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A salt metathesis synthetic strategy is used to access rare tantalum/coinage metal (Cu, Ag, Au) heterobimetallic complexes. Specifically, complex [Li(THF) 2 ][Ta(C t Bu)(CH 2 t Bu) 3 ], 1 , reacts with (IPr)MCl (M = Cu, Ag, Au, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) to afford the alkylidyne-bridged species [Ta(CH 2 t Bu) 3 (μ-C t Bu)M(IPr)] 2-M . Interestingly, π-bonding of group 11 metals to the Ta─C moiety promotes a rare alkylidyne alkyl to bis-alkylidene tautomerism, in which compounds 2-M are in equilibrium with [Ta(CH t Bu)(CH 2 t Bu) 2 (μ-CH t Bu)M(IPr)] 3-M . This equilibrium was studied in detail using NMR spectroscopy and computational studies. This reveals that the equilibrium position is strongly dependent on the nature of the coinage metal going down the group 11 triad, thus offering a new valuable avenue for controlling this phenomenon. Furthermore, we show that these uncommon bimetallic couples could open attractive opportunities for synergistic reactivity. We notably report an uncommon deoxygenative carbyne transfer to CO 2 resulting in rare examples of coinage metal ketenyl species, ( t BuCCO)M(IPr), 4-M (M = Cu, Ag, Au). In the case of the Ta/Li analogue 1 , the bis(alkylidene) tautomer is not detected, and the reaction with CO 2 does not cleanly yield ketenyl species, which highlights the pivotal role played by the coinage metal partner in controlling these unconventional reactions.

This work investigates the electron-donating capabilities of two 10-π electron nitrogen bridgehead bicyclic [5,6]-fused ring systems, imidazo[1,2- a ]pyridine and imidazo[1,5- a ]pyridine rings. Eight compounds with varying positions of electron-withdrawing moieties (TCF or DCI) coupled to the imidazopyridine ring were synthesized and studied. DCI-containing compounds ( Ib - IVb ) exhibited a purely dipolar nature with broad absorption bands, weak fluorescence, large Stokes shifts, and strong solvatochromism. In contrast, TCF-containing compounds ( Ia - IVa ) demonstrated diverse properties. Imidazo[1,2- a ]pyridine derivatives Ia and IIa were purely dipolar, while imidazo[1,5- a ]pyridine derivatives IIIa and IVa displayed a cyanine-like character with intense absorption and higher quantum yields of emission. The observed gradual red shift in optical properties with changing electron-donor groups ( IIb < Ib < IIIb < IVb ) and ( IIa < Ia < IIIa < IVa ) underscores the stronger electron-donor character of imidazo[1,5- a ]pyridine compared to that of imidazo[1,2- a ]pyridine. Furthermore, crystalline powders of imidazo[1,2- a ]pyridine derivatives exhibited fluorescence despite minimal emission in solution. Two compounds ( Ib and IVa ) were successfully formulated into nanoparticles for potential in vivo imaging applications in zebrafish embryos.

We report the synthesis and absolute configuration (AC) of a chiral isotopologue of syn -cryptophane-B. Low chiral signatures were measured by polarimetry and electronic circular dichroism, whereas most significant chiroptical effects were observed by vibrational circular dichroism (VCD) and Raman optical activity (ROA). The comparison of experimental VCD and ROA spectra with those predicted by DFT calculations allows the determination of the AC of the two enantiomers as (-) 589 - MP - syn - 2 and (+) 589 - PM - syn - 2 .

We report in this article the synthesis, the X-ray crystal structure of compound syn - 2 , and its binding properties with cesium and thallium in aqueous solution under basic conditions. Compound syn - 2 is the diastereomeric compound of anti - 1 that shows very high affinity for cesium and thallium in aqueous solution under the same conditions. Despite the close structural similarities that exist between the syn - 2 and anti - 1 compounds, they show large discrepancy in their ability to bind cesium and thallium cations in the same conditions. Indeed, the syn - 2 derivative has a lower affinity for these two cationic species and the binding constants are several orders of magnitude lower than those found for its congener. The large differences in affinity observed with these two compounds can be explained by the relative position of the six hydroxyl groups to each other., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

We report an original alkane elimination approach, entailing the protonolysis of triisobutylaluminum by the acidic hydrides from Cp*IrH 4 . This strategy allows access to a series of well-defined tri- and tetranuclear iridium aluminum polyhydride clusters, depending on the stoichiometry: [Cp*IrH 3 Al( i Bu) 2 ] 2 ( 1 ), [Cp*IrH 2 Al( i Bu)] 2 ( 2 ), [(Cp*IrH 3 ) 2 Al( i Bu)] ( 3 ), and [(Cp*IrH 3 ) 3 Al] ( 4 ). Contrary to most transition-metal aluminohydride complexes, which can be considered as [AlH x +3 ] x- aluminates and LnM + moieties, the situation here is reversed: These complexes have original structures that are best described as [Cp*IrH x ] n - iridate units surrounding cationic Al(III) fragments. This is corroborated by reactivity studies, which show that the hydrides are always retained at the iridium sites and that the [Cp*IrH 3 ] - moieties are labile and can be transmetalated to yield potassium ([KIrCp*H 3 ], 8 ) or silver (([AgIrCp*H 3 ] n , 10 ) derivatives of potential synthetic interest. DFT calculations show that the bonding situation can vary in these systems, from 3-center 2-electron hydride-bridged Lewis adducts of the form Ir-H⇀Al to direct polarized metal-metal interaction from donation of d -electrons of Ir to the Al metal, and both types of interactions take place to some extent in each of these clusters.

