demonstrated activation of CO 2 by manganese pincer complexes using two different
modes of metal-ligand cooperation, amido/amino mode that performs [1,2]activation of CO 2 and aromatization/dearomatization mode that performs [1,3]activation of CO 2 (Scheme 6) [55]. A dearomatized manganese PNN* complex
3 reacts with CO 2 to form complex 4 where new C–C and Mn–O bonds are formed
and the pincer ligand becomes aromatized as observed for Ru [52], Re [53] and Fe
[54] (Scheme 5), whereas the Mn-amido complex 5 reacts with CO 2 to form
complex 6 where new Mn–O and N–C bonds are formed (Scheme 6). The latter is
b
Scheme 4 (continued)
Scheme 5 Common binding mode of CO 2 (left) and binding of CO 2 by metal-ligand cooperation
(right)
Scheme 6 Reactivity of CO 2 with manganese PNN complexes using metal-ligand cooperation via
aromatization/dearomatization mode (left) and via amido/carbamato mode (right)
6
A. Kumar and D. Milstein
modes of metal-ligand cooperation, amido/amino mode that performs [1,2]activation of CO 2 and aromatization/dearomatization mode that performs [1,3]activation of CO 2 (Scheme 6) [55]. A dearomatized manganese PNN* complex
3 reacts with CO 2 to form complex 4 where new C–C and Mn–O bonds are formed
and the pincer ligand becomes aromatized as observed for Ru [52], Re [53] and Fe
[54] (Scheme 5), whereas the Mn-amido complex 5 reacts with CO 2 to form
complex 6 where new Mn–O and N–C bonds are formed (Scheme 6). The latter is
b
Scheme 4 (continued)
Scheme 5 Common binding mode of CO 2 (left) and binding of CO 2 by metal-ligand cooperation
(right)
Scheme 6 Reactivity of CO 2 with manganese PNN complexes using metal-ligand cooperation via
aromatization/dearomatization mode (left) and via amido/carbamato mode (right)
6
A. Kumar and D. Milstein