The complexes [Cp*M(κ3N,N',N″-L)][SbF6] (Cp* = η5-C5Me5; M = Rh, 1, Ir, 2; HL = pyridinyl-amidine) display M/N transition metal frustrated Lewis pair reactivity toward a range of substrates containing triple bonds. Whereas the rhodium complex 1 reacts with CO yielding compound [Cp*Rh(CO)(κ2C,N-LCO)][SbF6] (3), which contains a terminal carbonyl and a carbamoyl group, the iridium complex 2 generates compound [Cp*Ir(κ3C,N,N'-LCO)][SbF6] (4), which only features the carbamoyl group. Compounds 1 and 2 react with stoichiometric amounts of the isocyanides CNR (R = Cyclohexyl, p-C6H4(OMe), CH2SO2(p-Tolyl)) to give the corresponding 1,1-insertion complexes [Cp*M(κ3C,N,N'-LCNR)][SbF6] (5-10). Complexes containing inserted and coordinated isocyanide ligands of formula [Cp*M(CNR)(κ2C,N-LCNR)][SbF6] (11-15) are obtained upon treating 1 and 2 with excess of the corresponding isocyanide. Compound 2 reacts with CNtBu affording the adduct [Cp*Ir(CNtBu)(κ2N,N'-L)][SbF6] (16) which contains a terminal CNtBu ligand. Complex 16 is protonated by HSbF6 to give [Cp*Ir(CNtBu)(κ2N,N'-HL)][SbF6]2 (17). The terminal alkynes HC≡CR (R = Ph, CO2Et) react with 1 and 2 rendering the alkynyl complexes 18-21. Dimethyl acetylenedicarboxylate reacts with complex 2 to give compound 22 via the formal 1,2-addition of a basic nitrogen atom and the metal across the alkyne triple bond. The new complexes have been characterized by analytical, spectroscopic and X-ray diffraction (XRD) methods.

The rhodium and iridium complexes [Cp*M(κ3N,N',N″-L)][SbF6] (Cp* = η5-C5Me5; M = Rh, 1; Ir, 2; HL = pyridinyl-amidine ligand) exhibit three different cooperative metal-ligand reactivity modes when interacting with nonfunctionalized ketones. With the methyl ketones CH3COR (R = CH3, Ph, CF3), activation of the ketone methyl C(sp3)-H bond yields ketonyl compounds of formula [Cp*M(CH2COR)(κ2N,N'-HL)][SbF6]. With the ketones (CF3)2CO and CF3COPh, the complexes add to the C═O double bond of the ketone. The addition of the iridium compound 2 occurs across the metal atom and the exocyclic carbon of the dearomatized pyridinyl moiety, and that of the rhodium analogue 1 takes place through the rhodium atom and the exocyclic methylene carbon of the Cp* ligand of the intermediate fulvene complex. In the rhodium case, the resulting metal-alkoxide derivative evolves to give rise to rhodium derivatives containing up to four added ketone molecules. In all of these processes, no additives are required, rendering them atom 100% efficient procedures for bond activation. From a mechanistic point of view, DFT calculation reveals that the diverse and selective behavior of 1 and 2 toward ketones can be explained by invoking three different intermediates, each driving the process through distinct reaction pathways.

The masked transition-metal frustrated Lewis pairs [Cp*M(kappa N-3,N',N''-L)][SbF6] (Cp*=eta 5-C5Me5; M=Ir, 1, Rh, 2; HL=pyridinyl-amidine ligand) reversibly activate H-2 under mild conditions rendering the hydrido derivatives [Cp*MH(kappa N-2,N'-HL)][SbF6] observed as a mixture of the E and Z isomers at the amidine C=N bond (M=Ir, 3Z, 3E; M=Rh, 4Z, 4E). DFT calculations indicate that the formation of the E isomers follows a Grotthuss type mechanism in the presence of water. A mixture of Rh(I) isomers of formula [(Cp*H)Rh(kappa 2N,N'-HL)][SbF6] (5 a-d) is obtained by reductive elimination of Cp*H from 4. The formation of 5 a-d was elucidated by means of DFT calculations. Finally, when 2 reacts with D-2, the Cp* and Cp*H ligands of the resulting rhodium complexes 4 and 5, respectively, are deuterated as a result of a reversible hydrogen abstraction from the Cp* ligand and D-2 activation at rhodium.

