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Aza-boron-dipyrromethenes (Aza-BODIPYs) are an increasingly studied class of fluorophores. They can be seen as an azadipyrromethene ("aza-DIPY") ligand rigidified by a metalloid, a boron atom. Based on this idea, a series of complexes of group 13 metals (aluminum and gallium) have been synthesized and characterized. The impact of the metal and of the nature of the substituents of aza-DIPY core were investigated. The photophysical and electrochemical properties were determined, and an X-ray structure of an azaGaDIPY was obtained. These data reveal that azaGaDIPY and azaAlDIPY exhibit significant red-shifted fluorescence compared to their analogue aza-BODIPY. Their emission can go up to 800 nm for the maximum emission length and up to NIR-II for the emission tail. This, associated with their electrochemical stability (no metal release whether oxidized or reduced) makes them a promising class of fluorophores for optical medical imaging. Moreover, X-ray structure and molecular modeling studies have shown that this redshift seems to be more due to the geometry around the boron/metal than to the nature of the metal.

Cationic amidotitanocene complexes [Cp2 Ti(NPhAr)][B(C6 F5 )4 ] (Cp=η5 -C5 H5 ; Ar=phenyl (1 a), p-tolyl (1 b), p-anisyl (1 c)) were isolated. The bonding situation was studied by DFT (Density Functional Theory) using EDA-NOCV (Energy Decomposition Analysis with Natural Orbitals for Chemical Valence). The polar Ti-N bond in 1 a-c features an unusual inversion of σ and π bond strengths responsible for the balance between stability and reactivity in these coordinatively unsaturated species. In solution, 1 a-c undergo photolytic Ti-N cleavage to release Ti(III) species and aminyl radicals ⋅NPhAr. Reaction of 1 b with H3 BNHMe2 results in fast homolytic Ti-N cleavage to give [Cp2 Ti(H3 BNHMe2 )][B(C6 F5 )4 ] (3). 1 a-c are highly active precatalysts in olefin hydrogenation and silanes/amines cross-dehydrogenative coupling, whilst 3 efficiently catalyzes amine-borane dehydrogenation. The mechanism of olefin hydrogenation was studied by DFT and the cooperative H2 activation key step was disclosed using the Activation Strain Model (ASM).

Aza-BODIPYs are an increasingly studied class of fluorophores. They can be seen as an "aza-DIPY" ligand rigidified by a metalloid, a boron atom. Based on this idea, a series of complexes of group 13 metals (aluminum and gallium) have been synthesized and characterized. Impact of the metal and of the nature of the substituents of aza-DIPY core were investigated. The photophysical and electrochemical properties were determined and an X-ray structure of an azaGaDIPY was obtained. These data reveal that azaGaDIPY and azaAlDIPY exhibit significant red-shifted fluorescence compared to their analogue aza-BODIPY. Their emission can go up to 800 nm for the maximum emission length and up to NIR-II for the emission tail. This, associated with their electrochemical stability (no metal release whether oxidized or reduced) make them a promising class of fluorophores for optical medical imaging. Moreover, X-ray structure and molecular modeling studies have shown that this red shift seems to be more due to the geometry around the boron/metal than to the nature of the metal.

International audience; Tame d0 phosphidotitanocene cations stabilized with a pendant tertiary phosphane arm are reported. These compounds were obtained by one-electron oxidation of d1 precursors with [Cp2Fe][BPh4]. The electronic structure of these compounds was studied experimentally (EPR, UV/Vis, and NMR spectroscopy, X-ray diffraction analysis) and through DFT calculations. The theoretical analysis of the bonding situation by using the electron localization function (ELF) shows the presence of π-interactions between the phosphido ligand and Ti in the d0 complexes, whereas dπ–pπ repulsion prevents such interactions in the d1 complexes. In addition, CH–π interactions were observed in several complexes, both in solution and in the solid state, between the phosphido ligand and the phosphane arm. The d0 complexes were found to be light sensitive, and decompose through Ti−P bond homolysis to give TiIII species. A naked d0 phosphidotitanocene cation has been trapped by reaction with diphenylacetylene, yielding a Ti/P frustrated Lewis pair (FLP), which was found to be less reactive than a previously reported Zr analog.

The synthesis and characterization of a range of bis(iminophosphoranyl)phosphide (BIPP) group 4 and coinage metals complexes is reported. BIPP ligands bind group 4 metals in a pseudo fac-fashion, and the central phosphorus atom enables the formation of d0–d10 heterobimetallic complexes. Various DFT computational tools (including AIM, ELF and NCI) show that the phosphorus–metal interaction is either electrostatic (Ti) or dative (Au, Cu). A bridged homobimetallic Cu–Cu complex was also prepared and its spectroscopic properties were investigated. The theoretical analysis of the P–P bond in BIPP complexes reveals that (i) BIPP are closely related to ambiphilic triphosphenium (TP) cations; (ii) the P–P bonds are normal covalent (i.e. not dative) in both BIPP and TP., The synthesis, characterization and computational analysis of a range of bis(iminophosphoranyl)phosphide (BIPP) group 4 and coinage metals complexes is reported. White phosphorus was used to install the central phosphorus atom.

