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Two neutral cyclometalated rhodium and iridium coordination assemblies [(F2ppy)

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International audience; A series of chiral cyclometalated iridium complexes of the type [Ir(C boolean AND N)(2)(C boolean AND C:)], {(C boolean AND N) = ppy (2); dfppy (3)} featuring a naphthalimide N-heterocyclic carbene ligand (C boolean AND C:) = (Naphthalimide-NHC) are described and fully characterized. The racemic complexes rac-2 and rac-3 were resolved via chiral column chromatography techniques into their corresponding enantiopure species Delta-2, Lambda-2, Delta-3, Lambda-3 as confirmed by their CD curves. This unique class of molecules containing organic and inorganic chromophores might be used as a platform to probe the stereochemical effect on the photophysical properties. Vibrational circular dichroism (VCD) was used as an important tool to assign successfully the stereochemistry of the enantiomers. TD-DFT calculations are also advanced to support the experimental studies and to rationalize the observed results.

International audience; Neutral cyclometallated Pt(II) complexes [(CNt-BuNt-Bu)Pt-R] (4-5) containing a bis-urea alkynyl (R) ligand have been prepared and fully characterized. The dichotomous nature of 4-5 makes it difficult to anticipate which interactions (hydrogen bonds, pi-pi stacking and Pt...Pt) will dominate their assembly process. The aggregation properties of 4-5 were thus probed by multifarious analytical (UV/Vis, FT-IR, NMR, MS, CD, emission) and computational (DFT, TD-DFT) techniques. CD analyses of sergeants-and-soldiers type mixtures between 4 and an enantiopure Pt-free monomer (S,S)-3 reveal that no amplification of supramolecular helicity occurs in this system. In fact, complex 4 acts as competitor or chain capper, likely through hydrogen bonding, of the homochiral assemblies formed by (S,S)-3. In DMSO, H-1 NMR and DOSY analyses indicate that 4 and 5 form aggregates. Likewise, the aggregation is promoted by the addition of H2O as suggested by red shift of the lowest energy emission band, which might originate from a (MMLCT)-M-3 excited state. TD-DFT calculations confirm that self-aggregation occurs through Pt...Pt and pi-pi interactions yielding head-to-tail aggregates in DMSO and DMSO/H2O mixtures. Our study therefore suggests a (condition dependent) competitive rather than a cooperative mode of action of the different types of interactions present in aggregates of 4-5.

Two coordination polymers of coinage metals with a rare pyridinium-betainoid L assembling ligand are reported. These polymers are obtained by self-assembly of the linker L and copper(I) or silver(I) ions in acetonitrile. The compounds were characterized by spectroscopic methods and by elemental analysis. The solid-state structures were unambiguously confirmed by single crystal diffraction studies. These assemblies exhibit original helicoidal arrangements. The UV-Vis. absorption and photoluminescence properties are reported as well.

International audience; A unique class of enantiopure N-heterocyclic carbene half-sandwich iridium complexes is reported. These compounds display stable configurations at the metal center, as demonstrated by their chiroptical properties. Remarkably, because of the nature of the naphthalimide molecule, two regioisomers containing five-membered [(R)-2a and (S)-2a] and six-membered [(R)-2b and (S)-2b] iridacycles were obtained. Density functional theory calculations are advanced to rationalize their relative stability.

International audience; Optically active halogenated arenes containing stereogenic benzylic alcohol reacts with [CpRu(CH3CN)3][PF6] to give the major diastereomer with 90% de, in which the metal center is preferentially placed on one face of the arene ring. Thus starting with (S)-1-(2-chlorophenyl)ethanol the metal complex (pS, S)-[CpRu(HO(CH3)CH-C6H4-Cl)][PF6] (pS, S)-1 was obtained in good yield, while the (R)-alcohol provided (pR, R)-[CpRu(HO(CH3)CH-C6H4-Cl)][PF6] (pR, R)-1 metal complex. These compounds display planar and central chiralities. For comparison purposes the analogous racemic compound (rac)-[CpRu(HO(CH3)CH-C6H4-Cl)][PF6] (rac)-1 was also prepared in good yield as well. Subsequent treatment of enantiopure and racemic complexes 1 with NaSH in THF allows halogen displacement to occur at room temperature and generates the related enantiopure neutral metallothioligands of the type (pS, S)-[CpRu(HO(CH3)CH-C6H4-S)], (pS, S)-2, (pR, R)-[CpRu(HO(CH3)CH-C6H4-S)] (pR, R)-2, and (rac)-[CpRu(HO(CH3)CH-C6H4-S)] (rac)-2 (S = sulfur). These metallothioligands react rapidly with [(MeCN)Pt(terpy)][OTf]2 building blocks to give the chiral coordination assemblies [Pt(terpy)-(pS,S)-2][OTf]2 (pS,S)-3, [Pt(terpy)-(pR,R)-3][OTf]2 (pR,R)-3 and the related racemic complex (rac)-3 in which the metal-chromophore is now placed in a chiral environment. The molecular structures of (rac)-3 and the enantiopure heterobimetallic complex (pR,R)-3 were determined and show different arrangements at the supramolecular level depending on whether a homochiral or heterochiral assembly is obtained. The induced circular dichroism curves for the right-handed (pR,R)-3 and left-handed (pS,S)-3 bimetallic complexes displayed mirror image Cotton bands, confirming the enantiomeric relationship between both compounds. Our method provides an entry to the preparation of a wide range of optically pure coordination compounds with potentially important properties.