We report the synthesis of C 3 -symmetric cryptophanes decorated with three aromatic amine groups on the same CTB cap and their interaction with xenon. The relative stereochemistry of these two stereoisomers syn and anti was assessed thanks to the determination of the X-ray structure of an intermediate compound. As previously observed with the tris-aza-cryptophanes analogs anti - 1 and syn - 2 ( J. Org. Chem . 2021 , 86 , 11, 7648-7658), both compounds anti - 5 and syn - 6 show a slow in-out exchange dynamics of xenon at 11.7 T. Our work supports the idea that the presence of nitrogen atoms grafted directly onto the cryptophane backbone has a strong impact on the in-out exchange dynamics of xenon whatever their stereochemistry. This result contrasts with the case of other cryptophanes decorated solely with methoxy substituents. Finally, we demonstrate that these new derivatives can be used to design new anti / syn cryptophanes bearing suitable ligands in order to constitute potent 129 Xe NMR-based sensors. An example is reported here with the synthesis of the tris-iodo derivatives anti - 13 and syn - 14 from compounds anti - 5 and syn - 6 .

Vector-borne diseases cause around 700,000 deaths every year. Insect repellents are one of the strategies to limit them. Para -menthane-3,8-diol (PMD), a natural compound, is one of the most promising alternatives to conventional synthetic repellents. This work describes a diastereodivergent method to synthesize each diastereoisomer of PMD from enantiopure citronellal and studies their repellence activity against Aedes albopictus . We found that cis -PMD is the kinetic control product of the cyclization of citronellal, while trans -PMD is the thermodynamic control product. X-ray diffraction analysis of crystals highlighted some differences in hydrogen-bond patterns between cis or trans isomers. The present paper demonstrates that (1 R )-(+)- cis -PMD has the highest repellency index using a new evaluation system for 24 h. (1 S )-(-)- cis -PMD has somewhat lower and (1 S )-(+)- trans -PMD and (1 R )-(-)- trans -PMD have a slight effect. Volunteer tests show that (1 R )-(+)- cis -PMD is the most efficient. This effect could be ascribed to the interaction of PMD/insect odorant receptors and their physical properties, that is, the evaporation rate.

The iridium tetrahydride complex Cp*IrH 4 reacts with a range of isobutylaluminum derivatives of general formula Al( i Bu) x (OAr) 3- x ( x = 1, 2) to give the unusual iridium aluminum species [Cp*IrH 3 Al( i Bu)(OAr)] ( 1 ) via a reductive elimination route. The Lewis acidity of the Al atom in complex 1 is confirmed by the coordination of pyridine, leading to the adduct [Cp*IrH 3 Al( i Bu)(OAr)(Py)] ( 2 ). Spectroscopic, crystallographic, and computational data support the description of these heterobimetallic complexes 1 and 2 as featuring strongly polarized Al(III) δ+ -Ir(III) δ- interactions. Reactivity studies demonstrate that the binding of a Lewis base to Al does not quench the reactivity of the Ir-Al motif and that both species 1 and 2 promote the cooperative reductive cleavage of a range of heteroallenes. Specifically, complex 2 promotes the decarbonylation of CO 2 and AdNCO, leading to CO (trapped as Cp*IrH 2 (CO)) and the alkylaluminum oxo ([( i Bu)(OAr)Al(Py)] 2 (μ-O) ( 3 )) and ureate ({Al(OAr)( i Bu)[κ 2 -(N,O)AdNC(O)NHAd]} ( 4 )) species, respectively. The bridged amidinate species Cp*IrH 2 (μ-CyNC(H)NCy)Al( i Bu)(OAr) ( 5 ) is formed in the reaction of 2 with dicyclohexylcarbodiimine. Mechanistic investigations via DFT support cooperative heterobimetallic bond activation processes.

The identification of reactive intermediates during molecule-to-nanoparticle (NP) transformation has great significance in comprehending the mechanism of NP formation and, therefore, optimizing the synthetic conditions and properties of the formed products. We report here the room temperature (RT) synthesis of AgCuSe NPs from the reaction of di- tert -butyl selenide with trifluoroacetates (TFA) of silver(I) and copper(II). The isolation and characterization of a molecular species during the course of this reaction, [Ag 2 Cu(TFA) 4 ( t Bu 2 Se) 4 ] ( 1 ), which shows extraordinary reactivity and interesting thermochromic behavior (blue at 0 °C and green at RT), confirmed that ternary metal selenide NPs are formed via this intermediate species. Similar reactions with related dialkyl chalcogenide R 2 E resulted in the isolation of molecular species of similar composition, [Ag 2 Cu(TFA) 4 (R 2 E) 4 ] [R = t Bu, E = S ( 2 ); R = Me, E = Se ( 3 ); R = Me, E = S ( 4 )], which are stable at RT but can be converted to ternary metal chalcogenides at elevated temperature. Density functional theory calculations confirm the kinetic instability of 1 and throw light on its thermochromic properties.

