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Triazene ligands are introduced, for the first time, in the precursor chemistry for their ability to afford oxygen-free molecular precursors of Fe0 nanoparticles. For this purpose, we synthesized new asymmetric triazene ligands t-BuNN-NHR (R = Et, i-Pr, n-Bu) featuring different alkyl substituents at 1,3-N centers, as well as a symmetric ligand t-BuNN-NHt-Bu and used them to develop novel heteroleptic monomeric FeII triazenide derivatives [Fe(t-BuN3R)2(TMEDA)] (where TMEDA = tetramethylethylenediamine). A range of physico-chemical studies such as FT-IR, TG-DTA, 1H & 13C NMR, mass spectrometry, single crystal X-ray structure analysis, cyclic voltammetry and Mossbauer spectroscopy were used to characterize these newly synthesized ligands and FeII derivatives. One representative derivative [Fe(t-BuN3Et)2(TMEDA)] was evaluated as a precursor for the synthesis of metallic Fe0 and intermetallic Al13Fe4 nanoparticles by the chemical solution deposition method.

RAMAN+CDFA+YIC:SMR:MDA:JZH:SDA; International audience; A novel single-source precursor NaGdACHTUNGTRENUNG(TFA)(4) ACHTUNGTRENUNG(diglyme) (TFA = trifluoroacetate) was synthesized, characterized thoroughly, and used to obtain the hexagonal phase of NaGdF4 nanoparticles as an efficient matrix for lanthanide-doped upconverting nanocrystals (NCs) that convert near-infrared radiation into shorter-wavelength UV/visible light. These NCs were then used to prepare well-characterized TiO2@NaGdF4:Yb3+, Tm3+ nanocomposites to extend the absorption range of the TiO2 photocatalyst from the UV to the IR region. While the visible/near IR part of the photoluminescent spectra remains almost unaffected by the presence of TiO2, the UV part is strongly quenched due to the absorption of TiO2 above its gap at approximately 380 nm by energy transfer or FRET. Preliminary results on the photocatalytic activity of the above obtained nanocomposites are presented.

The chemical preparation, crystal structure and spectroscopic characterization of [C 9 H 28 N 4 ][Bi 2 Cl 10 ].H 2 O have been reported. This compound crystallizes in the monoclinic system in space group P21/c and cell parameters a = 12.2385 (6), b = 17.3062 (7), c = 13.0772 (6) A, β = 104.475 (5)°, Z = 4 and V = 2681.9 (2) A 3 . Its crystal structure has been determined and refined to R = 0.049, using 5848 independent reflections. The atomic arrangement can be described by an alternation of organic and inorganic layers. The inorganic layer built up of [Bi 2 Cl 10 ] 4– bioctahedra arranged in sandwich between the organic layer. The organic groups are interconnected by the water molecules through N-H…O(W) hydrogen bonds to form infinite zig-zag chains spreading along the b -axis. These Chains are themselves interconnected by means of the N–H…Cl hydrogen bonds originating from [Bi 2 Cl 10 ] 4– anions, to form a three-dimensional network. Intermolecular Cl…Cl interactions between adjacent dimeric [Bi 2 Cl 10 ] 4– anions have been observed . The compound was also characterized by FT-IR and Raman spectrscopies.

The octupolar cube, a T-d 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 [Pc(2)Ln], 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 beta 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 root (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 CoII 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.

International audience; A simple method for thiacalix[4]arene O-monoamide preparation with high yields using 5,11,17,23-tetra-tert-butyl-28-(ethoxycarbonyl)methoxy-2,8,14,20-tetrathiacalix[4]arene reaction with diaminoalkanes is reported. The solid state cyclization reaction of the acylethylenediamines function of 5,11,17,23-tetra-tert-butyl-28-O-[(N-(2-aminoethyl)aminocarbonyl)-methoxy]thiacalix[4]arene leading to the formation of the 5,11,17,23-tetra-tert-butyl-28-[2-methoxy-imdazoline]thiacalix[4]arene compound is described for the first time for the calixarene macrocycle family. Finally, preliminary results show that O-mono-amide-thiacalixarene derivatives are promising candidates for the production of self-assembled materials and efficient precursors for the synthesis of bisthiacalix[4] arenes.; Nous reportons la préparation de dérivés O-monoamide thiacalixarènes obtenus à partir de la réaction entre le 5,11,17,23-tetra-tert-butyl-28-(ethoxycarbonyl)methoxy-2,8,14,20-tetrathiacalix[4]arene et différents diamino-alcanes. La réaction, à l’état solide, de cyclisation de la fonction acyléthylènediamine du composé 5,11,17,23-tetra-tert-butyl-28-O-[(N-(2-aminoethyl)aminocarbonyl)-methoxy]thiacalix[4]arene conduisant au composé 5,11,17,23-tetra-tert-butyl-25-[2-imdazoline-methoxy]thiacalix[4]arene est décrite pour la première fois pour la famille des macrocycles calixarèniques. Enfin, des réactions préliminaires attestent que les dérivés O-monoamide-thiacalixarènes sont de bons candidats pour l’obtention de matériaux auto-assemblés ainsi que de bons précurseurs pour la synthèse de bisthiacalix[4]arènes.

International audience; A bicyclic ligand platform for iron(II), which allows total control over the complex’s magnetic properties in aqueous solution simply by varying one of the six coordination sites of the bispidine ligand, is reported. To achieve this, an efficient synthetic route to an N5 bispidine framework (ligand L4) that features an unsubstituted N-7 site is established. Then, by choosing appropriate N-7-coordinating substituents, the spin state of choice can be imposed on the corresponding ferrous complexes under environmentally relevant conditions in water and near-room temperature. Importantly, the first low-spin and diamagnetic iron(II) chelates in the bispidine series, both in the solid state and in aqueous solution, are reported. The eradication of head-on steric clashes between pendent coordinating arms is at the origin of this success. A new pair of constitutionally similar ferrous coordination compounds of a multidentate ligand system is obtained, which exhibits a distinctly binary (off–on) magnetic relationship. The new synthetic intermediate L4 may be substituted in just one step by any desired pendent arm, thus allowing access to complexes with finely tuned magnetic properties.

