Half-Sandwich cyclopentadienyl Iridium complexes bearing pendant oxygen ligands

The chemistry of cyclopentadienyl ligands with functionalized pendant arms is still largely studied [1]. Herein we describe the totally diastereoselective formation of new air stable and water soluble Iridium (I) (Ko/w 0.9) and (III) complexes, by utilizing the recently synthesized, [2] multi-substituted and overcrowded, propeller-like ligand CpOOO, rac-1,2,4[C5H2R3; R = CH(CH2)3CHOH]. The latter reacts with [Ir(COD)Cl]2 giving quantitatively [Ir(COD)CpOOO] 1. Iodide addition to dichloromethane solution of 1 causes prompt displacement of the coordinated olefin, yielding dinuclear Iridium(III) [Ir(η5-CpOOO)I(µ-I)]2 2, which has been isolated as a red powder [3]. In agreement with the proposed structure, 1H NMR spectra of species 2 exhibit high-shifted double set of signals for the Cp groups. Reactions of 2 with phosphines (PR3: R = Me, Ph) or pyrazole (C3H4N2) ligands form quantitatively Ir(η5-CpOOO)I2L (L = PR3, R = Me 3, Ph 4; pzH 5), by iodide bridge breaking. All the complexes, isolated as dark yellow solids, have been spectroscopically characterized. To get new insights on oxidative addition mechanism paths, [4] further reactivity of 1 with CH3I is currently under investigation.