Six ruthenium(II)- and four gold(I)-phosphine based complexes were synthesized and fully characterized. Some of them displayed strong antiproliferative properties for several types of cancer including colon, breast, and lung. Notably, two of the Ru(II) complexes displayed an IC50 of around 2 μM, which is exceptional for these types of complexes. The dramatic impact of the nature of the arene coordinated on the ruthenium center was clearly evidenced.

International audience; Herein we report the synthesis of new ditopic ligands, which consist of a phenoxy group and N,N,N'trisubstituted amidines linked by a methylene spacer (L1-L4). Their coordination chemistry has been studied/investigated with Zn(II) and Al(III). Alkane elimination route between the phenol-amidine proligands (L1H-L4H) and Et2Zn led to dinuclear complexes [(L1-L4)ZnEt]2 (1a-4a) in which the Zn centers are chelated by phenoxyamidine ligands and bridged through the oxygen atom of the phenoxy groups. Salt metathesis reaction between two equivalents of the sodium amidine phenate L1Na and ZnCl2 led to a bis-chelate chiral spiro-complex (L12Zn) 1a'. Analogous alkane elimination route between AlMe3 and the phenol-amidine proligands L1H-L4H allowed the preparation of the mononuclear complexes [(L1-L4)AlMe2] (1b-4b). The phenoxyamidine-Al and Zn complexes have been characterized by NMR spectroscopy, elemental analysis and/or high resolution ESI-MS. The solid state structures of the proligands [L1H2][Br] and L2H as well as of six complexes have been established by single crystal X-ray diffraction analysis. Fluxional properties of the proligands L1H-L2H and of the complexes 1a and 2b have been investigated by VT NMR experiments. In the presence of an alcohol source, complexes 1a-4a and 1b-4b were used as initiators for the controlled ring-opening polymerization (ROP) of rac-lactide to afford atactic polylactic acid (PLA).

Rational design of ruthenium complexes with optimized ligands is a promising approach to modulate their stability and antiproliferative effects in cancerous cells. The release of ligands from the coordination sphere of the ruthenium complexes can lead to the formation of biologically active Ru species that are able to exert cytotoxic effects. Herein, we have studied this approach on four ruthenium(II) complexes bearing (3,5-cycloheptadienyl)diphenylphosphine or (cycloheptyl)diphenylphosphine and ethylbenzoate or p-cymene and an unusual bimetallic analogue. The stability of the complexes was investigated in DMF as well as DMEM/FBS using 1H and 31P{1H} NMR spectroscopy. We studied the photo-cytotoxicities of the complexes in two cell lines – HeLa and RPE-1 – to understand their behavior and cytotoxicity upon ligand dissociation. All complexes showed moderate to high cytotoxicity in the two cell lines upon light irradiation.

Three new gold(I)-coumarin-based trackable therapeutic complexes and two non-trackable analogues have been synthesised and fully characterised. They all display anti-proliferative properties on several types of cancer cell lines, including those of colon, breast, and prostate. Two complexes displayed significant anti-inflammatory effects; one displayed pro-inflammatory behaviour; this highlights the impact of the position of the fluorophore on the caffeine scaffold. Additionally, the three coumarin derivatives could be visualised in vitro by two-photon microscopy.

International audience; The synthesis and characterization of a series of arene ruthenium complexes bearing either (3,5-cycloheptadienyl)diphenylphosphine or (cycloheptyl)-diphenylphosphine are reported. Upon irradiation or heating, all these complexes lose their arene ligand but then exhibit a different behavior depending on the nature of the phosphine ligand. (Cycloheptadienyl)phosphine complexes 1 and 3 give a cationic dinuclear Ru complex 5 for which the two Ru atoms are bridged by three chlorido ligands and flanked by two tridendate (cycloheptadienyl)phosphines. (Cycloheptyl)-diphenylphosphine complexes 2 and 4 undergo arene exchange when toluene is used as solvent or degrade in dithloromethane. ATRA catalytic trials conducted in parallel with these complexes using CCl4 and styrene as standard substrates, highlighted the deep impact of the dienyl moiety on the results. Under smooth conditions (UV irradiation or moderate heating), only (cycloheptyl)phosphine derivatives give Karasch adduct in satisfactory yields. Their performance was considerably improved by combining irradiation and heating. At higher temperature, cationic dinuclear complex 5 was revealed as active and robust, giving turnover numbers as high as 9700 when tetradecene and CCl4 were used as substrates.

