5 Mechanistic Insight into the Hydrogen Activation by Frustrated Lewis Pairs
189
O
B
C
6 F
5
C
6 F
5
C
6 F
5
H
H
SM
SM
O
B
C
6 F
5
C
6 F
5
C
6 F
5
H
H
+
SM
SM
H (-)
B
C
6 F
5
C
6 F
5
C
6 F
5
O
H
H
H
SM
SM
SM
H (-)
B
C
6 F
5
C
6 F
5
C
6 F
5
O
H
H
H
SM
SM
O=CMe
2
-6.81
O
H
H
SM
SM
H (-)
H (+)
B
C
6 F
5
C
6 F
5
C
6 F
5
Fig. 5.5
The calculated free energy profile for the wet-ether FLP-mechanism of carbonyl hydrogenation (see also Scheme 5.8) with water as the main active
Lewis base (LB) instead of the ether. The TS HH
and TS HT
are the transition states of the heterolytic H
2 activation and the hydride transfer to the protonactivated C(carbonyl), respectively. The zero-energy reference is the sum of the free reactant molecules; “Product” denotes the product complex including the
non-coordinated BCF and the alcohol with the alcohol …
water …
ethers hydrogen-bonds; “SM” stands for “solvent molecule” (ether). All relative free energies
are in kcal mol −1