The dimers [(Cp*MCl)(2)(mu-Cl)(2)] (Cp* = eta(5)-C5Me5) react with N-pyridin-2-ylmethyl-N',N ''-bis-(2,6-diisopropylphenyl) guanidine (H2L) in the presence of NaSbF6, giving rise to chlorido compounds of formula [Cp*MCl(kappa N-2,N'-H2L)][SbF6] (M = Rh, 1; Ir, 2), in which the guanidine ligand adopts a kappa N-2,N' chelate coordination mode. Compounds 1 and 2 react with NaOH, rendering the complexes [Cp*M(kappa N-3,N',N ''-HL)][SbF6] (M = Rh, 3; Ir, 4), in which the HL ligand exhibits a fac kappa N-3,N',N '' coordination. Complexes 3 and 4 activate the H-H and O-H bonds of dihydrogen and water. The hydrido complex [Cp*IrH(kappa N-2,N'-H2L)][SbF6] (6) was isolated from the reaction of the iridium complex 4 with H-2. In the reaction of the rhodium complex 3 with D2O, its Cp* ligand is gradually and reversibly deuterated. A plausible mechanism for this H/D exchange is proposed. The new complexes have been characterized by analytical and spectroscopic means, including the determination of the crystal structures of the compounds 1-4 and 6 by X-ray diffractometric methods.

Reaction of the dimers [(Cp*MCl)2(μ-Cl)2] (Cp* = η5-C5Me5) with Ph2PCH2CH2NC(NH(p-Tolyl))2 (H2L) in the presence of NaSbF6 affords the chlorido complexes [Cp*MCl(κ2N,P-H2L)][SbF6] (M = Rh, 1; Ir, 2). Upon treatment with aqueous NaOH, solutions of 1 and 2 yield the corresponding complexes [Cp*M(κ3N,N',P-HL)][SbF6] (M = Rh, 3; Ir, 4) in which the ligand HL presents a fac κ3N,N',P coordination mode. Treatment of THF solutions of complexes 3 and 4 with hydrogen gas, at room temperature, results in the formation of the metal hydrido-complexes [Cp*MH(κ2N,P-H2L)][SbF6] (M = Rh, 5; Ir, 6) in which the N(p-Tolyl) group has been protonated. Complexes 3 and 4 react with deuterated water in a reversible fashion resulting in the gradual deuteration of the Cp* group. Heating at 383 K THF/H2O solutions of the complexes 3 and 4 affords the orthometalated complexes [Cp*M(κ3C,N,P-H2L-H)][SbF6] [M = Rh, 7; Ir, 8, H2L-H = Ph2PCH2CH2NC(NH(p-Tolyl))(NH(4-C6H3Me))], respectively. At 333 K, complexes 3 and 4 react in THF with methanol, primary alcohols, or 2-propanol giving the metal-hydrido complexes 5 and 6, respectively. The reaction involves the acceptorless dehydrogenation of the alcohols at a relatively low temperature, without the assistance of an external base. The new complexes have been characterized by the usual analytical and spectroscopic methods including the X-ray diffraction determination of the crystal structures of complexes 1-5, 7, and 8. Notably, the chlorido complexes 1 and 2 crystallize both as enantiopure conglomerates and as racemates. Reaction mechanisms are proposed based on stoichiometric reactions, nuclear magnetic resonance studies, and X-ray crystallography as well as density functional theory calculations.