While N-heterocyclic carbenes (NHC) are ubiquitous ligands in catalysis for organic or industrial syntheses, their potential to form transition metal complexes for medicinal applications has still to be exploited. Within this frame, we synthesized new homo- and heterobimetallic complexes based on the Au(I)-NHC scaffold. The compounds were synthesized via a microwave-assisted method developed in our laboratories using Au(I)-NHC complexes carrying a pentafluorophenol ester moiety and another Au(I) phosphane complex or a bipyridine ligand bearing a pendant amine function. Thus, we developed two different methods to prepare homo- and heterobimetallic complexes (Au(I)/Au(I) or Au(I)/Cu(II), Au(I)/Ru(II), respectively). All the compounds were fully characterized by several spectroscopic techniques including far infrared, and were tested for their antiproliferative effects in a series of human cancer cells. They showed moderate anticancer properties. Their toxic effects were also studied ex vivo using the precision-cut tissue slices (PCTS) technique and initial results concerning their reactivity with the seleno-enzyme thioredoxin reductase were obtained.

Chiral and achiral silylphosphine-boranes were prep ared in high yields by reaction of phosphide boranes with halogenosilanes. Their reaction at roo m temperature with Michael acceptors afforded 1,4-addition products as silylenol ether o r ketone derivatives in good to excellent yields. In the case of the 2,3-dihalogeno-maleimides, the d ouble addition of silylphosphine-borane led to the corresponding trans-diphosphine-boranes in 86% yield. Noteworthy, the r eaction of Pchirogenic silylphosphine-boranes with enones affor ded the phospha-Michael adducts without racemization at the P-center. While the silylphosph ine-boranes have been scarcely described so far, these compounds demonstrate their great intere st for the synthesis of chiral and achiral functionalized organophosphorus compounds.

Gold phosphine complexes, such as auranofin, have been recognized for decades as antirheumatic agents. Clinical trials are now underway to validate their use in anticancer or anti-HIV treatments. However, their mechanisms of action remain unclear. A challenging question is whether the gold phosphine complex is a prodrug that is administered in an inactive precursor form or rather that the gold atom remains attached to the phosphine ligand during treatment. In this study, we present two novel gold complexes, which we compared to auranofin and to their phosphonium analogue. The chosen ligand is a phosphine-based smart probe, whose strong fluorescence depends on the presence of the gold atom. The in vitro biological action of the gold complexes and the phosphonium derivative were investigated, and a preliminary in vivo study in healthy zebrafish larvae allowed us to evaluate gold complex biodistribution and toxicity. The different analyses carried out showed that these gold complexes were stable and behaved differently from phosphonium and auranofin, both in vitro and in vivo. Two-photon microscopy experiments demonstrated that the cellular targets of these gold complexes are not the same as those of the phosphonium analogue. Moreover, despite similar IC50 values in some cancer cell lines, gold complexes displayed a low toxicity in vivo, in contrast to the phosphonium salt. They are therefore suitable for future in vivo investigations.

A new family of cationic Ti complexes 4′ with a pendant phosphine of general formula [CpCpPTiOAr][BPh4] (Cp = η5-C5H5; CpP = η5-C5H4(CMe2)PR2) has been prepared in four steps from 6,6-dimethylfulvene. These complexes were designed to behave as Ti based frustrated Lewis pairs (FLPs). The key synthetic step is a reduction–oxidation sequence from [CpCpPTiClOAr] complexes 3 using lithium phosphide salts as the reductants and ferricinium tetraphenylborate as the oxidant. Four complexes have been structurally characterized by X-ray diffraction and show elongated Ti–P bonds, above 2.60 A. One complex (4b′: OAr = 2,6-Me2C6H3; PR2 = PCy2) reacted with benzaldehyde to form a typical FLP activation product. Complex 4b′ also reacted with 2 equiv of trans-chalcone to form a 10-membered Ti phosphonium macrocycle (6b′) by extrusion of 6,6-dimethylfulvene.

Two p-cymene-ruthenium complexes 1 and 2 were isolated in high yields by treating the [RuCl2(p-cymene)]2 dimer with new hybrid phosphane- or NHC-linked diene ligands. Both complexes were fully characterized by NMR spectroscopy, and the molecular structure of the ruthenium–p-cymene complex 1, containing the phosphane–diene ligand system, was determined by X-ray diffraction analysis. The catalytic activities of both compounds were probed in atom-transfer radical addition (ATRA) and polymerization (ATRP), in the cyclopropanation of olefins, in the ring-opening metathesis polymerization (ROMP) of norbornene, and in the synthesis of enol esters from hex-1-yne and 4-acetoxybenzoic acid.

