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The reported homonuclear Pd4 cluster is presented in relation to structural analogues. Gradual evaporation of the trapped solvent mol­ecules results in a unilateral contraction of the unit cell, transforming it into the solvent-free structure., Attempts to synthesize Au–Pd heterometallic compounds from homonuclear palladium or gold complexes, [Pd(PtBu2)2] and [Au(PPh3)Cl] in a tetra­hydro­furan (THF) solution under a CO atmosphere resulted in a homonuclear Pd cluster, namely penta­kis­(μ-carbonyl-κ2 C:C)tetra­kis­(tri­phenyl­phosphane-κP)tetrapalladium(5 Pd—Pd) tetra­hydro­furan disolvate, [Pd4(CO)5(C18H15P)4]·2C4H8O. The complex mol­ecule lies on a twofold rotation axis. The crystal structure is described in relation to the CH2Cl2 solvate previously determined by our group [Willocq et al. (2011 ▸). Inorg. Chim. Acta, 373, 233–242], and in particular to the desolvated structure [Feltham et al. (1985 ▸). Inorg. Chem. 24, 1503–1510]. It is assumed that the title compound transforms into the latter structure, upon gradual loss of solvent mol­ecules. In the title compound, the symmetry-unique THF solvent mol­ecule is linked to the complex mol­ecule by a weak C—H⋯O hydrogen bond. Contributions of disordered solvent molecules to the diffraction intensities, most likely associated with methanol, were removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9–18] algorithm.

The crystal structures of two mononuclear Cu(II) NH2trz complexes [Cu(NH2trz)4(H2O)](AsF6)2 (I) and [Cu(NH2trz)4(H2O)](PF6)2 (II) as well as two coordination polymers [Cu(μ2-NH2trz)2Cl]Cl·H2O (III) and [Cu(μ2-NH2trz)2Cl] (SiF6)0.5·1.5H2O (IV) are presented. Cationic 1D chains with bridging bis-monodentate μ2-coordinated NH2trz and bridging μ2-coordinated chloride ligands are present in III and IV. In these coordination polymers, the Cu(II) ions are strongly antiferromagnetically coupled with J = -128.4 cm-1 for III and J = -143 cm-1 for IV (H = -JΣSiSi+1), due to the nature of the bridges between spin centers. Inter-chain interactions present in the crystal structures were taken into consideration, as well as g factors, which were determined experimentally, for the quantitative modeling of their magnetic properties. © 2013 by the authors; licensee MDPI, Basel, Switzerland.

International audience; Experimental approaches to tetraphosphonate cavitands bearing fluorenyl-phosphonate bridges are reported. Different routes are described depending on the substitution on the cavitand structure. Tetra-, tri- and di-bridged phosphonate cavitands have been prepared as precursors of fluorescent hosts, for which the stereochemistry is highly dependent on the substitution at the wide rim of the resorcin[4]arene scaffold. The conformational change in 3io tetraphosphonate cavitands has been characterised by X-ray diffraction. These new molecular receptors have been used for the recognition of acetylcholine.

New gallium(III) and iron(III) endohedral complexes were obtained from a hemicryptophane ligand bearing suitable binding sites for octahedral metal coordination. The solid-state structures of the free host and of the complexes were determined by single-crystal X-ray diffraction analysis. The metal ion is linked to the hydrazone nitrogen and the phenolate oxygen atoms, yielding a distorted octahedral geometry around the encapsulated metal. The two isomorphous structures of the metal complexes reveal the exclusive formation of PΔ/MΛ enantiomeric pairs.

New N-salicylidene meta and para aminobenzenesulfonate anions (1 and 2) presenting both reversible thermochromic properties and high thermal stability have been synthesized. These functional organic components have been successfully inserted into inorganic cationic [Cu II(phen) 3] and [Ni II(phen) 3] frameworks, as a proof of concept, affording [Cu(phen) 3](1) 2 (C 1), [Ni(phen) 3](1) 2 (C 2), [Cu(phen) 3](2)Cl·5H 2O·2CH 3CH 2OH (C 3) and [Ni(phen) 3](2)Cl·7H 2O·CH 3OH (C 4), that have all been structurally characterized by single crystal X-ray diffraction. Temperature dependent fluorimetry demonstrates, for the first time, that keto-enol tautomerization of the anion is effective in the organic-inorganic hybrid materials, even though no thermochromism is observed. This insertion method paves the way towards the synthesis of a panel of hybrid multifunctional materials. © 2011 Elsevier B.V. All rights reserved.