[Cp*Rh(kappa N-3,N ',P-L)][SbF6] (Cp*=C5Me5), bearing a guanidine-derived phosphano ligand L, behaves as a "dormant" frustrated Lewis pair and activates H-2 and H2O in a reversible manner. When D2O is employed, a facile H/D exchange at the Cp* ring takes place through sequential C(sp(3))-H bond activation.

The reaction of the acetylacetonates [(η5-C5Me5)M(acac)Cl] with (SP)-[HMaxPhos][BF4] afforded cationic complexes with the formula (SM,RP)-[(η5-C5Me5)MCl(MaxPhos)][BF4] (M = Rh (1), Ir (2)). The reaction of (SP)-MaxPhos with [RuCl(μ-Cl)(η6-p-MeC6H4iPr)]2 and NH4X afforded (SRu,RP)-[(η6-p-MeC6H4iPr)RuCl(MaxPhos)][X] (X = BF4 (3), PF6 (3')). The complexes have been completely characterized by analytical and spectroscopic means, including the determination of the crystal structures of 1, 2 and 3'. Treatment of the iridium complex 2 with AgBF4, at 253 K, resulted in the intramolecular cyclometallation of one of the tert-butyl substituents of the MaxPhos diphosphane ligand, affording a mixture of isomers of (SIr,RP1,SP2 and RIr,RP1,RP2)-[(η5-C5Me5)Ir(MaxPhos)][BF4] (4a and 4b). However, rhodium complex 1 and ruthenium complex 3 reacted with AgBF4 forming the expected unsaturated intermediates "(ηn-ring)M(MaxPhos)" which were trapped by MeCN, affording the cationic adducts (SM,RP)-[(ηn-ring)M(MaxPhos)(MeCN)][BF4]2 (M = Rh (5), Ru (6)). Only one epimer at the metal was isolated in high yield for the complexes 1, 2, 3, 3', 5 and 6 and the metallation of 2 to give 4 occurs with high diastereoselectivity.

The synthesis and characterization of cationic iridium(III) aqua complexes of the formula [IrH(H2O)(PN*)(PP)][SbF6](2) (PN* = chiral phosphano oxazoline ligand; PP = diphosphane) as well as that of the OPOF2-containing complex [IrH(OPOF2)(PNiPr)(dppp)][SbF6] (10) are reported. The X-ray molecular structures of [IrH(H2O)(PNInd)(dppe)][SbF6](2) (1), [IrH(H2O)(PNInd)(dppen)][SbF6](2) (2), and 10a have been determined. Dichloromethane solutions of these aqua complexes efficiently catalyze the enantioselective 1,3-dipolar cycloaddition of the nitrone N-benzylidenephenylamine N-oxide to methacrolein and Diels-Alder reactions between cyclopentadiene and trans-beta-nitrostyrenes. In the first case, the catalytic reaction occurs with excellent endo selectivity and ee up to 85%; the Diels Alder reaction occurs rapidly at room temperature with good endo:exo selectivity and ee up to 90%. The dipolar cycloaddition intermediates [IrH(methacrolein)(PNInd)(PP)][SbF6](2) (PP = (S,S)-chiraphos (11), (R)-prophos (12)) have been characterized, and the molecular structure of 11 has been determined by an X-ray structural analysis.