A series of (η6-p-cymene)ruthenium(II)- and osmium(II) complexes of porphyrin-phosphane derivatives have been synthesized as potential bimetallic theranostic candidates. The photophysical and electrochemical properties were investigated, and these species desirably exhibit no or almost no photoinduced intramolecular atom, energy, and electron transfer between the dye and the metallic fragment. These favorable features are mostly associated with the presence of their long chain (i.e., ∼ 1 nm) separating the two functional units. Interestingly, a decrease in emission intensity and lifetimes (up to 35-fold) has been observed, which was ascribed to a small heavy atom effect. This effect is possible as a chain folding driven by an intramolecular H-bond (N–H···Cl–M).

While N-heterocyclic carbenes (NHC) are ubiquitous ligands in catalysts for organic or industrial synthesis, their potential to form transition metal complexes for medicinal applications has still to be exploited. Within this frame, new Au(I)-NHC compounds have been synthesized and structurally characterized via different methods. The solid state structure of one of these compounds was also established by X-ray crystallography. Of note, three of them bear a pentafluorophenolic ester group as a possible "activable" moiety for further functionalization, which allowed tethering an alkyl amine ligand or another Au(I)-phosphine complex featuring a pendant amine function via microwave activation. The obtained compounds have been tested for their antiproliferative effects in human ovarian cancer A2780 cells, and in non-tumorigenic human embryonic kidney HEK-293T cells, showing promising anticancer properties and a certain selectivity towards cancerous cells. (C) 2014 Elsevier B.V. All rights reserved.

International audience; A novel Ti/111In-heterometallic radiotheranostic along with non-radioactive Ti/In, Ti/Lu, and Ti/Y analogues has been reported, thanks to the design of a challenging synthesis of the first titanocene-DOTA ligand. The corresponding titanocene-BODIPY complex was developed for in vitro tracking by optical imaging. The different complexes were characterized and their antiproliferative properties were evaluated on three cancer cell lines (A2780, B16F1, and PC3). As a proof of concept, initial studies in healthy mice were performed with a Ti/111In derivative to obtain information about its uptake, its biodistribution, and its excretion. Confocal microscopy experiments were performed with fluorescent complexes to track it in vitro.

International audience; Two new gold(I)–BODIPY–imidazole based trackable therapeutic bimetallic complexes have been synthesized and fully characterized. They display strong antiproliferative properties on several types of cancers including colon, breast, and prostate and one of them presents a significant anti-inflammatory effect. Additionally, the two compounds could be visualised in vitro by confocal microscopy in the submicromolar range.

The influence of hydrogen pressure on the hydrosilylation of ketones catalyzed by [((S)-SYNPHOS)Rh(nbd)]OTf has been studied. We have notably demonstrated that hydrogen significantly affected the outcome of the reaction while not being consumed as stoichiometric reducing agent. In THF, diethyl ether or toluene, the hydrogen pressure exceedingly accelerated the hydrosilylation reaction and preserved or even improved the enantioselectivity of the process. In CH2Cl2, the rhodium catalyst also showed generally higher catalytic activity under hydrogen pressure. Most serendipitously, several ketones were found to give products of absolute opposite configuration upon performing the hydrosilylation under argon atmosphere or under hydrogen pressure. Copyright © 2014 John Wiley & Sons, Ltd.

A new series of gold(I) N-heterocyclic carbene (NHC) complexes based on xanthine ligands have been synthesized and characterized by mass spectrometry, NMR, and X-ray diffraction. The compounds have been tested for their antiproliferative properties in human cancer cells and nontumorigenic cells in vitro, as well as for their toxicity in healthy tissues ex vivo. The bis-carbene complex [Au(caffein-2-ylidene)(2)] [BF4] (complex 4) appeared to be selective for human ovarian cancer cell lines and poorly toxic in healthy organs. To gain preliminary insights into their actual mechanism of action, two biologically relevant in cellulo targets were studied, namely, DNA (more precisely a higher-order DNA structure termed G-quadruplex DNA that plays key roles in oncogenetic regulation) and a pivotal enzyme of the DNA damage response (DDR) machinery (poly-(adenosine diphosphate (ADP)-ribose) polymerase 1 (PARP-1), strongly involved in the cancer resistance mechanism). Our results indicate that complex 4 acts as an efficient and selective G-quadruplex ligand while being a modest PARP-1 inhibitor (i.e., poor DDR impairing agent) and thus provide preliminary insights into the molecular mechanism that underlies its antiproliferative behavior.

