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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.

New Catalysis Methodologies aimed to reduce toxicity for human health and environment[1] constitute a recognized target for Sustainable Chemistry. Our studies concern new ligands design and development by using non-injurious solvents, moderate conditions and no waste products. Currently our group is involved on the synthesis and characterization of new water soluble polydentate cyclopentadienyl derivatives, tethering from 1 to 3 alcoholic pendants NaCpO,O,O = Na[C5H5-nRn] [n=1,2,3 R = CH(CH2)3CHOH]. Substitution reaction is performed either by one or multistep protocol. Recycle leads to complete conversion. The reaction discriminates by impeded rotation (atropisomerism) either position (1,2,4) or central chirality sequence, shown by the cycloalkyl stereocentres. Reaction products result only two among all the possible isomers. Rhodium coordination of OH-tethered triply functionalized Cyclopentadienyl ligands stereospecifically selects the less congested enantioface, affording a unique planar chiral stereoisomer (pS or M) (LL)Rh{C5H2[CH(CH2)3CHOH]3} (LL = CO, COD, CH2CH2, NBD), whose nature was determined by different spectroscopic means (ESI-Ms, UV, CD, IR). X-ray diffraction studies in the case of [(NBD)RhCpO,O,O] identifies one of the two diasteroisomer as [1(R,S), 2(S,R), 4(S,R)]C5H2[C*H(CH2)3CHOH]3}, confirming the suggested structure in solution performed by n.O.e. and bidimensional NMR experiments. The latter complex shows high solubility (Ko/w=0.86) and high stability in water (over one week). Further coordination abilities of alcoholic pendants towards Titanium affording poly-alkoxy aggregate systems have also been explored. Preliminary investigations on the new class of hydrophilic Rhodium complexes as mediator for transfer hydrogenation of carboxyl olefins will be also reported. [1] (a) Cornils, B.; Herrmann, W.A.; Aqueous-Phase Organ ometallic Catalysis Wiley-VCH ed. 2002. (b) Cornils B; Herrmann.A. Multiphase Homogenous Catalysis Wiley-VCH ed. 2005.

New Catalysis Methodologies aimed to reduce toxicity for human health and environment constitute a recognized target for Sustainable Chemistry (1). Our studies concern new ligands design and development by using non-injurious solvents, moderate conditions and no waste products. Currently our group is working on projects involving the synthesis and characterization of new water soluble polydentate Cyclopentadienyl ligands, tethering 1-3 alcoholic pendants of the type CpO,O,O = [C5H5-nRn] (n=1,2,3 R = CH(CH2)3CHOH), obtained by one-pot reaction between NaCp and oxirane excess [CH(CH2)3CH]O (Scheme1). The reaction discriminates position and chirality sequence of the cycloalkyl substituents stereocentres {for example (S,R,S) for (1,2,4)-C5H2[C*H(CH2)3CHOH]3}. Coordination to transition metals stereospecifically selects less congested enantioface (pR), affording one unique stereoisomer. Coordinative pi greco-abilities give raise to Mn, Fe and Rh complexes. The nature of complexes has determined by different spectroscopic means (ESI-Ms, UV, ORD, CD, IR, bidimensional and n.O.e. NMR techniques). X-ray diffraction studies on examples of the class (LL)Rh{C5H2[CH(CH2)3CHOH]3} (LL = NBD,CO)(1) species confirm the suggested structure. The [NBDRhCpO,O,O] complexes show a peculiar solubility and high stability in ethanol or water. Currently, we are exploring further coordination abilities of alcoholic pendants towards Titanium centre, to obtain bimetallic complexes. Extension of the described synthetic protocol to test general applicability on further polyfunctionalized pi greco-ligands as Indenyl, Fluorenyl and Thienyl is also under investigation. These experiments are of support to investigate on discrete model the cooperativity exerted by metal of different nature (Rh, Ti) or acidic sites (Ti, OH) inside heterogeneous catalytic structures (zeolites, perowskites or mixed oxides) and to test grafting ability or alterations in the stereo-electronic requisites of immobilized Rh sites. We plan to get insight into hydrophilic Rhodium complexes as promising transfer hydrogenation (2) mediator or polymerization of oxygenated olefins in biphasic catalysis. 1 a Cornils, B.; Herrmann, W.A.; Aqueous-Phase Organ ometallic Catalysis Wiley-VCH ed. 2002. 1 b Cornils B; Herrmann.A. Multiphase Homogenous Catalysis Wiley-VCH ed. 2005. 2 Mebi, C.A.; Frost, B.J.; Organometallics 2005, 24, 2339.

È stato recentemente dimostrato che anioni Cp(C5H5)- (1) , Ind(C9H7)- e Flu(C13H9)- (2) promuovono l’ apertura di epossidi formando leganti sostituiti da una catena alchilica funzionalizzata all’ossigeno. In questo contesto viene descritta la sintesi di alcool ciclopentadienilici bi- e tri-sostituiti, del tipo Na[C5H5-nRn] (n=2,3 R = CH(CH2)3CHOH), ottenuti conducendo la reazione per sollecitazione termica in presenza di un eccesso di ossirano. È stato inoltre dimostrato che è possibile introdurre una seconda funzionalizzazione sull’anello indenilico [C9H6(CH(CH2)3CHOH)2]- e fluorenilico [C13H8(CH2CHMeOH)2]- le cui specie neutre, quale conferma dell’identita’ dell’anione, sono stati caratterizzate ai raggi X. Le capacità coordinative di questa classe di leganti pi greco polidentati, alcool ed etere sostituiti, sono state inoltre saggiate con metalli di transizione, al fine di studiare potenziali catalizzatori anfifilici bifasici, ottenendo i complessi half-sandwich (A, B e C), la cui natura e’ stata confermata attraverso tecniche spettroscopiche. (ESI-MS; IR; NMR) (1) Brookings D.C.; Harrison S.A.; Whitby R.J.; Crombie B.; Jones R.V.H.; Organomet., 2001; 20; 4574; Whitby R.J. PCT Int. Appl.; 2003;WO 2003013724 A1. (2) Cerini.S. 2004. Università di Bologna Ph.D dissertation .

We recently demonstrated that Cp, Ind and Flu anions cause epoxides ring opening reaction to form mono-functionalized O-bearing ligands. Now we describe the synthesis of polydentate derivatives, obtained by running the reaction in the presence of oxirane excess. In fact, under this condition the nucleophylic attack of cyclopentadienyl gives in one step mono [C5H4R; R = CH2CH(Me)OH or CH(CH2)3CHOH] (1) o bifunctionalized ligands [C5H3R2] (2), if thermally solicited.By analogy, the reactions with Indenyl anion affords 3 and the disubstituted derivative 4.The coordination abilities of the class of polydentate -ligands, alcohol or ether substituted, have been tested with transition metals to give half-sandwich (A or B)