Reaction of the dimer [Ir(mu-Cl)(eta(2)-coe)(2)](2) (coe = cyclooctene) with chiral phosphano oxazoline ligands (PN*) renders neutral mononuclear iridium(I) complexes of the formula [IrCl(eta(2)-coe)(PN*)] (1, 2), which in turn are oxidized to the corresponding iridium(III) hydride species [IrCl2H(eta(2)-coe)(PN*)] (3, 4) by treatment with aqueous HCl. The latter react with diphosphanes (PP) in the presence of NaSbF6 to afford cationic complexes of stoichiometry [IrClH(PN*)(PP)][SbF6] (5-16). The fluorophenyldiphosphane-containing compounds [IrClH(PN*)(dfpPe)][SbF6] (15, 16) evolve to the corresponding Ir(I) species [Ir(PN*)(dfppe)][SbF6] (17, 18) by HCl loss. The new compounds have been fully characterized by analytical and spectroscopic means, including the molecular structure determination of [IrCl2H (eta(2)-coe) (PNInd)] (3), [IrClH(PNInd)(dppen)] [SbF6] (6a,b), [IrClH(PNInd)(dppp)] [SbF6] (7a), [IrClH (PNiPr)-(dppP)][SbF6] (13a), [IrClH(pNInd)(dfppe)][SbF6] (is), [Ir(PNInd)(dfppe)][SbF6] (17), and [Ir(PNiPr)(dfpPe)] [SbF6] (18) by X-ray diffractometric methods.

The synthesis and characterization of optically active amino carboxylate complexes of formula [(η6-arene)Ru(Aa)Cl] (arene = C6H6, C6Me6, Aa = amino carboxylate) as well as those of the related trimers [{(η6-arene)Ru(Aa)}3][BF4]3 are reported. Trimerization takes place with chiral self-recognition: only diastereomers equally configured at the metal, RRuRRuRRu or SRuSRuSRu, are detected. The crystal structures of the complexes [(η6-C6H6)Ru(Pip)Cl] and [{(η6-C6Me6)Ru(Pro)}3][BF4]3 have been determined by X-ray diffraction methods. Both types of complexes catalyse the hydrogen transfer reaction from 2-propanol to ketones with moderate enantioselectivity (up to 68% ee). The enantiodifferentiation achieved can be accounted for by assuming that Noyori's bifunctional mechanism is operating.

s4 coordinate, from which one can get the structural change and reaction speed as a function of time.Forces on atoms can be related to ( ) t , r ρ via Hellmann-Feynman forces.Indeed it is also necessary to relate the behaviour of an isolated set of molecules to the real situation occurring in a chemical process.We feel essential to focus attention onto the key properties of ( ) t , r ρ , that is the leading link between most aspects of a non stationary system, from microscopic or macroscopic experimental side, or from a theoretical viewpoint.The acquired experience concerning diversified systems in a steady state should help in finding original and simple models for time evolving systems, a fascinating challenge for the near future.

Ruthenium complexes of formula [(eta(6)-arene)Ru(LL*)-(H2O)][SbF6](2) (arene = C6H6, p-MeC(6)H(4)iPr, C6Me6; LL* = bi-dentate chelate chiral ligand with PN, PP or NN donor atoms) have been tested as catalyst precursors for the asymmetric 1,3-dipolar cycloaddition of nitrones to methacrolein. The reaction occurs quantitatively with perfect endo selectivity and moderate enantioselectivity (up to 74% ee). The ruthenium aqua complexes can be prepared from the corresponding chlorides, [(eta(6)-arene)RuCl(LL*)][SbF6]. Dipolarophile intermediates [(eta(6)-arene)Ru(PNiPr)(methacrolein)][SbF6](2) {PNiPr = (4S)-2-(2-diphenylphosphanylphenyl)-4-isopropyl-1,3-oxazoline} as well as nitrone-containing complexes [(p-Me-C(6)H(4)iPr)Ru(PNiPr)(nitrone)][SbF6](2) (nitrone = N-benzylidenephenylamine N-oxide, N-benzylidenemethylamine N-oxide, 3,4-dihydroisoquinoline N-oxide) have been also isolated and characterised. The crystal structures of the chlorides (R-RU)-[(eta(6)-C6Me6)RuCl(PNiPr)][SbF6], (R-Ru)-[(eta(C6H6)-C-6)RuCl(PNInd)][SbF6] {PNInd = (3aR,8aS)-2-[2-(diphenyIphosphanyl)phenyl]-3a,8a-dihydroindanell[1,2-d]oxazole} and those of the aqua solvates (R-RU)-[(eta(6)-arene)Ru(PNiPr)(H2O)][SbF6](2) (arene = C6H6, C6Me6) were determined by Xray diffraction methods. (c) Wiley-VCH Verlag GmbH & Co.