A series of asymmetric and potentially bidentate amino alcohols and amino fluoro alcohols (R N OH) having a different number of methyl/trifluoromethyl substituents at the α-carbon atom, [HOC(R 1 )(R 2 )CH 2 NMe 2 ] (R 1 = R 2 = H (dmaeH); R 1 = H, R 2 = CH 3 (dmapH); R 1 = R 2 = CH 3 (dmampH); R 1 = H, R 2 = CF 3 (F-dmapH); R 1 = R 2 = CF 3 (F-dmampH)) have been used to develop new monomeric and heteroleptic tin(IV) amino(fluoro)alkoxides [Sn(OR) 2 (OR N ) 2 ] (R = Et, Pr i , Bu t ). These new complexes, which were thoroughly characterized by spectroscopy (IR and multinuclei NMR ( 1 H, 13 C, 19 F, and 119 Sn)) as well as single-crystal X-ray studies on representative samples, were investigated for their thermal behavior to determine their suitability as MOCVD precursors for the deposition of metal oxide thin films. The two most suitable compounds, [Sn(OBu t ) 2 (dmamp) 2 ] and [Sn(OBu t ) 2 (F-dmamp) 2 ], were used in a direct liquid injection chemical vapor deposition (DLI-CVD) process to deposit undoped SnO 2 and F-doped SnO 2 thin films, respectively, on silicon and quartz substrates. Film growth rates at different temperatures (from 400 to 700 °C), film thickness, crystalline quality, and surface morphology were investigated. The films deposited on quartz showed high transparency (above 80%) in the visible region and low carbon contamination on the surface (11-13% from XPS), which could easily be removed completely with 2 min of Ar + sputtering.

We describe a large-scale synthesis of a series of helicene-like compounds based on a dibenzo[ c ]acridine fragment by the Friedlander reaction. The series includes targeted constrained (closed) derivatives comprising 11 rings that exhibit very intense circularly polarized luminescence (CPL) ( g lum = 8 × 10 -3 ) contrary to their nonconstrained (open) 10-ring precursors that are not CPL active. The relationship between structure and chiroptical properties in the series is discussed with the aid of quantum-chemical calculations.

In the context of molecular engineering of push-pull dipolar dyes, we introduce a structural modification of the well-known electron-accepting group 2-dicyanomethylidene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran ( TCF ). Introduction of a (benzo[ d ]thiazol-2-yl) moiety failed, and unexpected structures were obtained. On the other hand, phenylthio and phenylsulfonyl entities were successfully introduced at position 3 of the 2-(dicyanomethylidene)-2,5-dihydrofuran ring, giving access to new electron-acceptor groups and dipolar fluorophores displaying near-infrared emission in solution or in the solid state, brighter than their TCF analogues.

In this article, we present the synthesis of new cryptophane-type hosts capable of binding xenon in aqueous media and that may be useful for the development of xenon-based magnetic resonance imaging derivatives. The synthetic route proposed was chosen to facilitate both the introduction of water-solubilizing substituents and the functionalization of the host with a single arm showing recognition properties that constitute two crucial steps. This was made possible by preparing new cryptophane-223 derivatives bearing two different chemical functions that can be easily modified at a later stage. Thus, subsequent reactions allowed the design of a new cryptophane host able to bind zinc or nickel cations. The ability of this molecule to bind cationic species was assessed by calorimetric titration experiments and hyperpolarized 129 Xe NMR. The advantages and disadvantages of this approach are discussed.

Whereas the synthesis of the anti-cryptophane-A (1) derivative has been known for nearly 40 years, the preparation of its diastereomer (cryptophane-B according to Collet's nomenclature) has never been reported. Thus, the synthesis of the cryptophane-B derivative represents a real challenge for chemists interested in the preparation of these hollow molecules. Herein, we describe a synthetic route that allows us to prepare cryptophane-B (2), albeit in a low yield. The X-ray crystallographic structure of this compound is described, and it reveals the presence of an ethanol molecule inside the cavity of the host. Finally, the ability of cryptophane-B to bind xenon in 1,1,2,2-tetrachloroethane- d 2 is also studied via hyperpolarized 129 Xe NMR.