Chiral two bladed complexes of [Co(L)2][BF4]2 (1) and [Zn(L)2][BF4]2 (2) containing an atropoisomeric semi-rigid bidentate ligand L were synthesized and characterized. They are obtained as homochiral species but in a racemic mixture via a ligand self-sorting mechanism. These enantiomers can be differentiated in solution using optically active anions.

International audience; 1,6-Allenynes are useful mechanistic probes in noble metal catalysis, since they can give rise to very distinct products in a highly selective fashion. Various cycloisomerization reactions have been described, and discrete mechanisms have been postulated. Of particular interest, whereas Alder-ene types of products can be obtained in a variety of ways using noble-metal catalysts (Au, Pt, Rh, hydrindienes have been reported solely with gold and platinum under specific conditions. It was shown in a previous study that this intriguing transformation required the presence of chloride ligands at the active catalytic species. Herein, the factors governing the fate of 1,6-allenynes under cycloisomerization conditions have been studied more thoroughly, revealing a much more complex scenario. The nature of ligands, counterions, and metals was examined, showing that hydrindienes can be isolated in the absence of halides, using electron-rich, bulky triorganophosphines or carbene ligands. This crucial finding could also be used to access hydrindienes in high yields, not only with gold or platinum but also with silver. On the basis of mass spectrometry, NMR spectroscopy, and computations, refined mechanistic scenarios have been put forward, also rationalizing counterion effects. Notably, a metal vinylidene intermediate has been proposed for the formation of the hydrindiene derivatives. Finally, in the presence of tris((triphenylphosphine)gold)oxonium tetrafluoroborate as catalyst, a new pathway has been unveiled, involving gold alkyne cr,it complexes and leading to previously unobserved [2 + 2] cycloaddition compounds.

Two cycloplatinated complexes of the form [Pt(NC)CH3(P)]+ incorporating a rare, bidentate NC-chelating pyridylpyridylidene ligand are reported. The phosphorus-based ligand P is either 2,4,6-triphenylphosphinine or triphenylphosphine. These mononuclear complexes have been fully characterised in solution and by single-crystal X-ray diffraction analysis. UV/Vis absorption and photoluminescence spectroscopy studies reveal strong phosphorescence from the phosphinine compound at 77 K but no emission from its triphenylphosphine analogue. This contrasting behaviour can be traced to the π-acceptor ability of the phosphabenzene ring, as corroborated by electrochemical and time-dependent DFT (TD-DFT) calculations.

A series of cyclometalated N-heterocyclic carbene complexes of the general formula [Ir(CN)(2)(CC:)] has been prepared. Two sets of compounds were designed, those where (CC:) represents a bidentate naphthalimide-substituted imidazolylidene ligand and (CN) = ppy (3a), F2ppy (4a), bzq (5a) and those where (CC:) represents a naphthalimide-substituted benzimidazolylidene ligand and (CN) = ppy (3b), F2ppy (4b), bzq (5b). The naphthalimide-imidazole and naphthalimide-benzimidazole ligands 1a,b and the related imidazolium and benzimidazolium salts 2a, b were also prepared and fully characterized. The N-heterocyclic carbene Ir(III) complexes have been characterized by NMR spectroscopy, cyclic voltammetry and elemental analysis. Moreover, the molecular structures of one imidazolium salt and four Ir(III) complexes were determined by single-crystal X-ray diffraction. The structures provide us with valuable information, most notably the orientation of the naphthalimide chromophore with respect to the N-heterocyclic carbene moiety. All compounds are luminescent at room temperature and in a frozen solvent at 77 K, exhibiting a broad emission band that extends beyond 700 nm. The presence of the naphthalimide moiety changes the character of the lowest excited state from (MLCT)-M-3 to (LC)-L-3, as corroborated by DFT and TD-DFT calculations. Remarkably, replacing imidazole with a benzimidazole unit improves the quantum yields of these compounds by decreasing the k(nr) values which is an important feature for optimized emission performance. These studies provide valuable insights about a novel class of N-heterocyclic carbene-based luminescent complexes containing organic chromophores and affording metal complexes emitting across the red-NIR range.

