004/5/10
N2 - DFT calculations were employed to investigate the mechanism of formation and the interconversion of reduced-hapticity (η x-C 6H 6)Cr(CO) n complexes (n = 1-5, x = 1-6) on both singlet and triplet energy surfaces. A variety of functionals (mPW1k, B3LYP, B97-1, and BP86) and basis sets (SDD, SDB-cc-pVDZ, and LANL2DZ+P) were used. The same structures were consistently found for all functional/basis set combinations. The structures of the different singlet and triplet complexes and comparisons between their energies are described. On the basis of the structures and energies of the intermediates and the transition states found for singlet reduced-hapticity complexes, a mechanism for the decomposition of the (η 6-C 6H 6)Cr(CO) 3 complex to Cr(CO) 6 is suggested. This mechanism, which is closely related to the arene exchange reaction mechanism, involves the formation of (η 1-C 6H 6)Cr(CO) 4 and (η 2-C 6H 6)Cr(CO) 5 complexes as ring-slippage intermediates along the pathway for the complete replacement of the benzene ring by carbonyl ligands. The barriers found for the ring-slippage process are accessible under mild conditions. Triplet reduced-hapticity complexes have different structures; however, they are similar in energy to the analogous singlet complexes. Formation of triplet reduced-hapticity complexes might take place in reactions of (η 6-C 6H 6)Cr(CO) 3 initiated by photolysis, which have been reported to show no observable decomposition to Cr(CO) 6.
AB - DFT calculations were employed to investigate the mechanism of formation and the interconversion of reduced-hapticity (η x-C 6H 6)Cr(CO) n complexes (n = 1-5, x = 1-6) on both singlet and triplet energy surfaces. A variety of functionals (mPW1k, B3LYP, B97-1, and BP86) and basis sets (SDD, SDB-cc-pVDZ, and LANL2DZ+P) were used. The same structures were consistently found for all functional/basis set combinations. The structures of the different singlet and triplet complexes and comparisons between their energies are described. On the basis of the structures and energies of the intermediates and the transition states found for singlet reduced-hapticity complexes, a mechanism for the decomposition of the (η 6-C 6H 6)Cr(CO) 3 complex to Cr(CO) 6 is suggested. This mechanism, which is closely related to the arene exchange reaction mechanism, involves the formation of (η 1-C 6H 6)Cr(CO) 4 and (η 2-C 6H 6)Cr(CO) 5 complexes as ring-slippage intermediates along the pathway for the complete replacement of the benzene ring by carbonyl ligands. The barriers found for the ring-slippage process are accessible under mild conditions. Triplet reduced-hapticity complexes have different structures; however, they are similar in energy to the analogous singlet complexes. Formation of triplet reduced-hapticity complexes might take place in reactions of (η 6-C 6H 6)Cr(CO) 3 initiated by photolysis, which have been reported to show no observable decomposition to Cr(CO) 6.
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U2 - 10.1021/om034367z
DO - 10.1021/om034367z
M3 - Article
VL - 23
SP - 2315
EP - 2325
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 10
ER -