The use of the dialkene divinyltetramethyldisiloxane (dvtms) allows easy access to the reactive 16 valence-electron complexes [Fe 0 (L-L)(dvtms)], (L-L) = dppe (1,2-bis(diphenylphosphino)ethane), ( 1 ), dppp (1,2-bis(diisopropylphosphino)propane), ( 2 ), pyNMeP( i Pr) 2 (N-(diisopropylphosphino)-N-methylpyridin-2-amine), ( 4 ), dipe (1,2-bis(diisopropylphosphino)ethane), ( 5 ), and [Fe 0 (L) 2 (dvtms)], L = PMe 3 , ( 3 ), by a mild reductive route using AlEt 2 (OEt) as reducing agent. In contrast, by the same methodology, the 18 valence-electron complexes [Fe 0 (L-L) 2 (ethylene)], (L-L) = dppm (1,2-bis(diphenylphosphino)methane), 6 , (L-L) = dppa (1,2-bis(diphenylphosphino)amine) 7 or (L-L)=dppe, 8 , were obtained, which do not contain dvtms. In addition, a combined DFT and solid-state paramagnetic NMR methodology is introduced for the structure determination of 5 . A comparative study of the reactivity of 1 , 2 , 4 - 6 and 8 with 3-hexyne highlights emerging mechanistic implications for C-C coupling reactions using these complexes as catalysts., Competing Interests: The authors declare no competing financial interest.

Enantiopure cryptophane derivatives 1 and 2, possessing linkers of different nature (ethylenedioxy and propylenedioxy) connecting the two cyclotribenzylenes (CTB) units, were separated by HPLC using chiral stationary phases. X-ray crystallographic structures of the four enantiomers (+)-1, (-)-1, (+)-2, and (-)-2 have been obtained, allowing the unambiguous determination of their absolute configuration (AC) in the solid state. The chiroptical properties of compounds 1 and 2 were determined from polarimetry, electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) experiments and were compared to those of cryptophane-A (3) derivative. VCD, ROA and ECD spectra of 1 and 2 were calculated by density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations, respectively, to confirm the AC of the cryptophane derivatives in solution. The (+)-PP and (-)-MM configurations were established for compounds 1 and 2 in chloroform solution, as already reported for the two enantiomers of 3. This result is in agreement with the X-ray structures of the two enantiomers of 1 and 2.

New barium-organic derivatives are introduced as countercations in the iodocuprates and -argentates to yield novel hybrids with unique structural motifs and bonding modes, many of them also showing vivid fluorescence on exposure to UV light. The tetrahedral MX4/trigonal-coplanar MX3 unit in these hybrids [Ba2(DMSO)12Cu8I12] (1) and [Ba(tetraglyme)2]2[Ag8I12]·EtOH (7) can be replaced by the M'I4/M'I3 unit without compromising their basic structural motifs, thus leading to the formation of the rare mixed Cu-Ag iodometalates [Ba2(DMSO)12Cu4Ag4I12] (9) and [Ba(tetraglyme)2]2[CuAg7I12]·EtOH (10), respectively. In contrast, a breakdown in the structure-directing properties of these iodometalates was observed in the mixed Ag-Pb iodometalate [Ba(tetraglyme)2]2[Pb2Ag2I10]·2Me2CO (11), where the basic structure of the synthon [Ba(tetraglyme)2]2[Ag4I8] (8) was not retained due to the compulsory molecular rearrangement required as a result of replacing AgI4/AgI3 units with octahedral PbI6 units.

The octupolar cube, a Td symmetry cube presenting alternating charges at its corners, is the generic point charge template of any octupolar molecule. So far, transposition into real molecular structures has yet to be achieved. We report here a first step toward the elaboration of fully cubic octupolar architectures. A series of octupolar bis(2,3,16,17-tetra(hexylthio)phthalocyaninato)lanthanide double-decker complexes [Pc2Ln], Ln = Nd (1), Eu (2), Dy (3), Y (4), and Lu (5), are described, whose original three-dimensional structures display the required alternation of ABAB type for one face of the cube and the delocalization between the two rings approximating to the electronic interaction along the edges of the cube. Synthesis, X-ray crystal structure, and study of the optical properties and of the first molecular hyperpolarizability β are reported. The size of the lanthanide (III) central ion modulates the ring-to-ring distance and the degree of coupling between the two phthalocyanine rings. As a consequence, the optical properties of these octupolar chromophores and in particular the strong near-infrared absorption due to the intervalence transition between the two rings also depend on the central lanthanide (III) ion. The first oxidized and reduced states of the complexes, while keeping a similar octupolar structure, display considerably changed optical properties compared to the neutral states. Second-order nonlinear properties were determined by nonpolarized harmonic light scattering in solution at 1907 nm. Exceptionally large dynamic molecular first hyperpolarizabilities √(<βHLS(2)>1907), among the highest ever reported, were found that showed a strong dependence on the number of 4f electrons.

In this paper, we report the synthesis and description of a new family of polynuclear cobalt(II) complexes. Starting from the same initial compounds but varying the reaction time results in the formation of several new clusters, an original structure based on [Co14][Co4] clusters was obtained, representing the first one-pot synthesis of a cobalt aggregate salt reported in the literature. The synthesis and magnetic properties of these cobalt compounds are discussed. Three of them display a binuclear molecular structure (1-3) with two encapsulated Co(II) ions and show slow relaxation of magnetization at small applied magnetic field (Ueff = 10.7 K for 2 and Ueff = 20.3 K for 3), a characteristic of single-molecule-magnet materials.