International audience; A new family of cationic dinuclear cyclometalated Pt(II) complexes containing an organometallic assembling ligand has been reported. The general formulas for these compounds is as follow: [R-(N∧C∧N)Pt—L-L—Pt(N∧C∧N)-R][X]2, where L-L = [Cp*Ir-p-(η4-C6H4S2)], R = H, X = OTf (5); R= CF3–, X = OTf (6a), SbF6 (6b); L-L = [Cp*Ir-p-(η4-C6H4Se2)] R= CF3–, X = OTf (7a), SbF6 (7b). In these coordination assemblies two cyclometalated R-(N∧C∧N)Pt moieties are held by either η4-dithio-p-benzoquinone complex [Cp*Ir-p-(η4-C6H4S2)] (3) or η4-diseleno-p-benzoquinone complex [Cp*Ir-p-(η4-C6H4Se2)] (4). The molecular structures of the known complex [4-CF3-(N∧C∧N)PtCl] as well as two compounds of the above family [(N∧C∧N)Pt–Cp*Ir-p-(η4-C6H4S2)—Pt(N∧C∧N)][CF3SO3]2 (5) and [CF3-(N∧C∧N)Pt—Cp*Ir-p-(η4-C6H4S2)—Pt(N∧C∧N)-CF3][CF3SO3]2 (6a) were ascertained by single crystal X-ray diffraction study and confirmed the formation of the target molecules. The solid-state packing of 5 and 6a confirms the presence π–π and short Pt···Pt interactions among individual units providing 1D supramolecular chains. To our knowledge, these are the only known examples where two cyclometalated Pt(N∧C∧N) units are assembled by a bridging ligand (vide infra). All compounds show phosphorescence in the bluish-green region (486–521 nm) in the solution at room temperature and exhibit higher luminescence quantum yields relative to the analogous compounds containing a Pt(terpy) chromophore in thin film.

A series of novel N-heterocyclic carbene coinage metal complexes containing a naphthalimide (NI) chromophore has been prepared and fully characterized. Two types of molecules are described those where the NI unit is directly attached to the carbene unit with the general formulae [(L1)–M–X], M = Cu, X = Cl (1a); M = Ag, X = I (1b) and M = Au, X = Cl, (1c). While in the second family, a π-extended carbene ligand precursor L2–H+I− (3) was prepared where the NI unit is distant from the imidazole unit via a phenyl-alkyne bridge. Only two N-heterocyclic carbene metal complexes were prepared [(L2)–M–Cl], M = Cu (2a) and M = Au (2c). The related silver carbene compound could not be isolated. The molecular structure of the carbene complex 1c was determined and confirmed the formation of the target compound. Interestingly, the structure shows the presence of an aurophilic interaction Au···Au at 3.407 Å between two individual molecules. The photophysical properties of the compounds were investigated in solution at room temperature. Preliminary results suggested that all compounds are luminescent and act as blue emitters (420–451 nm). These transition emissions can be attributed to the intraligand origin of the NI chromphore. Moreover, the carbene complexes featuring L2 ligand with π-extended system were found to be more luminescent.

Chiral two bladed complexes of [Co(L)

A new series of monoselenoquinone and diselenoquinone pcomplexes [(?6 p cymene)Ru(?4 C6R 4SeE)] (R=H E=Se (6); R=CH3 E=Se (7); R=H E=O (8)) as well as selenolate pcomplexes [(?6 p cymene) Ru(?5 C6H3R2Se)][SbF 6] (R=H (9); R=CH3 (10)) stabilized by arene ruthenium moieties were prepared in good yields through nucleophilic substitution reactions from dichlorinated arene and hydroxymonochlorinated arene ruthenium complexes [(?6 p cymene)Ru(C6R4XCl)] [SbF6]2 (R=H X=Cl (1); R=CH3 X=Cl (2); R=H X=OH (3)) as well as the monochlorinated pcomplexes [(?6 p cymene)Ru(?5 C6H3R2Cl)][SbF 6]2 (R=H (4); R=CH3 (5)). The X ray crystallographic structures of two of the compounds [(?6 p cymene)Ru(?4 C6Me4Se2)] (7) and [(?6 p cymene)Ru(?4 C6H 4SeO)] (8) were determined. The structures confirm the identity of the target compounds and ascertain the coordination mode of these unprecedented ruthenium pcomplexes of selenoquinones. Furthermore these new compounds display relevant cytotoxic properties towards human ovarian cancer cells. All in the family: A series of organometallic ruthenium complexes stabilize selenolate monoselenoquinone and diselenobenzoquinone entities through p bonding interactions to a (p cymene)RuII moiety (see figure). The complexes display moderate cytotoxic properties towards human ovarian cancer cells. © 2014 WILEY VCH Verlag GmbH Co. KGaA Weinheim.

A series of functionalized cyclometallated rhodium and iridium coordination assemblies 2-7 displaying a pi-bonded dioxolene ligand is described. The X-ray molecular structures of two of the above compounds showed the formation of a 1D supramolecular chain mediated by pi-pi interactions among individual units. The luminescent properties of these compounds are presented and discussed. These results show that the stacking interactions are retained also in solution and emission from excited dimeric species is observed.

