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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.

The introduction of hydroxyl groups into ligand is able to confer high hydrophilic features to be transferred to the related metal systems.[Budapest] The atom-economy synthetic procedure adopted consists in the Cp- oxide ring opening and results in one-step, quantitative and stereoselective formation of multi-hydroxyl rac-1,2,4- C5H2[CH(CH2)3CHOH]3 CpOOO ligand1. Rh complexation of CpOOO gives rise to a novel class of water-soluble (Kpo/w 0.86) complexes (L,L)RhCpOOO (LL=NBD 1, COD 2, CH2CH2 3, CO 4,) characterized by their spectroscopic features (ESI-Ms, IR, 2D, n.O.e. NMR). The X-ray diffraction studies on 1a reveal in the crystal structure the occurrence of one couple of enantiomeric pairs, whilst the crystal packing shows an interesting self-organization in macrocycles network, promoted by strong intermolecular hydroxyl H-bonding. This effect has been exploited, by performing VT NMR experiments in different donor solvents (CDCl3, py, DMSO). Unpredictably, in the absence of chiral tag, 1 exhibits solvent-dependent chiroptical properties (CD, aD25), which are correlated with UV transitions and DFT calculations. The intra/inter molecular H-binding reveals to be crucial to drive the equilibrium of the observed atropisomers 1a and 1b, by varying the planar chirality on the two p-complexes (1R,2S,4R)CpOOO(RhNBD) 1a and (1S,2R,4S)CpOOO(RhNBD) 1a’, differing for the stereogenic centres sequence. The different helicity (SP or RP)2 of the propeller-like CpOOO ligand controls the conformation of the rotamers, driving the equilibrium between 1a (SP) ═ 1b (RP). Thermal treatment causes complete transformation of 1b in 1a. The thermodinamically favourite SP configuration alters the racemic mixture to become scalemic, giving rise to a detectable enantiomeric excess.