Endohedral functionalization of the molecular cavity of host molecules is in high demand in many areas of supramolecular chemistry. When highly reactive species are incarcerated in the confined space of a molecular cavity, deep changes of their chemical properties are expected. Here, we show that the superbasic properties of proazaphosphatranes can be improved in the confined space of the molecular cavity of hemicryptophane hosts. A general and modular procedure is described to prepare supramolecular superbases with various cavity sizes. The rate of proton transfer is strongly dependent on the shape and size of the inner cavity of the designed superbasic structure. Kinetic and thermodynamic data are strongly correlated to the space available around the basic center as revealed by the X-ray molecular structures analyses.

A new type of dinuclear iridium complex, based on a quadrupolar Schiff base ligand, is synthesized and its structure fully characterized. Its linear and nonlinear spectroscopic properties are investigated, evidencing a strong contribution of the metal-to-ligand transitions not only to the linear absorption but also to the two- and three-photon absorption properties.

Reaction in ethanol of 3-hydroxymethylen-5-methylsalicylaldoxime (H3L) with CuCl2·2H2O and LnCl3·xH2O [Ln = La (1), Ce (2), Pr (3), Nd (4), Eu (5), Gd (6), Tb (7), Dy (8), Er (9), Yb (10), Lu (11), Ho (12)] allowed the synthesis of a family of hendecanuclear heterometallic copper(II)-lanthanide(III) clusters with general formula [Ln(III)3Cu(II)8(HL)6(μ4-O)2Cl6(H2O)8]Cl3 (1-12). According to the single-crystal X-ray diffraction investigation, the complexes are isomorphous and crystallize in the trigonal R32 group. The hendecanuclear cluster is formed by two tetrahedral μ4-oxo {Cu4} clusters assembled by three lanthanide ions sandwiched in between. Along the family, the separation between the {Cu4} moieties increases linearly from Lu to La in good correlation with ionic radius of the lanthanide ions. A comparative analysis of the magnetic data for the lanthanum (1) and lutetium (11) compounds shows the presence of ferromagnetic and antiferromagnetic interactions within the μ4-oxo {Cu4} moieties. For the gadolinium (6) and terbium (7) compounds, the magnetic interactions between the lanthanide and the copper ions are found to be ferromagnetic. The dysprosium (8) compound exhibits single-molecule magnet behavior.

We report the synthesis of new cryptophane derivatives 1-4 bearing nine (1, 2) and twelve (3, 4) methoxy substituents. These compounds represent the first examples of cryptophane derivatives bearing more than six substituents attached on the benzene rings. The preparation of these highly substituted cryptophanes was achieved due to the synthesis of a new cyclotrisyringyl derivative obtained from the reaction of a protected syringyl alcohol in the presence of a catalytic amount of scandium triflate Sc(OTf)3. This reaction also provides the protected cyclotetrasyringyl derivative in low yield (7%), which was fully characterized by (1)H NMR, IR, and X-ray crystallography. In contrast to what is observed for the cryptophane-A congener, the synthesis of these highly substituted cryptophanes gives rise to the two anti- and syn-diastereomers. These compounds have been fully characterized, and their X-ray structures have been obtained to ascertain the stereochemistry of these new cryptophane derivatives.

Synthesis and X-ray diffraction structures of cis and trans isomers of ruthenium and osmium metal complexes of general formulas (nBu4N)[cis-MCl4(NO)(Hind)], where M = Ru (1) and Os (3), and (nBu4N)[trans-MCl4(NO)(Hind)], where M = Ru (2) and Os (4) and Hind = 1H-indazole are reported. Interconversion between cis and trans isomers at high temperatures (80-130 °C) has been observed and studied by NMR spectroscopy. Kinetic data indicate that isomerizations correspond to reversible first order reactions. The rates of isomerization reactions even at 110 °C are very low with rate constants of 10(-5) s(-1) and 10(-6) s(-1) for ruthenium and osmium complexes, respectively, and the estimated rate constants of isomerization at room temperature are of ca. 10(-10) s(-1). The activation parameters, which have been obtained from fitting the reaction rates at different temperatures to the Eyring equation for ruthenium [ΔH(cis-trans)‡ = 122.8 ± 1.3; ΔH(trans-cis)‡ = 138.8 ± 1.0 kJ/mol; ΔS(cis-trans)‡ = -18.7 ± 3.6; ΔS(trans-cis)‡ = 31.8 ± 2.7 J/(mol·K)] and osmium [ΔH(cis-trans)‡ = 200.7 ± 0.7; ΔH(trans-cis)‡ = 168.2 ± 0.6 kJ/mol; ΔS(cis-trans)‡ = 142.7 ± 8.9; ΔS(trans-cis)‡ = 85.9 ± 3.9 J/(mol·K)] reflect the inertness of these systems. The entropy of activation for the osmium complexes is highly positive and suggests the dissociative mechanism of isomerization. In the case of ruthenium, the activation entropy for the cis to trans isomerization is negative [-18.6 J/(mol·K)], while being positive [31.0 J/(mol·K)] for the trans to cis conversion. The thermodynamic parameters for cis to trans isomerization of [RuCl4(NO)(Hind)]-, viz. ΔH° = 13.5 ± 1.5 kJ/mol and ΔS° = -5.2 ± 3.4 J/(mol·K) indicate the low difference between the energies of cis and trans isomers. The theoretical calculation has been carried out on isomerization of ruthenium complexes with DFT methods. The dissociative, associative, and intramolecular twist isomerization mechanisms have been considered. The value for the activation energy found for the dissociative mechanism is in good agreement with experimental activation enthalpy. Electrochemical investigation provides further evidence for higher reactivity of ruthenium complexes compared to that of osmium counterparts and shows that intramolecular electron transfer reactions do not affect the isomerization process. A dissociative mechanism of cis↔trans isomerization has been proposed for both ruthenium and osmium complexes.