We report the synthesis of a unique class of luminescent heterotrinuclear complexes of the general formulas [Pt(terpy)\Cp*Ir-p-(?4-C6H4Se2)\Pt(terpy)][X]4 (X = OTf, 3a; PF6, 3b; BF4, 3c; ClO4, 3d; BPh4, 3e). In these coordination assemblies two Pt(terpy) moieties are held by a stable ?4-diseleno-p-benzoquinone complex [Cp*Ir-p-(?4-C6H4Se2)]. The molecular structures of solvates of 3a and 3b were ascertained by single-crystal X-ray diffraction study and confirmed the formation of the target molecules. The solid-state packing of two of these complexes confirms the presence of π?π and Pt···Pt interactions among individual units providing a 1D supramolecular chain for 3a, while a dimer species is obtained for 3b, illustrating the effect of the counterion on directing the crystal packing of the individual molecules. All compounds show phosphorescence in the red region (685?705 nm) in fluid solution and in the solid state at room temperature, unlike the analogous compound Pt(terpy)\Cp*Ir-p-(?4-C6H4S2)\Pt(terpy)][CF3SO3]4 obtained with a dithiobenzoquinone organometallic linker, which is only luminescent at low temperature.

We describe the resolution of a planar chiral cationic iridium complex [Cp*Ir(\eta5-2-methyl-oxodienyl)][OT f] () following the counterion strategy, where anion metathesis by Δ-TRISPHAT generates the two diastereomers (pR, pS)-[Cp*Ir(\eta5-2-methyl-oxodienyl)][Δ-TRISPHAT] (, ). Upon fractional crystallization both compounds were separated as confirmed by 1H nuclear magnetic resonance (NMR) and circular dichroism studies recorded in solution. The latter represents the key-complex precursors for the enantioselective synthesis of metallated o-quinone methide complexes (, ). Chirality 25:449\textendash454, 2013. \textcopyright 2013 Wiley Periodicals, Inc.

A series of cyclometalated platinum(II) complexes of the type [(ppy)Pt(LM)]n+ (n = 0, 1) with ?-bonded catecholates acting as organometallic ligands (LM) have been prepared and characterized by analytical techniques. In addition, the structures of two complexes of the series were determined by single-crystal X-ray diffraction. The packing shows the formation of a 1D supramolecular assembly generated by dPt-?Cp* interactions among individual units. All complexes are luminescent in the solid state and in solution media. The results of photophysics have been rationalized by means of density functional theory (DFT) and time-dependent DFT investigations.A series of cyclometalated platinum(II) complexes of the type [(ppy)Pt(LM)]n+ (n = 0, 1) with ?-bonded catecholates acting as organometallic ligands (LM) have been prepared and characterized by analytical techniques. In addition, the structures of two complexes of the series were determined by single-crystal X-ray diffraction. The packing shows the formation of a 1D supramolecular assembly generated by dPt-?Cp* interactions among individual units. All complexes are luminescent in the solid state and in solution media. The results of photophysics have been rationalized by means of density functional theory (DFT) and time-dependent DFT investigations.

The synthesis of three deep-red-emitting iridium(III) complexes featuring a naphthalimide N-heterocyclic carbene ligand was investigated. The introduction of this organic chromophore onto the carbene moiety changed the character of the lowest excited state from triplet metal-to-ligand charge transfer to triplet ligand centered, as corroborated by time-dependent DFT calculations. All complexes displayed a naphthalimide- based deep-red phosphorescence emission above lambda = 630 nm in polymer matrix with good quantum yields (Phi approximate to 0.2) and long lifetimes.

International audience; no abstract

A novel class of chiral luminescent square-planar platinum complexes with a π-bonded chiral thioquinonoid ligand is described. Remarkably the presence of this chiral organometallic ligand controls the aggregation of this square planar luminophor and imposes a homo- or hetero-chiral arrangement at the supramolecular level, displaying non-covalent Pt–Pt and π–π interactions. Interestingly these complexes are highly luminescent in the crystalline state and their photophysical properties can be traced to their aggregation in the solid state. A TD-DFT calculation is obtained to rationalize this unique behavior.

The synthesis of a new family of coordination polymers [AgL2X]n (1a, X = CF3SO3; 1b, X = BF4; 1c, X = NO3; 1d, X = PF6) using 5-methoxy-1,3-bis(pyridin-3-ylethynyl)benzene (L2) as the self-assembling ligand is described. All compounds have been fully characterized by spectroscopic techniques and elemental analysis. In particular the X-ray molecular structures of 1a and 1b are reported and confirm the formation of 1D silver(I) chains. Their arrangements are described as a function and the nature of the anion. The supramolecular product 1a exhibits argentophilic Ag···Ag interactions to afford infinite double chains. Additionally, η1–AgI–π interactions lead to the formation of a network of stacked layers of double chains. In contrast, 1b lacks metal–counterion bonding and is constituted of infinite coordination polymers, which are held together by π–π interactions. The pivotal role of the counteranions on the overall packing arrangement of the polymers is presented and discussed.

