Reactivity of Iridium PCP Pincer Complexes toward CO and CO₂. Crystal Structures of IrH(κ²-O₂COH){C₆H₃-2,6-(CH₂PBu^t₂)₂} and IrH(C(O)OH){C₆H₃-2,6-(CH₂PBu^t₂)₂}·H₂O

Abstract

The reactivity of a series of PCP pincer complexes with carbon monoxide and carbon dioxide has been studied. The reactions of CO 2 with PCP pincer iridium complexes provide the 16electron complex Ir(η 2 -CO 2 ){C 6 H 3 -2,6-(CH 2 PBu t 2 ) 2 } (2). Analogously, reactions with CO yield the 16-electron monocarbonyl compound Ir(CO) is reacted first with CO 2 and then with H 2 O, the reaction affords the same species (3). Thus, compound 3 can be obtained irrespective of the order of addition of the substrates CO 2 and H 2 O to 1a. Similarly, the reaction of 1b with CO affords the insertion product IrH(C(O)OH){C 6 H 3 -2,6-(CH 2 PBu t 2 ) 2 } (5). The identities of 3 and 5 have been confirmed by single-crystal X-ray structure determinations.

Reversible Reactions of Ni and Pd Hydroxo Pincer Complexes [(iPrPCP)M–OH] with CO2: Solid‐State Study of the Decarboxylation of the Monomeric Bicarbonate Complexes [(iPrPCP)M–OCOOH] (M = Ni, Pd)

“…These associate in pairs through hydrogen bonds, as previously observed in the crystal structures of related bicarbonate complexes. [7][8][9] The molecular pairs occupy two types of crystallographic sites. One of them is located on a crystallographic inversion centre that relates the [( iPr PCP)M-OCOOH] halves within the pair, whereas in the second site both molecular fragments are crystallographically independent.…”

“…[6] In recent years, the reactions of related pincer-containing hydroxides of Ni and Pd with CO 2 have been investigated. [7][8][9][10][11] The primary products of these reactions are bicarbonate complexes arising from the formal insertion of CO 2 into the M-OH bond. Although bicarbonate complexes are in general rather elusive species, those containing pincer ligands are stable enough to allow isolation or, at least, unambiguous identification in solution.…”

Reactivity of Pincer Complexes Toward Carbon Monoxide

“…Thus, in 2004, Brookhart and coworkers synthesized [38], in an analogous manner as reported by Morales-Morales and Jensen [35] (Scheme 2.38), a series (p-XPCP)Ir(CO) derivatives (95a-f) to study the electronic effects of the p-substituents This complex readily reacts with CO (800 Torr) to afford compound (97) as a pale yellow solid in an almost quantitative yield (Scheme 2.44). The structure of this compound was unequivocally determined by the common spectroscopic techniques, including a single-crystal X-ray diffraction experiment.…”

“…(seeScheme2 35),. Milstein and coworkers synthesized the corresponding carbonyl derivatives (90) (Scheme 2.40)[36], finding, by comparing the absorption frequencies in infrared (1973 cm À1 for (76) versus 2005 cm À1 for (90)), that the electronic density is lower at the metal center in complex (90) (Scheme 2.41).…”

Synthesis, Structure, and Reactivity of Iridium(III) Complexes Containing a 4,6-Dimethyl-1,3-benzenediphenylimine Pincer Ligand

“…Iridium pincer complexes exhibit a wide range of reactivity, with applications which include electrocatalytic reduction of CO 2 , 15,16 C−H bond cleavage, 17−21 alkane metathesis, 22,23 and various dehydrogenation reactions. 8,24−37 The pincers used have typically been PCP 16,21,37 or POCOP 38,39 -type ligands.When occupying the central site of the tridentate pincer ligand, the M-C bond exhibits excellent thermal stability.Changing to nitrogen donors from phosphorus donors may increase ligand stability under oxidative conditions. Bis(imino)-aryl pincer metal complexes have increased in popularity over the past decade.…”