Ruthenium nitrosyl complexes of the general formulas (cation)(+)[cis-RuCl4(NO)(Hazole)](-), where (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (Hind) (1c), (cation)(+) = (H2pz)(+), Hazole = 1H-pyrazole (Hpz) (2c), (cation)(+) = (H2bzim)(+), Hazole = 1H-benzimidazole (Hbzim) (3c), (cation)(+) = (H2im)(+), Hazole = 1H-imidazole (Him) (4c) and (cation)(+)[trans-RuCl4(NO)(Hazole)](-), where (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (1t), (cation)(+) = (H2pz)(+), Hazole = 1H-pyrazole (2t), as well as osmium analogues of the general formulas (cation)(+)[cis-OsCl4(NO)(Hazole)](-), where (cation)(+) = (n-Bu4N)(+), Hazole =1H-indazole (5c), 1H-pyrazole (6c), 1H-benzimidazole (7c), 1H-imidazole (8c), (cation)(+) = Na(+); Hazole =1H-indazole (9c), 1H-benzimidazole (10c), (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (11c), (cation)(+) = H2pz(+), Hazole = 1H-pyrazole (12c), (cation)(+) = (H2im)(+), Hazole = 1H-imidazole (13c), and (cation)(+)[trans-OsCl4(NO)(Hazole)](-), where (cation)(+) = n-Bu4N(+), Hazole = 1H-indazole (5t), 1H-pyrazole (6t), (cation)(+) = Na(+), Hazole = 1H-indazole (9t), (cation)(+) = (H2ind)(+), Hazole = 1H-indazole (11t), (cation)(+) = (H2pz)(+), Hazole = 1H-pyrazole (12t), have been synthesized. The compounds have been comprehensively characterized by elemental analysis, ESI mass spectrometry, spectroscopic techniques (IR, UV-vis, 1D and 2D NMR) and X-ray crystallography (1c·CHCl3, 1t·CHCl3, 2t, 3c, 6c, 6t, 8c). The antiproliferative activity of water-soluble compounds (1c, 1t, 3c, 4c and 9c, 9t, 10c, 11c, 11t, 12c, 12t, 13c) in the human cancer cell lines A549 (nonsmall cell lung carcinoma), CH1 (ovarian carcinoma), and SW480 (colon adenocarcinoma) has been assayed. The effects of metal (Ru vs Os), cis/trans isomerism, and azole heterocycle identity on cytotoxic potency and cell line selectivity have been elucidated. Ruthenium complexes (1c, 1t, 3c, and 4c) yielded IC50 values in the low micromolar concentration range. In contrast to most pairs of analogous ruthenium and osmium complexes known, they turned out to be considerably more cytotoxic than chemically related osmium complexes (9c, 9t, 10c, 11c, 11t, 12c, 12t, 13c). The IC50 values of Os/Ru homologs differ by factors (Os/Ru) of up to ~110 and ~410 in CH1 and SW480 cells, respectively. ESI-MS studies revealed that ascorbic acid may activate the ruthenium complexes leading to hydrolysis of one M-Cl bond, whereas the osmium analogues tend to be inert. The interaction with myoglobin suggests nonselective adduct formation; i.e., proteins may act as carriers for these compounds.

The concept of octupolar molecules has considerably enlarged the engineering of second-order nonlinear optical materials by giving access to 2D and 3D architectures. However, if the archetype of octupolar symmetry is a cube with alternating donor and acceptor groups at the corners, no translation of this ideal structure into a real molecule has been realized to date. This may be achieved by designing a bis(phthalocyaninato)lutetium(III) double-decker complex with a crosswise ABAB phthalocyanine bearing alternating electron-donor and electron-acceptor groups. In this communication, we present the first step toward this goal with the synthesis, crystal structure determination, and measurement of the molecular first-order hyperpolarizability β by harmonic light diffusion, of an original lutetium(III) sandwich complex displaying the required ABAB-type alternation for one face of the cube. This structure is characterized by an intense absorption in the near-IR due to an intervalence transition and exhibits the highest quadratic hyperpolarizability ever reported for an octupolar molecule, √<β(2)(HLS)> = 5750 × 10(-30) esu., (© 2012 American Chemical Society)