The crystal structure of {aquaimidazole[2-(2-carbamoylhydrazone)-propionato]}copper(II) nitrate [Cu(L)Im(H2O)]NO3 (I), where HL is the semicarbazone of pyruvic acid, Im is imidazole, is dtermined. The crystal structure of I contains two independent complexes IA and IB in which copper atoms coordinate once deprotonated tridentate HL, imidazole, and water molecules. Outer spheres of the complexes contain nitrate ions. In the compounds studied the coordination polyhedron of the copper atom is a distorted tetragonal pyramid. Its base is composed of carboxyl and carbamide oxygen atoms, azomethine nitrogen of monodeprotonated HL molecules, and the imidazole nitrogen atom. In the crystal, nitrate ions and imidazole molecules link the complexes via hydrogen bonds into 2D networks parallel to the (010) plane. These networks in turn are in pairs arranged into layers along the [010] direction due to hydrogen bonds between water molecules and oxygen atoms of nitrate ions, and also by water molecules and O3 atoms of the neighboring 2D networks. In the crystal, the π-π stacking interaction is observed between the imidazole rings from different layers and there is also a N-O…Cg (π ring) interaction inside the layers.

The title compound crystallized with two independent mol­ecules in the asymmetric unit. Each mol­ecule has three stereogenic centres with configurations 2(S), 3(S) and 4(R), confirmed by resonant scattering., The title compound, C15H18ClN5O2, crystallizes with two independent mol­ecules (A and B) in the asymmetric unit. In both mol­ecules, the isoxazolidine rings have an envelope conformation with the O atoms at the flap positions. Each mol­ecule has three stereogenic centres with configurations 2(S), 3(S) and 4(R), confirmed by resonant scattering. Their conformations are significantly different, for example in mol­ecule A the phenyl ring is inclined to the triazole ring by 32.5 (2)°, while in mol­ecule B the corresponding dihedral angle is 10.7 (2)°. In the crystal, the A and B mol­ecules are linked via an N—H⋯O and a C—H⋯O hydrogen bond. These units are linked by C—H⋯O and C—H⋯N hydrogen bonds, forming slabs parallel to the ab plane. There are C—H⋯π inter­actions present within the slabs.

SSCI-VIDE+CARE:CDFA+SMR:DDA:FDA:CGU:JZH:SDA; International audience; The reactions of different silver(I) reagents AgX (X- =iodide, trifluoroacetate, triflate) with selenoethers R2Se (R=Me, tBu) in a variety of solvents were investigated in relation with their use as precursors for Ag2Se nanomaterials. Different reaction conditions led to different reactivities and afforded either molecular complexes or metal selenide nanoparticles. The reactions leading to in situ formation of the metal selenide nanoparticles were then extended in the presence of commercial TiO2 (P25) to prepare silver selenide-titania nanocomposites with different Ag/Ti ratios. These nanocomposites, well characterized by elemental analysis (Ag, Se), PXRD, TEM, BET, XPS and UV/Vis studies, were investigated as photocatalysts for the degradation of formic acid (FA) solution. The xAg(2)Se-TiO2 nanocomposites (x=0.01, 0.13 and 0.25 mol%) exhibited a much higher catalytic activity as compared to P25, which is an established benchmark for the photocatalysis under UV light, and retained a good photocatalytic stability after recycling for several times.

Dyes emitting in the solid state in the red or near-infrared range are much sought after for application in bioimaging especially if the long emission wavelength can be combined with two-photon excitation to provide unique contrast and penetration depth. In this article we present a series of small push–pull dipolar fluorophores based on 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofurane as electron accepting group. Compounds 1a–1m differ only by the number (one, two or three) and the position of methoxy groups on the electron-donor part. If these compounds are weakly emissive in dilute solution, they exhibit aggregation-induced emission properties and exciting solid state emission in the red – near infrared range very different from one compound to another highlighting the role of the number and of the position of the methoxy electron-donor groups. The solid-state properties were studied by fluorescence spectroscopy and the solid state structures were analyzed by X-ray diffraction showing the presence of a long chain of specific aggregates for the emitting species. Finally, the two-photon excitation properties were measured over the range 780–920 nm directly on the solid.

The synthesis of a series of six new per-substituted p-tert-butylcalix[9]arenes derivatives has been achieved. Functions such as ester, nitrile, or carbonate have been grafted on the phenolic oxygens of calix[9]arene: p-tert-butylcalix[9]arene nona-ethyl acetate, p-tert-butylcalix[9]arene nona-carboxylic acid, p-tert-butylcalix[9]arene nona-cyanopropyloxy, p-tert-butylcalix[9]arene nona-tert-butoxycarbonyle, p-tert-butylcalix[9]arene nona-acetyl, and p-tert-butylcalix[9]arene nona-trifluoroacetyl have been obtained in good yields (from 48% to 78%) and fully characterized. The X-ray structures of p-tert-butylcalix[9]arene nona-tert-butoxycarbonyl and p-tert-butylcalix[9]arene nona-ethyl acetate have been determined. A dynamic NMR study has revealed the high conformational mobility of such structures, even at low temperature.