I�-Allyltitanium complexes, generated in situ from 1,3-dienes and Cp2TiH, react with benzotriazole derivatives to give homoallylic amines in good yields. Under similar conditions, triple cascade reactions (allyltitanation followed by cationic 2-aza-Cope rearrangement followed by a second allyltitanation) occur from bis(benzotriazolyl) compounds affording a straightforward route to homoallyl-(E)-homocrotylamines. A theoretical study provides further insight into the factors that govern the selectivity of this sequence of reactions. The titanium-promoted reductive coupling of 1,3-dienes with bis(benzotriazolyl) compounds as substrates led selectively to homoallyl-homocrotylamines through a triple cascade reaction (allyltitanation - cationic 2-aza-Cope rearrangement - allyltitanation). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

International audience; We report that the cationic phosphidozirconocene complex [(eta(5)-C5H5)(2)Zr(PCy2)][CH3B(C6F5)(3)] (II) reacts with azobenzene, resulting in the expedient formation of Zr complex (2) bound to a tridentate PNN ligand. This reaction proceeds by a mechanism of cooperative nucleophilic substitution of hydrogen. The intermediate sigma(H) adduct (1) has been characterized by NMR spectroscopy.

International audience; A series of new heterodinuclear luminescent complexes with two different organic ligands have been synthesized and characterized. A luminescent Ru-II(polypyridine) moiety and a metal-based anticancer fragment (AuCl, (p-cymene)RuCl2, (p-cymene)OsCl2, (Cp*)RhCl2, or Au-thioglucose) are the two general features of these complexes. All of the bimetallic compounds have been evaluated for their antiproliferative properties in vitro in human cancer cell lines. Only the complexes containing an Au(I) fragment exhibit antiproliferative activity in the range of cisplatin or higher. The photophysical and electrochemical properties of the bimetallic species have been investigated, and fluorescence microscopy experiments have been performed successfully. The most promising bimetallic cytotoxic complexes (i.e., with the Au-thioglucose scaffold) have shown to be easily taken up by cancer cells at 37 degrees C in the cytoplasm or in specific organelles. Interestingly, experiments repeated at 4 degrees C showed no uptake of the bimetallic species inside cells, which confirms involvement of active transport processes. To evaluate the role of glucose transporters in the cell uptake of the gold complexes, inhibition of the GluT-1 (glucose transporter isoform with high level of expression in cancer cells) was achieved, showing only scarce influence on the compounds' uptake. Finally, the observed absence of interactions with nucleic acid model structures suggests that the gold compounds may have different intracellular targets with respect to cisplatin.

International audience; Neutral phosphidozirconocene complexes [Cp2Zr(PR2)Me] (Cp=cyclopentadienyl; 1a: R=cyclohexyl (Cy); 1b: R=mesityl (Mes); 1c: R=tBu) undergo insertion into the Zr-P bond by non-enolisable carbonyl building blocks (O=CRR), such as benzophenone, aldehydes, paraformaldehyde or CO2, to give [Cp2Zr(OCRRPR2)Me] (3-7). Depending on the steric bulk around P, complexes 3-7 react with B(C6F5)(3) to give O-bridged cationic zirconocene dimers that display typical frustrated Lewis pair (FLP)/ambiphilic ligand behaviour. Thus, the reaction of {[Cp2Zr(-OCHPhPCy2)][MeB(C6F5)(3)]}(2) (10a) with chalcone results in 1,4 addition of the Zr+/P FLP, whereas the reaction of {[Cp2Zr(-OCHFcPCy(2))][MeB(C6F5)(3)]}(2) (11a; Fc=(C5H4)CpFe) with [Pd((3)-C3H5)Cl](2) yields the unique Zr-Fe-Pd trimetallic complex 13a, which has been characterised by XRD analysis.

International audience; Ten metal-based complexes and associated ligands have been synthesized and characterized. One of the metal ligands is a coumarin-phosphine derivative, which displays tunable fluorescence properties. The fluorescence is quenched in the case of the free ligand and ruthenium and osmium complexes, whereas it is strong for the gold complexes and phosphonium derivatives. These trends were rationalized by theoretical calculations, which revealed non-radiative channels involving a dark state for the free ligands that is lower in energy than the emissive state and is responsible for the quenching of fluorescence. For the Ru-II and Os-II complexes, other non-radiative channels involving the manifold of singlet and triplet excited states may play a role. The anti-proliferative properties of all the compounds were evaluated in cancer cell lines (SW480, HCT116, MDA-MB-231 and MCF-7); higher IC50 values were obtained for gold(I) complexes, with the free ligands being only weakly cytotoxic.