Two benzoxazoles derivative ligands were synthesized from the condensation of 3,5-di-tert-butyl-o-benzoquinone (DTBBQ) with ethanolamine or 1,3-diamino-2-hydroxypropane in methanol. Condensation of DTBBQ with ethanolamine gives the expected 5,7-di-tert-butyl-2-methylenhydroxylbenzoxazole (HL1) while with 1,3-diamino-2-hydroxypropane it gives (2-hydroxyethyl-2-{2,4-bis(1,1-dimethylethyl)-1-phenol-6 amino}-2{5,7-di-tert-butyl-benzoxazole}) (H(2)L2) with only one benzoxazole ring instead of the symmetric bis-benzoxazole derivative. The structure of HL1 and H(2)L2 were confirmed by NMR-spectroscopy and X-ray diffraction on a single crystal for HL1. The reaction of HL1 with CuCl(2) gives a mononuclear [Cu(II)(HL1)(2)Cl(2)] (1) complex for which the crystal structure shows that HL1 is preserved. In contrast, upon reaction with nickel(II), cobalt(II), and manganese(II) H(2)L2 is further oxidized and transformed in new ligands HL3 in mononuclear complexes [M(II)(L3)(2)] (M = Ni(II) (2); M = Co(II) (3)) and H(2)L4 in tetranuclear complex [Mn(II)(4)(HL4)(4)Cl(4)] (4) as found from the crystal structures of complexes 2-4. Electrochemical studies for complexes 2 and 3 evidence complicated redox properties. [Mn(II)(4)(HL4)(4)Cl(4)] (4) has a cubane-like structure with a "4 + 2" fashion The magnetic susceptibility of 4 is well fitted considering one Mn---Mn interaction J(a)(Mn(II)-Mn(II)) = -0.50(1) cm(-1) with g = 2.00(7).

Three Cu-Ln (Ln = Dy, Gd, Y) dodecanuclear clusters assembled by a novel ligand of the benzoxazole type are reported. The dysprosium cluster exhibits a frequency dependence of the alternating-current susceptibility and hysteresis loop at low temperature, indicating single-molecule-magnet behavior., (© 2011 American Chemical Society)

The nanometric mixed tin-titanium oxide doped with a M(5+) cation was recently shown as a promising thermoelectric material. We report here synthesis of novel molecular precursors for above material using a convenient approach of reacting a metal chloride with a metal alkoxide. Heterometallic complexes with simple addition formula [(EtOH)(2)(OEt)(2)Ti(μ-OEt)(2)SnCl(4)] (1·EtOH) and [(EtOH)(OEt)(3)Ta(μ-OEt)(2)SnCl(4)] (2) were isolated in quantitative yield, which on recrystallization from isopropanol afforded mixed-alkoxide complexes [(Pr(i)OH)(2)(OPr(i))(2)Ti(μ-OEt)(2)SnCl(4)] (3) and [(Pr(i)OH)(OPr(i))(3)Ta(μ-OEt)(2)SnCl(4)] (4), respectively, thus indicating the robustness of the heterometallic M(μ-OEt)(2)Sn core in the solution phase. Facile conversion of these precursors to halide-free spinodal form of Ta(5+)-doped TiO(2)-SnO(2) as a potential thermoelectric material is reported.

The preparation of a new trisodium triborate, Na(3)[B(3)O(4)(OH)(4)], and its complete characterization in terms of molecular structure and thermal behavior are reported. Synthesis of this compound was achieved either by NaBH(4) hydrolysis or by thermal treatment of Na[B(OH)(4)].2H(2)O. The crystal structure was determined by single-crystal X-ray diffraction. The trisodium triborate crystallized in the monoclinic system (a = 12.8274(6) A, b = 7.7276(4) A, c = 6.9690(3) A, and beta = 98.161(3) degrees ), space group Cc, Z = 2. The structure of Na(3)[B(3)O(4)(OH)(4)] comprised [B(3)O(4)(OH)(4)](3-) polyanions, based on B-O-containing rings with two tetracoordinated boron atoms and one tricoordinated boron atom in the fragments BO(2)(OH)(2) and BO(3), respectively. These polyanions are interconnected by four intermolecular hydrogen bonds and presented a tilt of 10.470(4) degrees compared to the a axis. Thus, they are stacked by rotation of about 180 degrees around an axis defined by the three-coordinated boron atoms and parallel to the c axis. Such polyanions were only observed previously in two synthetic compounds, M(3)[B(3)O(4)(OH)(4)].2H(2)O with M = K and Rb, which were isostructural. The originality of the present work was the synthesis and the description of a different crystallographic structure containing this polyanion. Characteristic peaks ranging from 500 to 1500 cm(-1) and around 3300 cm(-1) highlighted the presence of the B-O rings and hydroxyl groups, respectively. The decomposition temperature T = 155 degrees C was obtained by thermogravimetric analysis, and the following equivalent formula in terms of hydration degree was proposed: NaBO(2).(2)/(3)H(2)O. Na(3)[B(3)O(4)(OH)(4)] decomposed into Na(3)[B(3)O(5)(OH)(2)] in equilibrium with its vapor.