1,1,1-Trimethylhydrazinium iodide ([(CH(3))(3)N-NH(2)]I, 1) was reacted with a silver salt to form the corresponding nitrate ([(CH(3))(3)N-NH(2)][NO(3)], 2), perchlorate ([(CH(3))(3)N-NH(2)][ClO(4)], 3), azide ([(CH(3))(3)N-NH(2)][N(3)], 4), 5-amino-1H-tetrazolate ([(CH(3))(3)N-NH(2)][H(2)N-CN(4)], 5), and sulfate ([(CH(3))(3)N-NH(2)](2)[SO(4)]·2H(2)O, 6·2H(2)O) salts. The metathesis reaction of compound 6·2H(2)O with barium salts led to the formation of the corresponding picrate ([(CH(3))(3)N-NH(2)][(NO(2))(3)Ph-O], 7), dinitramide ([(CH(3))(3)N-NH(2)][N(NO(2))(2)], 8), 5-nitrotetrazolate ([(CH(3))(3)N-NH(2)][O(2)N-CN(4)], 9), and nitroformiate ([(CH(3))(3)N-NH(2)][C(NO(2))(3)], 10) salts. Compounds 1-10 were characterized by elemental analysis, mass spectrometry, infrared/Raman spectroscopy, and multinuclear NMR spectroscopy ((1)H, (13)C, and (15)N). Additionally, compounds 1, 6, and 7 were also characterized by low-temperature X-ray diffraction techniques (XRD). Ba(NH(4))(NT)(3) (NT=5-nitrotetrazole anion) was accidentally obtained during the synthesis of the 5-nitrotetrazole salt 9 and was also characterized by low-temperature XRD. Furthermore, the structure of the [(CH(3))(3)N-NH(2)](+) cation was optimized using the B3LYP method and used to calculate its vibrational frequencies, NBO charges, and electronic energy. Differential scanning calorimetry (DSC) was used to assess the thermal stabilities of salts 2-5 and 7-10, and the sensitivities of the materials towards classical stimuli were estimated by submitting the compounds to standard (BAM) tests. Lastly, we computed the performance parameters (detonation pressures/velocities and specific impulses) and the decomposition gases of compounds 2-5 and 7-10 and those of their oxygen-balanced mixtures with an oxidizer.

1,3-Dipolar cycloaddition of a chiral nitrone derived from (−)-menthone to ( E )-1,4-dichlorobut-2-ene was the key step in a novel 5 step synthesis of (2 S ,3 S ,4 R )-4-hydroxyisoleucine, obtained in 21% overall yield with high enantiopurity.

Oxidation of 1,1-dimethylhydrazine leads to the formation of (E)-1,1,4,4-tetramethyl-2-tetrazene (1). Compound 1 undergoes oxidative addition with chloramine (Cl–NH2) to form the (E)-1-aminomethylidene-1,4,4-trimethyl-2-tetrazenium cation (TAT+) as its chloride salt 2. Metathesis reactions of salt 2 with energetic anion-transfer reagents lead to the formation of ionic compounds based on the TAT+ cation and the following anions: nitrate 3, perchlorate 4, 5,5′-azobis(tetrazolate) 5·6H2O, picrate 6, and azide 7. The water of crystallization in compound 5·6H2O can be removed to form the anhydrous material 5. All compounds were characterized by analytical and spectroscopic methods, and the solid-state structures of salts 2, 3, 4, 5·6H2O, and 6 were determined by low-temperature X-ray crystallography. We used preliminary energetic testing to gain insight into the sensitivities of the materials towards impact and friction and we assessed their thermal stability by differential scanning calorimetry (DSC) measurements. Additionally, the heats of formation of the energetic compounds were computed by using quantum mechanical methods (CBS-4M) and these values were used to determine some performance parameters of interest for the pure compounds and for their formulations with an oxidizer. Lastly, we calculated the expected decomposition gases of the pure compounds as well as those of the mixtures with an oxidizer.

1,1-Dimethylhydrazine can be readily alkylated with bromoacetonitrile to form 1-cyanomethyl-1,1-dimethylhydrazinium bromide ([(CH(3))(2)N(CH(2)CN)NH(2)]Br, 1). The metathesis reaction of compound 1 led to the formation of a new family of energetic salts based on the [(CH(3))(2)N(CH(2)CN)NH(2)](+) cation and nitrate (2), perchlorate (3), azide (4), 5-aminotetrazolate ([H(2)N-CN(4)](-), 5), 5,5'-azobistetrazolate ([N(4)C-N=N-CN(4)](2-), 7), and picrate (8) anions. The new materials were characterized by elemental analysis, mass spectrometry, and (multinuclear) NMR and vibrational (infrared and Raman) spectroscopies. Additionally, the molecular structure of the [(CH(3))(2)N(CH(2)CN)NH(2)](+) cation in compounds 1, 3, and 8 and that of sodium 5,5'-azobistetrazolate octahydrate (NaZT·8H(2)O) were solved by X-ray diffraction techniques. The hydrogen-bonding networks found in the structure of salts 1, 3, 8, and NaZT·8H(2)O are described using graph-set analysis. The melting and decomposition points of the new compounds were determined by differential scanning calorimetry, and insight into their sensitivity towards impact, friction, and electrostatics was gained by submitting the materials to standard tests. Furthermore, we estimated some performance parameters of interest and predicted the decomposition gases formed upon decomposition of salts 2-8 and of mixtures with an oxidizer. The interesting thermal, sensitivity, and performance properties of some of the compounds described in this work make them attractive towards a prospective energetic application.

The synthesis and characterization of two new binuclear compounds [{Fe(dpia)(NCS)2}2(bpac)]·nCH3OH [n = 0 (1) and 2 (2), dpia = bis(2-picolyl)amine, bpac = 1,2-bis(4-pyridyl)ethyne] are reported. The magnetic susceptibility measurements of the compounds revealed different types of magnetic behavior. Complex 1 displays a two-step spin crossover (SCO) that suggests the occurrence of a mixed [HS–LS] (HS = high spin, LS = low spin) pair at the plateau temperature (145 K), at which about 50 % of the complexes undergo a thermal spin conversion. The high-temperature step is very gradual, whereas the low-temperature step shows a first-order spin transition with a hysteresis width equal to 17 K. Compound 2 manifests a relatively abrupt one-step spin change with a narrow hysteresis of 4 K. The single-crystal X-ray structure of 1 was solved for the [HS–HS] complex at room temperature. Compound 2 was structurally characterized in both [HS–HS] and [LS–LS] spin states at 290 and 110 K. The magnetic and structural characteristics of 1 and 2 were compared with previously reported related binuclear compounds with 4,4′-bipyridine and 1,2-bis(4-pyridyl)ethene spacer ligands. This analysis confirms a recently proposed idea about the key role of the [FeN6] core structural distortions, which are caused by crystal packing and strain effects of terminal and/or bridging ligands, in the spin-crossover behavior of binuclear complexes. This study also revealed the predominant role of inter- vs. intramolecular interactions in the spin transition cooperativity.