Methyl abstraction from neutral [Cp2ZrMe(ERR′)] complexes 1 (E = N, P; R, R′ = alkyl, aryl) with either B(C6F5)3 or [Ph3C][B(C6F5)4] results in the formation of [Cp2Zr(ERR′)][X] complexes 2 (X– = MeB(C6F5)3–, B(C6F5)4–). The X-ray structure of amido complexes [Cp2Zr(NPh2)][MeB(C6F5)3] (2d) and [Cp2Zr(NtBuAr)][B(C6F5)4] (2e′, Ar = 3,5-C6H3(CH3)2) is reported, showing a sterically dependent Zr/N−π interaction. Complexes 2 catalyze the hydrogenation of electron-rich olefins and alkynes under mild conditions (room temperature, 1.5 bar H2). Complex 2e binds CO2, giving [Cp2Zr(CO2)(NtBuAr)]2[MeB(C6F5)3]2 (3e). Amido complex 2d reacts with benzaldehyde yielding [Cp2Zr(OCH2Ph)((OC)PhNPh2)][MeB(C6F5)3] (7d). Phosphido complex [Cp2Zr(PCy2)][MeB(C6F5)3] (2a) reacts with diphenylacetylene to yield frustrated Lewis pair [Cp2Zr(PhCCPh)(PCy2)][MeB(C6F5)3] (8a) which further reacts with a range of carbonyl substrates.

The design of trackable anticancer agents is of major interest for the future development of therapeutics based on nonplatinum metal complexes such as Ru(II), Os(II), or Au(I) derivatives, and more particularly for the understanding of the mechanism of action of these metal-based drugs. This review reports the synthesis and the first biological studies of original trackable complexes, in which the metal complex was coupled to an imaging probe, such as a fluorophore (coumarin, borodipyrromethene derivative (BODIPY), porphyrin), or a chelating agent (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)) for radioisotopic imaging PET (positron emission tomography) or SPECT (single photon emission computed tomography). In the case of fluorescent theranostics, the photophysical properties of the different compounds were studied and the cell uptake could be evaluated on different cell lines, by microscopy imaging. A fluorescent smart probe based on coumarin-phosphine, whose fluorescence strongly depends on the coordination of the metal was also studied, revealing a nonusual cellular target with respect to the classical gold therapeutic systems. In the last section, the synthesis of new potential fluorescent trackable-radiotherapeutics is also presented.

A molecularly defined new phosphine–diolefin cubane copper pre-catalyst used at 1.25 mol % under mild conditions promotes the coupling of pyrazoles to functionalised aryl and heteroaryl bromides, which hold a variety of functional groups. This versatile phosphorus-based system was thus successfully used, under identical conditions, for the coupling of a large scope of heteroaromatics to selectively produce pyridinyl- and pyrimidinyl-pyrazoles, as well as several novel furyl-, thienyl- and thiazolyl-substituted pyrazoles. The careful investigation of coupling with the analogous aryl and heteroaryl chlorides clearly indicated that for specifically activated chloroarenes a direct nucleophilic aromatic substitution (SNAr) is easily achieved in the absence of any copper and ligand. These results are pertinent with regards to the reported protocols in which copper–ligand systems have been claimed as useful for coupling activated chloroarenes.

The targeting of higher-order DNA structures has been thoroughly developed with G-quadruplex DNA but not with other structures like branched DNA (also known as DNA junctions). Because these alternative higher-order DNA architectures might be of high biological relevance, we implemented a high-throughput version of the FRET melting assay that enabled us to map the interactions of a candidate with four different DNA structures (duplex- and quadruplex DNA, three- and four-way junctions) in a rapid and reliable manner. We also introduce a novel index, the BONDS (branched and other noncanonical DNA selectivity) index, to conveniently quantify this differential affinity.

(3,5-Cycloheptadienyl)diphenylphosphine is easily synthesized from the reaction of diphenylphosphine with 1,3,5-cycloheptatriene. This new phosphine-diene has been coordinated as a monodentate P ligand with Pt, Pd, Au, Ni, and Ru; as a bidentate (P, olefin) ligand with Pt and Pd; and as a tridentate (P, diene) ligand with Rh. Fluxional properties of several complexes have been studied via NMR experiments and theoretical consideration.

Motivated by our preliminary results on Cp2TiF 2-catalysed 1,4-hydrosilylation of monosubstituted dienes, we assessed the performance of several titanium complexes for the hydrosilylation of 2,3-dimethylbutadiene, a representative bulky diene. An open-bent titanocene complex Me2C(C5H4)2TiMe 2 performed the best and proved to be efficient for the hydrosilylation of a variety of substrates such as disubstituted dienes, activated alkenes, and even an acetylene. © Georg Thieme Verlag Stuttgart - New York.

A series of bimetallic titanium-ruthenium complexes of general formula [(η(5)-C(5)H(5))(μ-η(5):κ(1)-C(5)H(4)(CR(2))(n)PR'R'')TiCl(2)](η(6)-p-cymene)RuCl(2) (n = 0, 1, 2 or 4; R = H or Me; R' = H, Ph, or Cy; R'' = Ph or Cy) have been synthesized, including two novel compounds as well as two cationic derivatives of formula [(η(5)-C(5)H(5))(μ-η(5):κ(1)-C(5)H(4)(CH(2))(n)PPh(2))TiCl(2)] [(η(6)-p-cymene)RuCl](BF(4)) (n = 0 or 2). The solid state structure of two of these compounds was also established by X-ray crystallography. The complexes showed a cytotoxic effect on human ovarian cancer cells and were markedly more active than their Ti or Ru monometallic analogues titanocene dichloride and RAPTA-C, respectively. Studies of cathepsin B inhibition, an enzyme involved in cancer progression, showed that enzyme inhibition by the bimetallic complexes is influenced by the length of the alkyl chain in between the metal centers. Complementary ESI-MS studies provided evidence for binding of a Ru(II) fragment to proteins.