AbstractThe cover picture shows the structure of a chiral half‐sandwich ruthenium(II) complex with the (4S)‐2‐[2‐(diphenylphosphanyl)phenyl]‐4‐isopropyl‐1,3‐oxazoline ligand that catalyzes the asymmetric 1,3‐dipolar cycloaddition reaction of nitrones with methacrolein. Catalyst precursors as well as dipolarophile or nitrone‐containing intermediates have been isolated and spectroscopically and/or crystallographically characterized. Details are discussed in the article by D. Carmona, M. P. Lamata, L. A. Oro et al. on p. 3155 ff.

Half-sandwich complexes of formula [(eta"-ring)MC1L]PF6 [L=(S)-2-[(S-p)-2-(diphenylphosphino)ferrocenyl]-4-isopropyloxazoline; (eta"-ring)M=(eta(5)-C5Me5)Rh; (eta(5)-C5Me5)lr; (eta(6)-p-MeC(6)H(4)iPr)Ru; (eta(6)-p-MeC(6)H(4)iPr)Os] have been prepared and spectroscopically characterised. The molecular structures of the rhodium and iridium compounds have been determined by X-ray crystallography. The related solvate complexes [(eta(5)-C5Me5)ML(Me2CO)](2+) (M=Rh, Ir) are active catalysts for the Diels-Alder reaction between methacrolein and cyclopentadiene. (c) 2006 Elsevier B.V. All rights reserved.

AbstractThe cover picture shows the structure of a new chiral iridium(I) complex with the (4S)‐2‐[2‐(diphenylphosphanyl)phenyl]‐4‐isopropyl‐1,3‐oxazoline ligand [(S)‐PN] that catalyses the asymmetric Michael addition of keto or cyano esters to α,β‐unsaturated carbonyl compounds. The hydrido(enolato) species, [IrH(NCCHCO2R2){(S)‐PN}2]Cl, postulated as catalytic intermediates, have also been isolated and spectroscopically characterised. Details are discussed in the article by D. Carmona et al. on p. 1657 ff.

The chiral iridium compounds [IrCl(COE){(S)-PN)] {COE = cyclooctene, PN = (4S)-2-[2-(diphenylphosphanyl)phenyl]-4-isopropyl-1,3-oxazoline, (1)), [Ir(acac)CIH((S)-PN)] (Hacac = acetylacetone, (2)} and [Ir{(S)-PN)(2)]A {A = Cl (3a,b); BF4 (4a,b); PF6 (5a,b)) have been prepared, characterised and employed as catalysts for the asymmetric Michael addition of keto or cyano esters to alpha,beta-unsaturated carbonyl compounds. The X-ray molecular structures of compounds 2 and 5b are reported. The model catalytic intermediates [IrH(NCCHCO2R){(S)-PN)(2)]Cl {R = Me (12), Et (13)} have also been isolated and characterised. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).

The iridium complex [Ir(mu-Cl)(PN)(PPh3)]2 (1) reacts with H2 affording only the kinetic isomer OC-6-55-C of the dihydride [IrClH2(PN)(PPh3)] (2) and with methanol yielding, also exclusively, the thermodynamic isomer OC-6-53-C (2b) of the same dihydride; complex 2b has been characterised by X-ray diffractometric methods.

The iridium complex [Ir(mu-Cl)(PN)(PPh3)](2) (1) reacts with H-2 affording only the kinetic isomer OC-6-55-C of the dihydride [IrClH2(PN)(PPh3)] (2) and with methanol yielding, also exclusively, the thermodynamic isomer OC-6-53-C (2b) of the same dihydride; complex 2b has been characterised by X-ray diffractometric methods.