Ternary iron silicide aluminide γ-Al3FeSi crystals were grown from two Al—Fe—Si melts quenched in cold water. The crystal structures were determined from single-crystal X-ray data: trigonal symmetry, space group R-3 (n°148), unit cell parameters a = 10.2223(2) Å, c = 19.6791(4) Å (V = 1781 Å3) for the Si-poorer crystal and a = 10.1987(2) Å, c = 19.5320(3) Å (V = 1759 Å3) for the Si-richer one. The structure of γ-Al3FeSi may be described in terms of Al-cubes connected together by Al—Al pairs. The structure contains also Al cuboctaedra with one Fe—Al mixed atom in the center. The average chemical formula obtained from the refinements is Al3FeSi. This phase shows a partial disorder on the aluminium network because of the substitution of aluminum atoms by silicon. This substitution mechanism is at the origin of the large homogeneity range of this phase.

International audience; Three tert-butylsulfanylphthalonitriles have been prepared with optimized synthetic procedures. Their comparative structural analyses have been completed, with a focus on IR and NMR spectroscopy and refined X-ray structural data. Miscellaneous parameters such as UV absorption, melting points, and related polarity of the compounds are summarized.

The syntheses of some novel fluorinated and nonfluorinated hydroxyborate salts, [Q]+[HOB(C6F5)3]− and [Q]+[HOBPh3]− ([Q]+ = aprotic cation), are reported. The reactivities of both salts with group ...

Hydrated alkaline earth metal salts of 5-amino-1H-tetrazole (B) were synthesized by reaction of B with a suitable metal hydroxide in water. All compounds were fully characterized by analytical (elemental analysis and mass spectrometry) and spectroscopic (IR, Raman, 1H and 13C NMR) methods. Additionally, the crystal structures of the magnesium [1·4H2O: triclinic, P, a = 5.940(1) A, b = 7.326(1) A,c = 7.383(1) A, α = 106.10(1)°, β = 106.51(1)°, γ = 111.85(1)°, V = 258.0(1) A3], calcium [2·6H2O: monoclinic, P21/m, a = 6.904(1) A,b = 6.828(1) A, c = 10.952(2) A, β = 94.50(2)°, V = 514.6(1) A3], and strontium [3·6H2O: orthorhombic, Cmcm, a = 6.987(1) A, b = 28.394(2) A, c = 7.007(1) A, V = 1390.3(2) A3] were determined by low temperature X-ray diffraction. Additionally, the (gas phase) structure of the 5-amino-1H-tetrazole anion ([B]–) was also studied by natural bond orbital (NBO) analysis [B3LYP/6-31+G(d,p)]. Lastly, standard tests were used to determine the sensitivity towards impact, friction, and electrostatic discharge of the compounds and the thermal stability was assessed by differential scanning calorimetry (DSC) analysis.

Silica-supported Keggin-type heteropolyacids react with platinum(II) complexes displaying a Pt-CH3 group, leading to the evolution of methane and the formation of an organometallic fragment grafted...

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.

The new complex of Zn(II) with 4-ammino-2,2,6,6-tetramethylpiperidine, [C9H22N2]ZnCl4, has been prepared and characterized by various physicochemical studies. This compound crystallizes in the monoclinic system, with the space group P21/c and the following cell parameters: a = 9.8682(7), b = 7.5164(5), c = 21.019(2) Å, β = 99.003 (7)°, V = 1539.8(2) Å3and Z = 4. The crystal structure was solved and refined to R = 0.024 using 3070 reflections. The atomic arrangement can be described by slightly distorted tetrahedral ZnCl42-anions and 4-ammmonio-2,2,6,6-tetramethylpiperidinium cations holding together by different interactions. The four chlorine atoms of the ZnCl42-tetrahedron are acting as acceptors of hydrogen bonds. The crystal packing is influenced by cation-to-anion N-H…Cl and C-H…Cl hydrogen bonds leading to open framework architecture.

Tetramethyl tin reacts with dodecatungstosilicic acid H 4 SiW 12 O 40 in anhydrous DMSO with evolution of methane to yield the trimethyl tin salt of the heteropolyoxometalate [α-SiW 12 O 40 ][(CH 3 ) 3 Sn(DMSO) 2 ] 4 · 2DMSO. The structure has been determined by X-ray diffraction and shows that there is no direct bond between the polyoxometalate and the tin complex. 119 Sn NMR indicates that tin has quite the same coordination in the solid state and in DMSO solution.

In order to obtain a better anhydrous precursor for various applications in materials science and catalysis, thermal dehydration reactions of Y(TFA)3(H2O)3 (TFA = trifluoroacetate) (A) were investigated. Thermal treatment of A at different temperatures under vacuum (5 × 10−2 mm) for several hours failed to give totally anhydrous yttrium trifluoroacetate (as indicated by IR). Two different complexes, a partially dehydrated [Y(μ,η1:η1-TFA)3(THF)(H2O)]1∞·THF (1) and a partially hydrolyzed [Y4(μ3-OH)4(μ,η1:η1-TFA)6(η1-TFA)(η2-TFA)(THF)3(DMSO)(H2O)] · 6THF (2), were obtained with good and moderate yield, respectively, by crystallization of two different thermally treated batches of A from THF (or THF + DMSO) at room temperature. More efficient dehydration of A could be achieved at 200 °C in a furnace, the obtained anhydrous yttrium tris-trifluoroacetate giving Y(TFA)3(THF)2 (3) on crystallization from THF. All the products were characterized by elemental analyses, FT-IR and 1H NMR spectroscopy as well as thermo-gravimetric analysis. In addition, single crystal X-ray structures are reported for 1 and 2, which show either a terminal (η1 and η2) or bridging (μ,η1:η1) bonding behavior of the TFA ligand.