Redox properties of three cationic tantalocene hydroxo complexes, [Cp*(CpR)Ta V OHCl] + , with one pentamethylated cyclopentadienyl ligand, Cp* = η 5 -C 5 Me 5 , Me = CH 3 , and one monosubstituted cyclopentadienyl ligand, CpR, Cp = C 5 H 4 , R = H, SiMe 3 or (CH 2 ) 3 NC 4 H 4 , as well as of an oxo complex with the pyrrole-containing ligand, Cp*(Cp(CH 2 ) 3 NC 4 H 4 )TaOCl, have been studied in acetonitrile solutions with cyclic voltammetry in the ranges of the Ta(V) reduction to Ta(IV) and to Ta(III). Both transitions are irreversible due to the dissociation of reduced complexes with the loss of their chloride ligand. The mechanism of hydroxo complex reduction is discussed in terms of its reversible deprotonation/protonation equilibrium with the corresponding oxo complex, Cp*(CpR)TaOCl. The variation of the reduction potential for the Ta(V)/Ta(IV) transition in the negative direction in the series of tantalocene complexes: dichloride > hydroxo > oxo, as well as the difference in the behavior of the reduced (Ta(IV)) complexes (stable for dichloride but losing their chloride ligand for hydroxo and oxo complexes) was explained by the increase of the electronic density at the central metal in this series, correlated with the weakening of the Ta–Cl bond and its easier dissociation. The tantalocene centers were immobilized inside a polypyrrole matrix on the electrode surface by electropolymerization of the cationic complex [Cp*(Cp(CH 2 ) 3 NC 4 H 4 )TaOHCl] + . This was possible after removal of the “free” chloride ions from the polymerization bath by their precipitation upon addition of TlPF 6 . The corresponding polymer, poly[Cp*(Cp(CH 2 ) 3 NC 4 H 4 )TaOHCl], was found to be electroactive in contact with a background electrolyte, giving a redox response both in the polymer matrix and tantalocene potential ranges. The mechanism of the immobilized tantalocene complex transformation was the same as that for the same species dissolved in solution.

By combining an ever-increasing number of catalysts or catalytic functions, cooperative catalysis is a research area that grows fast. In the field, “early–late” heterobimetallic complexes are rather old objects but they still continue to fascinate chemists because of their latent reactivity. After a brief and concise overview of cooperative catalysis, this review focuses on “early–late” heterobimetallic complexes that were used in catalysis over the last decades. Examples of dual catalysis using early and late metal partners are also described. This chapter ends with an opening towards therapeutic applications of “early–late” heterobimetallic complexes.

Conjugated dienes are able to react as 1,2- or 1,4-dicarbanions by coordination on Ti(II) moiety. These two possibilities are exemplified in this letter with isoprene, myrcene and several aldehydes to give 1,4- and 1,6-diols. When allowed to react with esters at room temperature, the titanium–diene complexes lead to cyclopentenol derivatives. Surprisingly, when this reaction is performed at lower temperature (−40 °C), allylic ketones are formed with high regio and diastereoselectivities.

Four new red BODIPY–gold(I) theranostic compounds were synthesized. Some of them were vectorized by tethering a biovector (glucose or bombesin derivatives) to the metallic center. Their photophysical properties were studied. Additionally, their cytotoxicity was examined on different cancer cell lines and on a normal cell line, they were tracked in vitro by fluorescence detection, and their uptake was evaluated by ICP-MS measurements.

Exposure of a THF solution of tantalocene dichloride complexes (η 5 -Cp*)TaCl 2 (η 5 -C 5 H 4 -SiMe 3 ) (1) and (η 5 -Cp*)TaCl 2 (η 5 -C 5 H 5 ) (2) to the ambient atmosphere for 12 h leads to the formation of new tantalum(V) cationic hydroxo complexes [(η 5 -Cp*)TaCl(OH)(η 5 -C 5 H 4 SiMe 3 )] + -Cl- (3) and [(η 5 -Cp*)TaCl(OH)(η 5 -C 5 H 5 )]+Cl - (4). This oxidation reaction is more rapid under oxygen atmosphere since the hydroxo complexes are obtained in better yields within only 15 min. The hydroxo complexes are easily deprotonated by base to generate oxo complexes 5 and 6, which, in turn, react with trimethylsilyl triflate, giving the corresponding cationic silylated complexes 7 and 8. All structures are confirmed by NMR, IR, and X-ray diffraction.