(Pentamethylcyclopentadienyl)iridium di- I chloride dimer {[IrCp*Cl2]2}-catalyzed hydroalkoxylation of bis-homopropargylic alcohols provides an efficient access to dioxabicyclo[2.2.1]ketals. The cycloisomerizations proceed under mild conditions, with low catalytic loadings and short reaction times. This new protocol involving an Ir(III) catalyst also promoted the cycloisomerization of nitrogen-tethered 1,6-enynes to give azabicyclo[4.1.0]heptenes, enhancing the synthetic potential of our method.

Quinone methides (quinomethanes) act as important intermediatesin organic syntheses, as well as in chemical and biological processes.However, examples of such isolated species are scarce owing to theirhigh reactivity. Other important reactive intermediates are thio-and selenoquinones. However, unlike quinones, they are highly unstableand consequently do not exist in nature, hence their chemical andbiological properties remain unknown. In this account, we describethe first isolation of the above important reactive intermediates,by π-coordination to a (pentamethylcyclopentadienyl)iridium(Cp*Ir) moiety, and their X-ray molecular structures. Further,the reactivity of such trapped intermediates is reported. For instance,the metalated O-quinone methide underwent anunusual cycloaddition reaction compared with the free O-quinone methide, while the metalatedthioquinones were successfully used as organometallic linkers (OM-linkers)to construct luminescent coordination assemblies. The anticanceractivity of the selenoquinone metalated complex was studied, togetherwith related oxygen and sulfur analogues, and remarkably it wasshown to be the only cytotoxic compound with a comparable activityto cisplatin. 1 Introduction 2 Quinone Methides 2.1 First Isolation of Metal-Stabilized O-QuinoneMethides 2.1.1 Synthesis and Structural Characterization 2.1.2 Reactivity towards Electrophiles and Carbon-CarbonBond Formation 3 Thioquinones 3.1 First Isolation as Metal Complexes 3.1.1 Synthesis and Structural Characterization 3.1.2 Reactivity as Organometallic Linkers 4 Selenoquinones 4.1 Trapping Selenoquinones as Metal Complexes 4.1.1 Synthesis and Structural Characterization 4.1.2 Biological Properties 5 Concluding Remarks and Future Outlook

Caught in the act: The first stable η4-diseleno-p-benzoquinone complex, [Cp*lr(η4-C6H4Se2)], has been isolated. The X-ray structure confirms the coordination of the elusive diselenobenzoquinone intermediate. The anticancer activity of this complex was compared to related oxygen and sulfur analogs; only the diseleno complex was cytotoxic, having a comparable activity to cisplatin.

The chiral octahedral bimetallic assemblies [(bpy)(2)Ru(o-L(Ir))][CF(3)SO(3)](2) (2), [(ppy)(2)Rh(o-L(Ir))][NO(3)] (7) and [(ppy)(2)Ir(o-L(Ir))][NO(3)] (8) featuring chelating organometallic linker [Cp*Ir(η(4)-o-benzoquinone)] (o-L(Ir)) have been prepared and fully characterized. Anion metathesis following a convenient procedure allowed the preparation of the related diastereomers [Δ-(bpy)(2)Ru(o-L(Ir))][Δ-TRISPHAT](2) (2a) and [Λ-(bpy)(2)Ru(o-L(Ir))][Δ-TRISPHAT](2) (2b) as well as the octahedral rhodium [(Δ, Λ)-(ppy)(2)Rh(o-L(Ir))][Δ-TRISPHAT] (7a, 7b) and iridium [(Δ, Λ)-(ppy)(2)Ir(o-L(Ir))][Δ-TRISPHAT] (8a, 8b) bimetallic assemblies. (1)H NMR studies in solution carried out on these compounds showed different behavior. For instance, the rhodium and iridium compounds exhibited weak chiral recognition in contrast the ruthenium compounds allowed facile differentiation between the two diastereomers suggesting that chiral recognition occurs between the enantiopure anion and the cationic part of the molecule.

Electron-deficient arenes are now recognized as potent anion receptors, mainly through the establishment of π-anion interactions. Cyclopentadienyl ligands (Cp’s) also belong to the family of arenes that exhibit very low electron density at their centroid due to the presence of the metal on one side. As such, they also work as anion receptors. A closer look at the reported X-ray structures in which an anion is in short contact with the Cp framework reveals that in most cases the five-membered ring is substituted, generally pentamethylated (Cp*). This is quite surprising since Cp* is electron-richer than the unsubstituted Cp ligand. This computational study shows that Cp* functions as a ring bearing a gemstone: the anion establishes a strong π-interaction with the centroid, but this is not sufficient to hold it straight. For that matter, each methyl group develops a C−H···anion hydrogen bond, thus working as a claw to prevent the gem from falling. Although individually small, the interaction energy provided...