The atomic arrangement of the title compound, (4-NH2-6-OCH3-C4H3N2)2(H2PO4)2.H2O, can be described by inorganic layers of H2PO4 - anions and water molecules parallel to ab-plane at z = � and z = �, between which organic cations (4-NH2-6-OCH3-C4H3N2) + are located. The crystal packing is influenced by O-H…O, N-H…O, N-H…N and C- H…O hydrogen bonds. All ring atoms of the organic entity are coplanar. The exocyclic N atoms are electron receiving centers, which is consistent with features of imino resonance evidenced by bond lengths.

The crystal structures of chloro-(2-formylpyridinethiosemicarbazono)copper dimethyl sulfoxide solvate (I), bromo-(2-formylpyridinethiosemicarbazono)copper (II), and (2-formylpyridinethiosemicarbazono)copper(II) nitrate dimethyl sulfoxide solvate (III) are determined using X-ray diffraction. In the crystals, complexes I and II form centrosymmetric dimers in which the thiosemicarbazone sulfur atom serves as a bridge and occupies the fifth coordination site of the copper atom of the neighboring complex related to the initial complex through the center of symmetry. In both cases, the coordination polyhedron of the complexing ion is a distorted tetragonal bipyramid. Complex III in the crystal structure forms polymer chains in which the copper atom of one complex forms the coordination bond with the thicarbamide nitrogen atom of the neighboring complex. In this structure, the coordination polyhedron of the central atom is an elongated tetragonal bipyramid. It is established that complexes I–III at a concentration of 10−5 mol/l selectively inhibit the growth of 60 to 90 percent of the cancer tumor cells of the human myeloid leukemia (HL-60).

The synthesis of carbohydrate-based glycogen phosphorylase inhibitors is attractive for potential applications in the treatment of type 2 diabetes. A titanium-mediated synthesis led to a benzoylated C-glucosylated cyclopropylamine intermediate, which underwent a benzoyl migration to afford the corresponding 2-hydroxy-C-glycoside. X-ray crystallographic studies revealed a unit cell composed of four molecules as pairs of dimers connected through two hydrogen bonds. The deprotection of the benzoate esters under Zemplén conditions afforded a glycogen phosphorylase inhibitor candidate displaying weak inhibition toward glycogen phosphorylase (16% at 2.5mM).

A series of layered compounds of the formula { [ Mn 2 II ( NITBzIm ) 3 ] ( X ) } n [X = ClO4 (1) or CnH2n+1SO4 with n = 10 (2), 11 (3), 12 (4), 13 (5), 14 (6), 18 (7)] were obtained by the reaction of the 2-(2-benzimidazolyl)-4,4,5,5-tetramethylimidazolidinyl-1-oxy-3-oxide nitronyl nitroxide radical (NITBzImH) with manganese(II) acetate in methanol and by the successive addition of sodium perchlorate or n-alkylsulfate. The crystal structures of all compounds have been established by Rietveld refinement of their X-ray powder diffraction patterns using the previously reported analogue compound { [ Mn 2 II ( NITIm ) 3 ] ( ClO 4 ) } n obtained with 2-(2-imidazolyl)-4,4,5,5-tetramethylimidazolidinyl-1-oxy-3-oxide (NITImH) as model. Accordingly, all compounds contain the 2D cationic framework of the formula { [ Mn 2 II ( NITBzIm ) 3 ] + } n exhibiting a honeycomb-like structure with alternating manganese(II) ions and radicals and crystallizing in the form of layered compound with perchlorate or n-alkylsulfate anions in between. The series of compounds with n-alkylsulfate anions evidence a linear dependence of the spacing between the layers in respect to the length of the alkyl chain. The variation is small because the chains are almost parallel to the mean plane of the layers. The study of the magnetic behaviors shows that the spacing between the layers deeply influences the magnetic properties. Compounds 1–6 behave as magnets with Curie temperature decreasing when the interlayer spacing increases [52K (1)–30 K (6)]. No 3D ordering was evidenced for compound 7 with larger spacing. A close examination of the magnetization versus magnetic field indicate that compounds 1–6 are a case of weak ferromagnetism due to spin canting within the 2D framework layers. Interestingly, it is found that the canting as well as the interlayers magnetic coupling of dipolar origin increases when the layers come closer. One explanation is that an increase in the dipolar magnetic interaction causes a more accented canting. Alternatively, it may be that when the layers come closer this induces stronger anisotropy through crystal packing effects.

N,N′-Bis[allylamino]glyoxime, N,N′-bis[anilino]glyoxime, and N,N′-bis[1,2,3,4-tetrahydro-5-naphthalenamino]glyoxime have been prepared from corresponding amines and (E,E)-dichloroglyoxime. These ligands gave orange-red compound with NiCl2 in less acidic medium (pH ∼ 5) that are bis(E,E-dioximato)nickel(II) complexes {[(E,E)-Ni(HL)2]} (1a–3a) and green compounds in acidic medium (pH ∼ 2) that are tris(E,E-dioximato)nickel(II) dichloride complexes {[(E,E)-Ni(LH2)3]Cl2} (1b–3b). The crystal structures of all complexes have been determined by X-ray diffraction on a single crystal. The study of absorption spectra of these two types of complexes shows that they may be converted to each other by addition of acids (1a–3a) or bases (1b–3b) and there is no way for the amphi form.