The first crystal structures of a dinuclear iron(II) complex with three N1,N2-1,2,4-triazole bridges in the high-spin and low-spin states are reported. Its sharp spin transition, which was probed using X-ray, calorimetric, magnetic, and (57)Fe Mossbauer analyses, is also delineated in the crystalline state by variable-temperature fluorimetry for the first time.

Two mixed-metal clusters, [Ru5PtC(CO)14(COD)] (1) and [Ru6Au2C(CO)16(PPh3)2] (2), were anchored onto a prefunctionalized active carbon support (C) with chelating phosphane groups on its surface. These clusters were also deposited onto the unmodified support (CSX+) for comparison. The incorporation of 1 and 2 on both supports was studied by a combination of SIMS and XPS. When the clusters were anchored onto the functionalized carbon support, SIMS spectra displayed characteristic patterns that were different from those obtained in the case of their deposition on the unmodified support. In the latter case, spectra corresponded to the results obtained with pure unsupported clusters. XPS analyses of the supported species seemed to indicate that the stoichiometry of the clusters was retained after anchoring and that their dispersion was better on C than on CSX+. This indicates that the phosphanes act as anchors for noble metal compounds through a ligand exchange mechanism. The supported samples were then thermally activated and characterized by SIMS, XPS, TEM/EDXS and XRD. Analyses by SIMS showed that the cluster ligand shell was removed during thermal treatment. XPS measurements indicated that the composition of the supported particles corresponded to that of the starting clusters and that the dispersion remained higher in the case of C. Well-dispersed bimetallic-supported nanoparticles (1–2 nm) were obtained when cluster 1 was used as the precursor, whereas anchoring of cluster 2 resulted in its fragmentation leading to supported nanoparticles of variable stoichiometries. Reactions with soluble model molecules were carried out to prove the chemical bonding of 1. Crystallization of the new cluster [Ru5PtC(CO)14{(PPh2CH2)2NC3H7}] confirmed the chemical bonding of cluster 1 onto the C support through a ligand exchange mechanism involving COD.

N-4H-1,2,4-Triazol-4-yl-guanidine hydrochloride (L1) and a heterocyclized 3,4-diamino-4H-1,2,4-triazole hydrochloride (L2) were synthesized in good yields thanks to a transamination reaction of aminoguanidine and diaminoguanidine hydrochlorides, whose mechanism is presented. L1 and L2 crystallize in monoclinic (P21/a) and triclinic (P1) space groups, respectively. Hydrogen bonding interactions dictated by H-donor, acceptor rich ligand framework together with lattice chloride ions in L1 and L2 organize the crystal packing into a three-dimensional (3D) supramolecular network. The crystal structure of L1 is the first one for a 1,2,4-triazole ligand constructed from aminoguanidine. Both L1 and L2 that exist in monocationic form were introduced as supramolecular synthons to prepare Zn(II) complexes. Scanning electron microscopy (SEM) images on a bulk sample of [Zn(L1)2Cl2]Cl2·H2O (1) reveals a spontaneous aggregation of porous balls of coccolith morphology with surface decorated sickle-shaped particles of 100 nm thickness, whereas a powder sample of [Zn(L2)2Cl2]·H2O (2) shows neat rectangular blocks of 470 nm thickness. Colorless crystals of 2 crystallize in a monoclinic space group (C2/c). Zn(II) ions bound chloride with NH6B···Cl(1) = 2.495(2) A and N···H type bonding (N6···H3C3 = 2.743(2) A; N2···H7N7 = 1.989(2) A) affording a 3D supramolecular network. The degree of pyramidality, ΣN = 38°, observed at one of the terminal amines in L2 is still retained in 2, but “flipping” of orientation of attached protons due to directional H-bonding is observed too. Porosity partitioning by mercury porosimetry measurements on 1 and 2 reveals interparticular porosities between 7 and 15 μm. N2(g) and H2(g) gas adsorption capacities of 1 and 2 were measured by BET which shows no preference for N2(g) but a low irreversible H2(g) uptake of 3 cm3/g.