The organometallic assembly [Cp*Ir(η6-C6H2O4)(BF2)2(CF3SO3)][Cp*Ir(μ-Cl)3IrCp*] (3) was prepared from [Cp*Ir(solvent)3][OTf]2 (2) and 1,2,4,5 tetrahydroxybenzene (THB, 1) in acetone, in the presence of an excess amount of BF3·2H2O. Assembly 3 was fully characterized by multinuclear NMR spectroscopy. Remarkably, the X-ray molecular structure of 3 shows that an anion–π interaction occurs between the neutral component Cp*Ir(η6-C6H2O4)(BF2)2 of the assembly and the CF3SO3 anion of the cationic species [Cp*Ir(μ-Cl)3IrCp*]. Computational analysis was carried out on 3 to unravel the nature of this noncovalent interaction. Such an example could serve as a model to explain the important role of anions in organometallic chemistry and asymmetric catalysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

We report the first synthesis of π-bonded rhodio and iridio-o-benzoquinones [Cp*M(o-benzoquinone)] (M = Rh (3a); M = Ir (3b)) following a novel synthetic procedure. These compounds were fully characterized by spectroscopic methods; in particular the X-ray molecular structure of 3b was determined. Compounds 3a,b were used as chelating organometallic linkers for the design of a new family of chiral octahedral bimetallic complexes, 4−9. The X-ray molecular structure of [(bpy)2Ru(3b)][OTf]2 (5) is presented and shows that the organometallic linker 3b is chelating the ruthenium center. In particular, the carbocycle of the organometallic linker 3b adopts a η4-quinone form, where the Cp*Ir is also bonded to only four carbons. Further our strategy to design new assemblies with organometallic linkers is successfully achieved. These assemblies hold promise for new properties relative to those made from organic bidentate ligands.

Ein derzeit sehr aktives Forschungsgebiet befasst sich mit der Synthese und Anwendung von Koordinationsnetzwerken, die im Allgemeinen aus organischen Linkern und Ubergangsmetallen aufgebaut sind. Wir beschreiben hier eine neuartige Klasse von supramolekularen Strukturen mit metallorganischen Linkern in Form von Chinon- und Thiochinon-Komplexen der allgemeinen Formel [Cp*M(η4-Benzochinon)] (o- und p-Benzochinon, Cp*=C5Me5, M=Rh, Ir) und [Cp*Ir(η4-Thiobenzochinon)] (o- und p-Thiobenzochinon), die mit ihren freien O- bzw. S-Atomen an Metallionen wie CuI, AgI oder PtII binden und Koordinationsnetzwerke bilden. Hierbei fungieren die Chinon- oder Thiochinon-Komplexe als Geruste und die Metallzentren als Knotenpunkte. Eine Besonderheit dieser Strukturen sind die kurzen π-π- und M⋅⋅⋅M-Abstande, die zu nutzlichen photophysikalischen Eigenschaften fuhren. Mit den hier beschriebenen Bausteinen ist eine Vielzahl supramolekularer Architekturen zuganglich, die sich zur Entwicklung funktioneller Materialen anbieten.

International audience; Phosphine gold(I) aryl acetylide complexes equipped with a central bis(urea) moiety form 1D hydrogen-bonded polymeric assemblies in solution that do not display any optical activity. Chiral co-assemblies are formed by simple addition of an enantiopure (metal-free) complementary monomer. Although exhibiting an intrinsically achiral linear geometry, the gold(I) aryl acetylide fragment is located in the chiral environment displayed by the hydrogen-bonded co-assemblies, as demonstrated by induced circular dichroism (ICD).

We report the synthesis and luminescence properties of a novel platinum(ii)-silver(i) cluster exhibiting supramolecular donor-acceptor dative Pt → Ag bonds as well as d(10)...d(10) argentophilic interactions. This compound was obtained by a self-assembly process upon mixing silver triflate with the [Pt(bdt)(bpy)] (1) building block. The new compound was characterized by infrared, NMR ((1)H, (13)C) and UV-vis spectroscopy. In addition, the molecular structure was unequivocally ascertained by a single-crystal X-ray diffraction study and shows that the assembly is identified as [(Pt2Ag2(o-bdt)2(bpy)2](CF3SO3)2 (2). Remarkably, the structure shows that complex 2 exists as two isomers I and II displaying different types of argentophilic interactions Ag...Ag as well as Pt → Ag dative bonds. These interactions are highly important and turn on phosphorescent emissions at low temperature depending on the nature of the isomer. The photophysical properties of both isomers were investigated and rationalized through TD-DFT calculations. This work paves the way to the synthesis of novel supramolecular assemblies displaying peculiar properties imparted from metallophilic as well as donor-acceptor metal-metal interactions.