(2S,3R,4S)-4-Hydroxyisoleucine, found in fenugreek, is an insulin secretagogue molecule. Non-natural analogues of (2S,3R,4R)- and (2R,3S,4S)-4-hydroxyisoleucine were efficiently prepared by 1,3-dipolar cycloaddition reactions of chiral nitrones derived from either (−)- or (+)-menthone to alkenes. The cycloadducts, obtained via the exo-approach of the alkenes to the nitrone’s less hindered face, led after a reductive step and cleavage of the chiral auxiliary, to enantiopure non-natural amino acids in good overall yield.

We report here on the synthesis and characterisation of a first iron(II) spin-crossover coordination polymer with the dca spacer ligand, having the formula [Fe(aqin)2(dca)]ClO4.MeOH (aqin=8-aminoquinoline, dca=dicyanamide), which displays a two-step complete spin transition. Variable-temperature magnetic susceptibility measurements and Mössbauer spectroscopy have revealed that the two relatively gradual steps are centred at 215 and 186 K and are separated by an inflection point at about 201 K, at which 50 % of the complex molecules undergo a spin transition. The two steps are related to the existence of two crystallographically inequivalent metal sites, as confirmed by the structural and Mössbauer studies. The crystal structure was resolved at 293 K (HS form) and 130 K (LS form). Both spin-state structures belong to the triclinic P1 space group (Z=2). The complex assumes a linear chain structure, in which the active iron(II) sites are linked to each other by anionic dicyanamide ligands acting as chemical bridges. The Fe-Fe distances through the dca ligand are 8.119(1) and 7.835(1) A in the high-spin and low-spin structures, respectively. The polymeric chains extend along a (1, 0, -1) axis and are packed in sheets, between which the perchlorate anions and methanol molecules are inserted. The complex molecules are linked together by pi-stacking interactions and H-bonding between the H-donor aqin ligands and the perchlorate ions. These structural features provide a basis for cooperative interactions in the crystal lattice. Analysis of the two-step spin-crossover character in this compound suggests that covalent interactions through the spacer ligand do not provide the main mechanism of cooperativity.

1,3-Dipolar cycloaddition reaction of a chiral nitrone derived from (-)-menthone to E/ Z mixtures of crotonaldehyde or ( Z)-but-2-en-1,4-diol opens, by simultaneous creation of three contiguous asymmetric centers, new access to enantiopure (2 S,3 R,4 R)-4-hydroxyisoleucine, respectively in 13% (7 steps) and 34% (6 steps) overall yield.

International audience; A new series of mixed oxalates MM′(C2O4)3(H2O)3·nH2O (M = Cd, Hg, Pb; M′ = Zr, Hf) has been prepared. The crystal structures have been solved from single-crystal and powder diffraction data. The isotypical compounds crystallise with space group P21/c (No. 14). The structures consist of honeycomb layers formed by eight-fold coordinated metals, in a distorted square-based antiprismatic conformation, connected together via oxalates which act as bidentate ligands and also as monodentate in a less-common μ3-bridging mode. Sheets are built from two shifted honeycomb layers and linked to each other through a hydrogen network. The resulting frameworks of the series display a compact two-dimensional arrangement of polyhedra MO8 and M′O8. Weakly-bonded water molecules are located between and within the sheets. Comparisons with the 3D open-framework structures of related metal oxalates are made. The dehydration processes occur in three or four steps. The final products are MO, M′O2 and PbZrO3 resulting from the sublimation of PbO in air. The size of PbZrO3 crystallites, which are on average isotropic, has been evaluated to be 1055 Å from line-broadening analysis.

International audience; Application of known dialkyl ketene di- and trimerization to more complex precursors could readily open the route to highly functionalized symmetrical cyclobuta-1,3-diones and cyclohexa-1,3,5-triones. We report herein the results on three substrates containing either a C=C double bond or a protected glycol moiety as illustrative functionalized groups. The nature of the substituents is found to be crucial: while cyclopentenyl and more constrained dioxolanocyclopentenyl precursors efficiently dimerize, a diallylic derivative fails. At the millimolar scale, methoxide-catalyzed trimerization shows limited reproducibility, even for the reported substrate tetramethylcyclobuta-1,3-dione. However, systematic studies, including the use of microwaves, demonstrate that formation of symmetrical trimers is favored under solvent-free conditions and conventional heating, which allowed us to isolate and characterize trispiro[4.1.4.1.4.1]octadeca-2,9,15-triene-6,12,18-trione.

Chemical preparation, crystal structure, and NMR spectroscopy of a new trans-2,5-dimethylpiperazinium monophosphate are given. This new compound crystallizes in the triclinic system, with the space group P-1 and the following parameters: a = 6.5033(3), b = 7.6942(4), c = 8.1473(5) A, α = 114.997(3), β = 92.341(3), γ = 113.136(3), V = 329.14(3) A3, Z = 1, and Dx = 1.565 g cm−3. The crystal structure has been determined and refined to R = 0.030 and R w(F 2) = 0.032 using 1558 independent reflections. The structure can be described as infinite [H2PO4] − chains with (C6H16N2)2+ organic cations anchored between adjacent polyanions to form columns of anions and cations running along the b axis. This compound has also been investigated by IR, thermal, and solid-state, 13C and 31P MAS NMR spectroscopies and Ab initio calculations.

A new end-to-end azido double-bridged copper(II) complex [Cu(2)L(2)(N(3))2] (1) was synthesized and characterized (L=1,1,1-trifluoro-7-(dimethylamino)-4-methyl-5-aza-3-hepten-2-onato). Despite the rather long Cu-Cu distance (5.105(1) A), the magnetic interaction is ferromagnetic with J= +16 cm(-1) (H=-JS(1)S(2)), a value that has been confirmed by DFT and high-level correlated ab initio calculations. The spin distribution was studied by using the results from polarized neutron diffraction. This is the first such study on an end-to-end system. The experimental spin density was found to be localized mainly on the copper(II) ions, with a small degree of delocalization on the ligand (L) and terminal azido nitrogens. There was zero delocalization on the central nitrogen, in agreement with DFT calculations. Such a picture corresponds to an important contribution of the d(x2-y2) orbital and a small population of the d(z2) orbital, in agreement with our calculations. Based on a correlated wavefunction analysis, the ferromagnetic behavior results from a dominant double spin polarization contribution and vanishingly small ionic forms.

