Neopentyl-substituted PNP-pincer Ligand: Complexation with Iridium to Form an Iridacycle via Alkyl C–H Activation

Abstract

A new PNP-pincer ligand 1 bearing neopentyl substituents reacted with [Ir(cod)2]BF4 to form hydridoiridacycle 3 via oxidative addition of a C–H bond of a neopentyl group to IrI. Addition of π-acceptor ligands induced C–H reductive elimination to form cationic iridium(I) complexes 5 ligated by the π-acceptor ligand. Although 3 did not give a benzene adduct, reaction of 3 with nitrobenzene or acetophenone afforded the C–H activated 7a or 8a.

[Cp′FeI]2 as convenient entry into iron-modified pincer complexes: bimetallic η6,κ1-POCOP-pincer iron iridium compounds

“…Therefore, the u-geometry is usually favored in pincer-like complexes, but recently a few examples with the unusual ip-geometry have been reported. [53][54][55] Complex [7] + is slightly less sterically congested compared to [5] + -endo. VT 1 H NMR studies revealed a reduced Cp 0 -rotation barrier of DG z (200 K) = 8.9 kcal mol À1 .…”

A catalytic synthesis of dialkylamines from alkylamines using neopentyl-substituted PNP pincer–iridium complex

“…One can expect that the narrow space around the metal center due to the bulky substituents may suppress the reactivities of metal-hydrogen and metal-X bonds (X = C, N, and O). Therefore, we recently have reported design and synthesis of neopentyl-substituted PNP-pincer ligand 1 possessing remote steric bulkiness far away from the metal center [34]. Complexation of 1 with iridium complex afforded an iridacycle 2 with a cleavage of neopentyl C-H bond (Eq.…”

Pyridyl Phosphine Complexes in the Design of Hydration Catalysts

“…Substituents on such ligands span a wide range of electronic and steric properties, from electron-withdrawing C 6 F 5 groups through to bulky and electron-donating neopentyl groups. 75,76 This work aimed to investigate the synthesis, properties, and catalytic activity of rhodium and iridium complexes bearing "cooperative" pincer ligands. The PCNCP framework * was selected due to the ability of the backbone to undergo dearomatisation when deprotonated at the methylene positions (see chapter one).…”

“…For example, when the neopentyl-substituted ligand t BuCH 2 PNP is reacted with [Ir(cod)(µ-Cl)] 2 , the chelating cod ligand is displaced and one of the t Bu groups is metallated (Figure 4.1-A). 76 In the case of Ph PNP, the cationic η 4 -cod complex is formed (Figure 4.1-B). This complex is able to hydrogenate imines.…”

“…have reported the sole example of an iridium PNP ethene complex. 76 This square planar 16 electron complex was generated by reductive elimination of a metallated neopentyl group (see Figure 4.1) in the presence of ethene and was characterised by NMR spectroscopy. Three ethene complexes have been reported with CF 3 PCP ligands.…”