A series of new titanocene phosphanes 3–6 have been prepared by replacing both chloride atoms at the titanium atom of the complexes [TiCl2(η5-C5H5){η5-C5H4(CH2)2PR2}] (1: R = Ph; 2: R = Cy) by sodium fluoride or sodium benzoate in two-phase systems. Treatment of these new metalloligands with the binuclear complex [(p-cymene)RuCl2]2 affords the targeted titanocene difluoride and titanocene dibenzoate bimetallic ruthenium complexes 8–11. The first chiral Ti–Ru bimetallic complex 12 bearing a binaphthyloxy ligand at the titanium centre has been synthesised in this way. In each series, an X-ray crystal structure has been determined. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

The reaction of the titanocene diphosphine {(η5-C5H5)[η5-C5Me3-1,2-(PPh2)2]TiCl2} (TiPHOS; 1) with [Rh(COD)2](OTf) led to the new early−late heterobimetallic complex [(TiPHOS)Rh(COD)](OTf) (2), who...

The reaction of the phosphine functionalised titanium half-sandwich complexes 7, 9 and 10 with the binuclear complex [(p-cymene)RuCl2]2 allowed the access to three new early-late bimetallic complexes (p-cymene)[(μ-η5:η1-C5H4(CH2)nPR2)TiX3]RuCl2 (11–13). The structure of 11 (n = 0, X = Cl) has been confirmed by X-ray diffraction. The ruthenium titanium half-sandwich bimetallic complexes so formed and the ruthenium titanocene analogues 4–6 catalyse the addition of ethyl diazoacetate to styrene with high selectivity toward cyclopropanation versus metathesis contrary to the monometallic complexes (p-cymene)RuCl2PR3.

The titane–ruthenium heterobimetallic compounds ( p -cymene)[(η 5 -C 5 H 5 )(μ-η 5 :η 1 -C 5 H 4 (CH 2 ) m PR 2 )TiCl 2 ]RuCl 2 4 – 6 have been revealed to be quite good catalysts for the addition of formic acid to 1-hexyne and phenylacetylene. These preliminary results led us to synthesize new tetrametallic complexes 10 – 12 via the reaction of the titanocene phosphanes 1 – 3 with the polymer [Ru(CO) 2 (μ-O 2 CH)] n . Their catalytic ability for the enol esters formation has been studied.

The reaction of the titanocene monophosphanes ( 1 – 4 ) with the dimer [( p -cymene)RuCl 2 ] 2 gives the heterobimetallic compounds ( p -cymene)[(η 5 -C 5 H 5 )(μ-η 5 :η 1 -C 5 H 4 (CR 2 ) n PR′ 2 )TiCl 2 ]RuCl 2 ( 5 – 8 ). The structure of 8 , determined by X-ray diffraction, is reported here. A preliminary assessment of the performance of these complexes in ring-closing metathesis (RCM) revealed an excellent Ti–Ru–allenylidene pre-catalyst 12 .

The influence of hydrogen pressure on the hydrosilylation of ketones catalyzed by [((S)-SYNPHOS)Rh(nbd)]OTf has been studied. We have notably demonstrated that hydrogen significantly affected the outcome of the reaction while not being consumed as stoichiometric reducing agent. In THF, diethyl ether or toluene, the hydrogen pressure exceedingly accelerated the hydrosilylation reaction and preserved or even improved the enantioselectivity of the process. In CH2Cl2, the rhodium catalyst also showed generally higher catalytic activity under hydrogen pressure. Most serendipitously, several ketones were found to give products of absolute opposite configuration upon performing the hydrosilylation under argon atmosphere or under hydrogen pressure. Copyright © 2014 John Wiley & Sons, Ltd.

Terminal titanium imido complexes of the general formula [Ti(N(t)Bu)Cl{CH(Ph2PNR)2}] 4 (R = Ph, (i)Pr, (t)Bu) are reported. These compounds were synthesized from the corresponding Li adducts 3 of BIPMH (bis(iminophosphoranyl)methanide) and Mountford's complex [Ti(N(t)Bu)Cl2(Py)3]. The crystal structures of two of the Ti complexes (R = Ph, (t)Bu) and two of the Li compounds (R = (i)Pr, (t)Bu) are reported. Dynamic solution NMR spectroscopy reveals a dynamic isomerisation process in the case of the Ti complex 4c (R = (t)Bu). DFT studies showed that this dynamic process comes from steric repulsion between the imido ligand and the (t)Bu N-substituents on the BIPMH ligand. Complexes 4 were tested in alkyne hydroamination; 4a (R = Ph) displayed modest catalytic activity in the reaction of aniline with phenylacetylene.