The synthesis, magnetic properties and single crystal study of a new spin crossover compound [Fe(EPPA)(bpym)](ClO4)2 with EPPA = N-(2-aminoethyl)-N-(3-aminopropyl)-2-(aminomethyl)pyridine, bpym = 2,2′-bipyrimidine are reported. Variable-temperature magnetic susceptibility data collected in the temperature range 10–294 K reveal the occurrence of a relatively cooperative spin transition with T1/2 = 108 K. The crystal structure of [Fe(EPPA)(bpym)](ClO4)2 was determined by single-crystal X-ray diffraction method. The structure of the complex consists of mononuclear [Fe(EPPA)(bpym)](ClO4)2 units. The potentially bis-bidentate bpym ligand acting as a bidentate one, is coordinated to iron(II) in cis-position by two nitrogen atoms. The four remaining positions in the pseudooctahedral [FeN6] core are occupied by one pyridinic and three aliphatic nitrogens of the EPPA ligand. The network of cooperative links in the crystal lattice is represented by H-bonding and π stacking interactions.

The reactions between [Y(TFA) 3 (H 2 0) 3 ] and either [Cu(TFA) 2 -(MeOH)] or [Ba(TFA) 2 ]∞ in the presence of excess N-methyldiethanolamine (mdeaH 2 ) have been investigated in relation with their use as precursors for high Tc superconductors. They afford the heterometallic Y 3 Cu complex [CuY 3 (μ 3 -OH]-(μ-η 3 :η 1 -mdeaH) 3 (μ 3 η 3 :η 1 :η 1 -mdeaH) 2 (η 2 -TFA)(μ,η 2 -TEA)2] (TFA) 2 (H 2 0) (1) and the homometallic Ba-TFA ID polymer (TFA)2(H2O) (1) and the homometallic Ba-TFA 1D polymer [Ba 3 (η 3 -mdeaH2)2(μ-η 3 :η 1 -mdeaH2)2(η 1 -TFA)2(η 2 -TFA)2(μ 3 -η 2 :η 2 :η 1 -TFA) 2 ] 1 ∞, (2), respectively, in high yield. These compounds were characterised by X-ray diffraction and FT-IR, ESR (for 1) and NMR (for 2) spectroscopy. Single-crystal X-ray diffraction studies show the versatile bonding modes of the trifluoroacetate and N-methyldiethanolamine ligands, with the former acting not only as a terminal (η 1 and η 2 ) or bridging-chelating (μ,η2 and μ 3 -η 2 :η 2 :η 1 ) ligand but also as a counterion, whereas the latter, either protonated or partially deprotonated, binds the metal centres in a chelating (η 3 ) or bridging-chelating (μ,η3:η1 and μ 3 -η 3 :η 1 :η 1 ) manner. The triangular Y 3 unit [3.480(6)-3.550(6) A] in the cation of 1 consists of one nine-coordinate and two eight-coordinate Y atoms, the former of which are quite scarce in alkoxide chemistry. The unique feature of the 1D polymeric structure of 2 is the secondary F...cation bond, which has not been observed so far for TFA ligands. In addition, it is the only example where the Ba atom is linked to monodentate, bidentate and bridging trifluoroacetate ligands simultaneously.

An ionic heterometallic species [Y(DMF)8][Cu4(µ3-I)2(µ-I)3I2] (1) was isolated from a solution of CuI, NH4I and YI3(PriOH)4 in DMF–isopropoxyethanol, and was converted in a confined environment by progressive substitution of the DMF ligands with water molecules first into a 1D zig-zag structure [Y(DMF)6(H2O)2][Cu7(µ4-I)3(µ3-I)2(µ-I)4(I)]1∞ (2) and finally into a 2D sheet [Y(DMF)6(H2O)3][CuI7CuII2(µ3-I)8(µ-I)6]2∞ (3) by H-bond templating.

The reaction between BaI2 · 2H2O and NaHFIP [HFIP = OCH(CF3)2] in a 1:1 stoichiometry gave the heterometallic compound NaBaI2(HFIP)(H2O)(THF)0.5 (1). Attempts to recrystallize 1 in the presence of N- or O-donor ligands lead to redistribution reactions. Barium iodide adducts such as BaI2(DME)3 (2), trans-BaI2(DME)(triglyme) (3) and cis-BaI2(DME)(tetraglyme) (4) were isolated with DME as solvent. A similar behavior was observed for the reaction between BaI2 · 2H2O and NaTFA (TFA = O2CCF3) in a 1:1 stoichiometry in THF, and [Ba(tetraglyme)2]I2 · C7H8 (6) was isolated in the presence of excess tetraglyme. All compounds have been characterized by elemental analysis, IR and 1H NMR as well as single crystal X-ray studies for 3, 4 and 6. Compounds 3 and 4 are covalent adducts with eight- and nine-coordinate barium, respectively. Compound 6 is an ionic compound where two tetraglyme ligands wrap the 10-coordinate barium cation in a helical fashion. The presence of DME actually allows the coordination number of barium in the mixed-ligand adducts 3 and 4 to be tuned. The average Ba–O bond lengths (2.80 for 3 to 2.87 A for 6) reflect the coordination number of the metal. The same observation is valid for the average Ba–I bond distance, 3.442 for 3 vs. 3.536 A for 4.

A single source precursor, NaGd(tfa)4(diglyme) is prepared from a THF solution of Na(tfa), Gd(tfa)3(H2O), and diglyme (room temperature, 5 h; 83% yield).

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.