A ruthenium coordination complex, incorporating two highly extended pi-systems DIP and two carboxylic groups: [Ru(DIP)2(L-L)]2+ where DIP=4,7-diphenyl-1,10-phenanthroline and L-L=4,4'-dicarboxy-2,2'-bipyridine, is found to be of biological interest. It constitutes an effective nuclear DNA dye for living cells: fluorescent, permeant, biocompatible, high Stokes shift. These features are commented in terms of hydrophobicity and DNA binding. In addition, this complex is shown to internalize a plasmid carrying the enhanced green fluorescent protein (EGFP) gene. Positive results are obtained for gene expression, which is related to condensation of the DNA by this ruthenium agent. This opens up an innovative transfection route based on metal complexes.

Overcoming a long-standing challenge, the o- and p-dithiobenzoquinone iridium complexes [Cp*Ir-o-(η4-C6H4S2)] (6) and [Cp*Ir-p-(η4-C6H4S2)] (7) were rationally synthesized and fully characterized for the first time including the X-ray molecular structure of [Cp*Ir-p-(η4-C6H4S2)] (7). Our strategic approach involves the preparation of the halogenated 1,2- and 1,4-dichloro arene π complexes [Cp*Ir-o-(η6-C6H4Cl2)][BF4]2 (4) and [Cp*Ir-p-(η6-C6H4Cl2)][BF4]2 (5), which are the key molecules for 6 and 7. Subsequent treatment of 4 and 5 with NaSH and halogen displacement provides the target thioquinonoid π complexes 6 and 7 in 88 % and 95 % yields respectively. Further, the coordination chemistry of the o-dithiobenzoquinone iridium complex [Cp*Ir-o-(η4-C6H4S2)] (6) was studied by treating 6 with [(bpy)PtCl2] in the presence of AgOTf, which provided the novel platinum complex [Pt(bpy){Cp*Ir-o-(η4-C6H4S2)}][OTf]2 (10) in 91 % yield. The X-ray molecular structure of 10 is reported and shows as outstanding features the formation of 1D supramolecular assembly, which results from π–π (d = 3.484 A; d = 3.669 A) and Pt···Pt (d = 3.574 A) interactions between individual subunits.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

We report the use of the organometallic linker [Cp*Ir(η4-benzoquinone)] (1b) LIr to construct novel supramolecular one- and two-dimensional (1D and 2D) coordination polymers {[Cu2(LIr)2(CH3CN)(OTf)2][LIr](OTf)}n (3) and {[Ag2(CH3CN)2][LIr]2(OTf)2}n (4). Complex 3 formed a zigzag chain of Cu(I) and Cu(II) centers connected through irido-quinonoid backbones, while complex 4 exhibited argentopilic Ag---Ag d10---d10 contacts at d = 3.638 A and C---H/π interactions between the 1D chain neighbors.

The ion-pairing between the chiral Δ- or Λ-[Ru(bpy)2(Hcmbpy)]2+ (Δ1 or Λ1) and the Δ-Trisphat- (Δ2) (Hcmbpy = 4-carboxy-4‘-methyl-2,2-bipyridine and Trisphat = tris(tetrachlorobenzenediolato)phosphate(V)) is investigated in solution by means of 1H NMR spectroscopy. The Ru−Trisphat ion-pairing adopts two stoichiometries that exchange via a fast dynamic process. The equilibrium constants K and K‘ are calculated for the 1/1 and 1/2 Ru/Trisphat stoichiometries. The constant values are in agreement with Coulombic attractions assisted by a π−π stacking between the bpy ligands of the Ru cation and the aromatic rings of the Trisphat anion. The homochiral pairing is favored as opposed to the heterochiral one, as shown by the respective K‘ values of 4.46 × 105 vs 2.05 × 105 M-2. In the homochiral ion pair, the cationic and anionic propellers adequately fit to optimize the π-stacking interactions and to lead to a dication sandwiched by two anions at the highest Trisphat/Ru ratios.

The chiral supramolecular rhodium triangular hosts [Li⊂(R,R,R)-{Cp*Rh(5-chloro-2,3-dioxopyridine)}3][Δ-Trisphat] (8a) and [Li⊂(S,S,S)-{Cp*Rh(5-chloro-2,3-dioxopyridine)}3][Δ-Trisphat] (8b) have been prepared and separated by fractional crystallization. 1H NMR studies carried out on 8b showed that a slow epimerization process occurs at room temperature, which after 90 days produces approximately a 1:1 mixture of 8a,b, suggesting that the configurational stability is highly enhanced in the trimer host compared to analogous chiral mononuclear species.

A series of iridium-stabilized selenocyclohexadienyls of general formula [Cp*Ir(η5-C6H5–nMenSe)][BF4] {Cp* = η5-C5Me5, n = 0, n = 1, and n = 3} is described, with the selenocyclohexadienyl unit being isolated for the first time by π-coordination to a Cp*Ir moiety. The solid-state structure of one of [Cp*Ir(η5-C6H2Me3Se)][BF4] was determined by single-crystal X-ray diffraction analysis. These compounds are obtained in good yields as orange-red microcrystalline solids by halogen displacement from the related π-bonded arene-chlorinated starting materials using Na2Se as the selenium source. Furthermore, these new compounds display relevant cytotoxic properties towards human ovarian cancer cells.

