Reactivity of Iridium PCP Pincer Complexes toward CO and CO2. Crystal Structures of IrH(κ2-O2COH){C6H3-2,6-(CH2PBut2)2} and IrH(C(O)OH){C6H3-2,6-(CH2PBut2)2}·H2O

Abstract

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(η2-CO2){C6H3-2,6-(CH2PBut2)2} (2). Analogously, reactions with CO yield the 16-electron monocarbonyl compound Ir(CO){C6H3-2,6-(CH2PBut2)2} (4). When IrH(OH){C6H3-2,6-(CH2PBut2)2} (1b) is reacted with CO2, the hydrido bicarbonate complex IrH(κ2-O2COH){C6H3-2,6-(CH2PBut2)2} (3) is obtained. Analogously, when IrH2{C6H3-2,6-(CH2PBut2)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-(CH2PBut2)2} (5). The identities of 3 and 5 have been confirmed by single-crystal X-ray structure determinations.