SSCI-VIDE+CDFA+SMR:SMA:HCH:SDA; International audience; The strategy of reacting SnCl4 with M(OR)(x) provided a convenient and quantitative approach to new heterobimetallics with a simple addition formula, [SnCl4M(OR)(x)(HOR)(y)] (M = Ti, Nb, Ta; R = Et, Pr-i, x = 4, 5; y = 0-2) or sometimes an oxo complex [SnCl3(O)Ti-2(OPri)(7)(HOPri)(2)]. The alcoholysis reactions of these heterometallics afforded mixed alkoxo complexes [SnCl4(mu-OEt)(2)M((PrO)-O-i)(x)((PrOH)-O-i)(y)] [M = Ti (x = y = 2), Nb, Ta (x = 3, y = 1)] under mild conditions, or a planar rectangular oxo product [SnCl3(mu-OEt)(2)Nb-(OEt)(2)(EtOH)(mu-O)](2) at refluxing/extended stirring time. DFT calculations shed light on the stability and reactivity of these complexes. The use of these thoroughly characterized heterometallics as sol-gel precursors suppresses the formation of the undesired SnO2 grains, which are difficult to be sintered to a high density. The combined approach of using bottom-up synthesis of mixed Ti0.5Sn0.5O2 nanoparticles and Spark Plasma Sintering allowed the successful densification of chloride-free mixed-metal oxide ceramics. The influence of thermal treatment before sintering on the density and spinodal decomposition of the TiO2-SnO2 pellets is reported.

A paramagnetic quality may be established in an aqueous sample if it contains a molecular probe that responds to the addition of a chemical analyte by turning from a diamagnetic state into a paramagnetic one (off–on). We explore here a stable, low-spin, binary iron(II) complex that stores so much potential energy that its transformation by the target analyte leads to its fragmentation into a high-spin complex despite the imposing strength of the chelate effect. The underlying ligand is a mixed aminal, the components of which can be freely varied to optimize response kinetics with the initial probe stability preserved. With decreasing leaving-group character of the azole component, the probe stability improves, and the response kinetics diminish. An optimal arrangement can be found with a pyrazole paired with an electron-deficient aromatic carbaldehyde component (nitro substitution). The drastic electronic reversion associated with the reduction of the nitro group to an amino group is the principal reason for the observation of an initially stable probe that suffers swift fragmentation when reacted with a reductive analyte.

Bottom-up synthesis of a series of GdF3 nanocrystals (NCs) co-doped with 20 mol% Yb3+, 2 mol% Tm3+ and varying amount of Na+ ions is reported using novel molecular precursors [Ln2(TFA)6(diglyme)2] [Ln = Gd (1), Tm (2), Yb (3)] and [Na4(TFA)4(diglyme)]∞ (4) [TFA = CF3COO−; diglyme = MeO(CH2CH2O)2Me]. The single crystal X-ray structures of the new complexes 1–4, which act as excellent precursors because of the absence of water molecules and the ability of the diglyme ligand to behave as a capping reagent during decomposition to render the nanoparticles monodisperse in organic solvents, show a versatile bonding mode of the TFA (dangling η1 or bridging μ,η1,η1; μ4-η1:η1:η1:η1- and μ4-η1:η1:η1:η2 (O, F)) and diglyme (η3 or μ-η3:η1) ligands. The influence of Na+ ion doping on the phase change and upconversion emissions of these GdF3: Yb3+, Tm3+ NCs was studied and compared with the upconversion (UC) intensity of the well-known upconverting NaGdF4: Yb3+, Tm3+ NCs. Among the several UC samples studied, the GdF3: Yb3+, Tm3+ NCs with 30 mol% Na+ seemed to be the most promising as a red emitting UC phosphor, emitting more photons than the NaGdF4: Yb3+, Tm3+ UC NCs in the near IR region.

The non-centrosymmetric materials Zn(IO3)2, Mn(IO3)2, Co(IO3)2, Mg(IO3)2and β-Ni(IO3)2have been synthesised by evaporation of nitric acid solutions of metal salts and lithium iodate. All these compounds are isostructural and their structures were characterised both by X-ray diffraction on powder and single crystals. They crystallise in the monoclinic crystal system, space-group typeP21(no. 4) with a pseudo-hexagonal lattice, as shown by the lattice parameters of Mn(IO3)2for example:a= 11.247(1) Å,b= 5.045(1) Å,c= 11.246(1) Å, β = 120.02(1)°,V= 552.5(1) Å3, Z = 4. This monoclinic symmetry witha∼cand β ∼ 120° leads to a three-individual pseudo-hexagonal twin by pseudo-merohedry. The structure reveals a three-dimensional network in which each octahedrally coordinated cation is linked to ten othersviaiodate bridges. All these metal iodates generate second harmonics.

We report here on the synthesis and characterisation of a new iron(II) spin-crossover coordination polymer of formula [Fe(aqin)2(4,4′-bpy)](ClO4)2·2EtOH (aqin = 8-amino-quinoline, 4,4′-bpy = 4,4′-bipyridyl), with a linear chain structure. Variable temperature magnetic susceptibility measurements revealed a relatively abrupt HS ↔ LS spin transition, with T1/2 = 220 K (temperature for which the HS fraction is equal to 0.5). The crystal structure was resolved at 293 K (HS form) and 80 K (LS form). Both spin state structures belong to the monoclinic space group C2/c (Z = 4). The complex assumes a one-dimensional linear chain structure, in which the active iron(II) sites are linked to each other by rigid rodlike 4,4′-bipyridyl molecules acting as chemical bridges. The Fe–Fe distance through the 4,4′-bpy ligand is 11.485 and 11.147 A in the high-spin and low-spin structures, respectively. The polymeric chains extend in the b direction and form sheets parallel to the bc plane. They are linked together by π-stacking interactions and H-bonding between the H-donor aqin ligands and the perchlorate ions. Those structural features provide a basis for cooperative interactions.