This study deals with the development of a soft, generic, one-pot postfunctionalization method for metal-organic frameworks (MOFs) starting from compounds with an amino group on the linker. The first step consists of transforming the amino group into azide (N(3)) by an unconventional route using tBuONO and TMSN(3). In the same vessel, the desired functionalized MOF then is obtained by the Huisgen 1,3-dipolar cycloaddition of azides to alkynes, otherwise known as the "click" reaction. The method was applied to DMOF-NH(2) and MIL-68(In)-NH(2), which represent two distinct and important classes of MOF. For both, the functionalization was complete (>90% grafting) and the crystallinity was maintained. Thanks to the large diversity and availability of cyano- and acetylene-based chemicals, this method opens the door to tailor-made functionalized MOFs.

Solvated yttrium iodide precursors [Y(L)8]I3 [L = dimethylformamide (DMF) or dimethylsulfoxide (DMSO)], prepared in situ by stirring YI3(Pr(i)OH)4 in DMF/DMSO, react with 3 equiv of PbI2 in the presence of NH4I to give novel hybrid derivatives based on either a one-dimensional (1D) straight chain, [Y(DMF)8][Pb3(mu-I)9](1infinity) x DMF (1), or discrete pentanuclear iodoplumbates, [Y(DMSO)8]2[(DMSO)2Pb5(mu3-I)2(mu-I)8I6] (2a). The complex 2a and a closely related [Y(DMSO)8][Y(DMSO)7(DMF)][(DMSO)2Pb5(mu3-I)2(mu-I)8I6] (2b) were obtained in good yield by solution phase transformation of 1 in DMSO under slight different conditions. Derivatives 1 and 2 also undergo unique solid-state transformation in a confined environment of paratone to give 1D polymers based on zigzag iodoplumbate chains; crystals of 1 transform into [Y(DMF)6(H2O)2][Pb3(mu3-I)(mu-I)7I](1infinity) (3) via an exchange reaction, whereas those of 2a and 2b are converted into [Y(DMSO)7][Pb3(mu3-I)(mu-I)7I](1infinity) (4) via a decomposition pathway. The trifurcate H-bonding between water ligands on yttrium cation and iodide of the iodoplumbate anion plays a pivotal role in transforming the straight 1D polymeric Pb-I chain of 1 into a zigzag chain in 3. The thermogravimetry-differential thermal analysis studies indicate that complexes with DMF ligands are thermally more stable than those with DMSO ones, the mixed DMF-H2O ligand complex 3 being the most stable one because of the presence of strong H-bonding. Diffuse-reflectance UV-visible spectral analyses of 1-4 show an optical band gap in the 1.86-2.54 eV range, indicating these derivatives as potential semiconductors. In contrast to non-emissive 3 and 4, derivatives 1, 2a, and 2b show remarkable luminescent emission with peak maxima at 703 nm, assigned as an iodine 5p-lead 6s to lead 6p charge transfer (XM-M-CT).

In the presence of bases, trifluoroacetone is known to trimerize leading to configurationally labile 6-methyl-2,4,6-tris(trifluoromethyl)tetrahydro-2H-pyran-2,4-diols 1a,b and 2a,b, structurally close to fluorinated carbohydrates. We report herein a complete study of their behavior in solution. The remarkable solvent effect on the two equilibria (1a <--> 1b; 2a <--> 2b) was rationalized using solvent basicity measures and polarity scales. Solvents of weak donor number were found to favor the diastereoisomers 1a and 2a, which were subsequently isolated. According to their X-ray analyses, they both possess a concave structure with 1,3-cis-diaxial hydroxyl groups. A complementary kinetic study illustrated that acidic conditions can drastically reduce the equilibration rate, allowing the use of a wide range of solvents. Finally, a reexamination of previously published trimerization conditions using sodium or magnesium amalgam revealed that, contrary to the suggestion by two independent reports, 1,3,5-tris(trifluoromethyl)cyclohexane-1,3,5-triol 3/4 was neither formed as the principal product in place of 1a,b and 2a,b nor could it be detected as a minor product.

Deprotonation of benzoxazole, benzothiazole, benzo[b]thiophene, benzo[b]furan, N-Boc-protected indole and pyrrole, and N-phenylpyrazole using an in situ mixture of ZnCl(2).TMEDA (0.5 equiv) and lithium 2,2,6,6-tetramethylpiperidide (1.5 equiv) in THF at room temperature is described. The reaction was evidenced by trapping with iodine, regioselectively giving the expected functionalized derivatives in 52-73% yields. A mixture of mono- and disubstituted derivatives was obtained starting from thiazole. Cross-coupling reactions of 2-metalated benzo[b]thiophene and benzo[b]furan with heteroaromatic chlorides proved possible under palladium catalysis. A reaction pathway where the lithium amide and zinc diamide present in solution behave synergically was proposed for the deprotonation reaction, taking account of NMR and DFT studies carried out on the basic mixture.