Reactivity of iridium PCP pincer complexes toward CO and CO2• crystal structures of IrH(k2-O2COH){C6H3-2,6-(CH2PBut2)2} and IrH(C(O)OH){C6H3-2,6-(CH2PBut2)2}• H2O

The reactivity of a series of PCP pincer complexes with carbon monoxide and carbon dioxide has been studied. The reactions of CO2 with PCP pincer iridium complexes provide the 16-electron complex Ir(eta(2)-CO2){C6H3-2,6-(CH2PBu2t)(2)} (2). Analogously, reactions with CO yield the 16-electron monocarbonyl compound Ir(CO){C6H3-2,6-(CH2PBu2t)(2)} (4). When IrH(OH)-{C6H3-2,6-(CH2PBu2t)(2)} (1b) is reacted with CO2, the hydrido bicarbonate complex IrH(kappa(2)- O2COH){C6H3-2,6-(CH2PBu2t)(2)} (3) is obtained. Analogously, when IrH2{C6H3-2,6-(CH2PBu2t)(2)} (1a) is reacted first with CO2 and then with H2O, the reaction affords the same species (3). Thus, compound 3 can be obtained irrespective of the order of addition of the substrates CO2 and H2O to 1a. Similarly, the reaction of 1b with CO affords the insertion product IrH(C(O)OH){C6H3-2,6-(CH2PBu2t)(2)} (5). The identities of 3 and 5 have been confirmed by single-crystal X-ray structure determinations.