4 Pincer Iridium Complexes
The term “pincer” refers to ligands that generally coordinate in a mer tridentate
configuration [158]. This tridentate coordination mode results in strong binding to
the metal centre and high stability for the metal-tridentate ligand unit. Additionally,
pincer ligands have a modular nature that allows for a high tunability of their
electronic and steric properties. Within the last two decades, the use of pincer
compounds for chemical transformations has increased greatly [158–161]. A number of reviews focusing on the catalytic applications of this type of complexes have
been published in the recent years [162–170]. In particular, some pincer iridium
complexes have been found to be effective for the TH of unsaturated substrates
[171–175]. Here, we summarise the progress in this area since 2015.
With only 0.1 mol% of the chiral P,N,N
0 -pincer catalyst 65a (Scheme 37), at
40
C, several aromatic ketones with electron-donating or electron-withdrawing
substituents in 2–3- and 4-positions (B1-B3, B5, B6, B8, B10-B12, B15, B18,
Scheme 37 Pincer iridium TH catalysts
108
M. Pilar Lamata et al.
The term “pincer” refers to ligands that generally coordinate in a mer tridentate
configuration [158]. This tridentate coordination mode results in strong binding to
the metal centre and high stability for the metal-tridentate ligand unit. Additionally,
pincer ligands have a modular nature that allows for a high tunability of their
electronic and steric properties. Within the last two decades, the use of pincer
compounds for chemical transformations has increased greatly [158–161]. A number of reviews focusing on the catalytic applications of this type of complexes have
been published in the recent years [162–170]. In particular, some pincer iridium
complexes have been found to be effective for the TH of unsaturated substrates
[171–175]. Here, we summarise the progress in this area since 2015.
With only 0.1 mol% of the chiral P,N,N
0 -pincer catalyst 65a (Scheme 37), at
40
C, several aromatic ketones with electron-donating or electron-withdrawing
substituents in 2–3- and 4-positions (B1-B3, B5, B6, B8, B10-B12, B15, B18,
Scheme 37 Pincer iridium TH catalysts
108
M. Pilar Lamata et al.