A new family of ruthenium complexes of general formula [Ru(DIP)(2)(L-2)](2+), where DIP) 4,7-diphenyl-1,10-phenanthroline,a bidentate ligand with an extended aromatic system, was prepared and fully characterized. When L is a monodentate ligand, the following complexes were obtained: L = CF3SO3-1 (2), CH3CN (3), and MeOH (4). When L-2 is a bidentate ligand, the compounds [Ru(DIP)(2)(Hcmbpy)][Cl](2) (5) and [Ru(DIP)(2)(H(2)dcbpy)][Cl](2) ( 6) were prepared (Hcmbpy = 4-carboxy-4'-methyl-2,2-bipyridine, H(2)dcbpy = 4,4'-dicarboxy-2,2'-bipyridine). Complex [Ru(DIP)(2)(MeOH)(2)][OTf](2) (4) displayed a trans configuration of the DIP ligands, which is rare for octahedral complexes featuring DIP bidentate ligands. DFT calculations carried out on 4 showed that the cis isomer is more stable by 12.2 kcal/ mol relative to the trans species. The solution behaviors of monocarboxylic complex [ Ru( DIP) 2( Hcmbpy)][Cl](2) ( 5) and dicarboxylic complex [Ru(DIP)(2)(H(2)dcbpy)][Cl](2) (6) were investigated by H-1 NMR spectroscopy. VT-NMR, concentration dependence, and reaction with NaOD allowed us to suggest that aggregation of the cationic species in solution, especially for 6, originates mainly from hydrogen bonding interactions.

The simplest o-quinone methide (o-QM, 2-methylenecyclohexa-3,5-dienone) has only been detected spectroscopically at temperatures below −100 °C, yet its derivatives have been implicated as highly reactive intermediates in organic reactions, including cycloaddition chemistry and DNA modification because of the high electrophilicity of the exocylic methylene carbon. In striking contrast, o-QM complexes of Cp*Ir and Cp*Rh can be isolated, characterized by X-ray diffraction, and show nucleophilic reactivity at the exocyclic carbon. To explain the differences in structure and reactivity as a function of metal fragment and ligand substitution pattern, we report a series of DFT calculations on Ir, Rh, and heretofore intractable Co congeners, along with a representative (arene)Ru analogue. At the B3LYP level with a variety of basis sets, the bend of the o-QM ligand is predicted to increase from Co to Rh to Ir, confirming solid-state data on complexes from the second- and third-row metals. In addition, an attentuat...

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Treatment of hydroquinone with [Cp*M(solvent) 3 ] [OTf] 2 (M = Rh, Ir) in acetone afforded the π-bonded complexes {[Cp*M(η 5 -semiquinone)] [OTf]} n (M = Rh (la), M = Ir (1b)) in 95% yield. The 1 H NMR spectra of la,b recorded in CD 3 OD indicate strong hydrogen bonding in solution. The crystal structures of la and 1b were determined and exhibit strong intermolecular hydrogen bonding, forming organometallic polymers in which the integrity of the system is maintained by hydrogen bonding between metal-semiquinone subunits. Deprotonation of la produced the related η 4 -quinone complex [Cp*Rh(η 4 -quinone)] (2a), which was fully characterized and its X-ray molecular structure determined. Furthermore, the electrochemical behavior of these η 4 -quinone π-complexes [Cp*M(η 4 -quinone)] (M = Rh (2a), M = Ir (2b)) was investigated and compared to that of the well-known couple quinone/ hydroquinone. The latter are important species in chemistry and biology; their biological action is often linked to their electron-transfer rates and redox behavior.

The racemic triangular supramolecular host [CpRh(5-chloro-2,3-dioxopyridine)](3) (1) was prepared in high yield. Treatment with LiCl followed by addition of silver salt AgOTf gave the triflate salt species [Li subset[CpRh(5-chloro-2,3-dioxopyridine)](3)][OTf] (2). Subsequent anion metathesis using the optically pure chiral shift reagent [Cinchonidinium][Delta-Trisphat] produced a pair of diastereomers [Li subset(R,R,R)-[CpRh(5-chloro-2,3-dioxopyridine)](3)][Delta-Trisphat] (3a) and [Li subset(S,S,S)-[CpRh(5-chloro-2,3-dioxopyridine)](3)][Delta-Trisphat] (3b). The resolution of these diastereomers was achieved by fractional crystallization, and their stereochemistry relationship was established by circular dichroism studies. The X-ray molecular structure of 3a is reported and shows as an outstanding feature a chiral recognition between the Delta-Trisphat anion and a single enantiomer cation [Li subset(R,R,R)-[CpRh(5-chloro-2,3-dioxopyridine)](3)](+) manifested through a pi-pi interaction. (1)H NMR and circular dichroism studies in solution support the solid-state behavior.