Heteroleptic triphenylphosphine carbonyl palladium clusters of different nuclearities were prepared under mild conditions by only varying the amount of ligand (PPh(3)) used in the synthesis: three different clusters were successfully isolated after CO bubbling in a solution of [Pd(2)(dba)(3)] (dba = dibenzylideneacetone) with 3, 1 or 0.5 equiv of PPh(3), which led, respectively, to [Pd(4)(CO)(5)(PPh(3))(4)] (1), [Pd(10)(CO)(12)(PPh(3))(6)] (2) and [Pd(n)(CO)(x)(PPh(3))(y)] (3) (n approximate to 24). The molecular structures of compounds 1 and 2 were determined by X-ray crystallography. The metal cores in these compounds were shown to consist in a butterfly for 1 and a bridged octahedron for 2. Compound 3 was shown to be at the boundary between molecular clusters and colloidal particles with tentative formulation arising from characterization data. These three clusters and the known [Pd(10)(CO)(12)(PBu(3))(6)] and [Pd(12)(CO)(15)(PBu(3))(7)] were submitted to NaBH(4) reduction. The Pd(4) cluster 1 did not react. The colloidal Pd(n) species led to no isolable product. By contrast, the two Pd(10) and the Pd(12) clusters led to reduction products, isolated as NEt(4)(+) salts. In the case of the reduced Pd(12) cluster, its structure was resolved by X-ray crystallography: the metal core consists of a face-capped octahedron. The reduced species reacted readily with Au(PPh(3))(+), confirming their anionic nature. (C) 2011 Elsevier B. V. All rights reserved.

Coordinating abilities of 4R-1,2,4-triazole derivatives (R = glycine ethyl ester (L1), glycine (L2), diethylamino malonate (L3), methionine (L4) and diethyl aminomethylphosphonate (L5)) towards Zn-II ions have been studied in solution, in solid state and versus three zinc-beta-lactamases. The crystal structure of [Zn-3(L-4)(6)(H2O)(6)] (6) is described; it is the first crystal structure involving a 1,2,4-triazole functionalized methionine. It forms a trinuclear complex with central zinc octahedrally coordinated by only L4, whereas terminal zinc ions coordination sphere is completed by three water molecules. L4 exhibits a dual functionality of a bridging bidentate ligand as well as an anion. A dense hydrogen bonding network connects these trinuclear entity into a 3D supramolecular network. The Zn-II ions in 6 are held at equidistance (3.848 angstrom) which coincidently matches with the corresponding Zn center dot center dot center dot Zn distance in the binuclear zinc enzyme from Bacillus cereus (3.848 and 4.365 angstrom). Among L1-L5 screened for beta-lactamase assay, L4 shows modest inhibition for BcII enzyme. (C) 2010 Elsevier B.V. All rights reserved.

(Chemical Equation Presented) Asymmetric aldol reaction: A domino silylation-aldol reaction between enoyloxazolidinones and various aldehydes has been developed (see scheme). The process catalysed by a copper complex in the presence of a borosilane led to high diastereoselectivities. Yields between 59 and 90 % and d.r. values between 78:22 to 95:5 were obtained. When methacryloyloxazolidinones were used, a controlled chiral quaternary carbon was generated. BPin=4,4,5,5-tetramethyl-1,3,2dioxaborolan-2-yl.

The crystal structures of the title compounds have been determined using X-Ray diffractometry in order to study the effects of capto-dative substitution on molecular geometry. The carbon-carbon central bond is significantly stretched. 2, 3-Bis (ethylthio) -2, 3-diphenyl-1, 4-butanedinitrile (compound A) is triclinic, P1, with a = 15.703 (9), b = 14. 902(5), c = 8.655(4)A, δ = 97.52(3), β = 89.87(4)°, γ = 75.59(4)°, V = 1943.3 A3, Z = 4 and Dx = 1.20 Mg m−3. 2, 3-Bis (ethylthio)-2, 3-bis (p-tolyl)-1, 4-butanedinitrile (compound B) is monoclinic, P2/n with a = 16-872(8), b = 12, O82(5), c = 10.329(5)A, β = 94.16(4)°, V = 2100.0 A3, Z = 4 and Dx = 1.21 Mg m−3.

The crystal structures of five 1,4-butanedinitrile derivatives have been determined using X-Ray diffractometry in order to study the effects of captodative substitution on molecular geometry. (I) meso 2,3-diacetonyl-2,3-bis (tert-butylthio)-1,4-butanedinitrile, C18H28N2O2S2, is monoclinic, P21/c with a = 9.694(6), b = 10.208(4), c = 10.404(4) A, β = 97.46(4) o, V = 1020.8(8)A3, Z = 2. (II) meso 2,3-bis[(acetylthio)methyl]-2,3-bis(tert-butylthio)-1,4-butanedinitrile, C18H28N2O2S4, is triclinic, PI, with a = 12.867(4), b = 11.175(3), c = 10.430(2)A, α = 90.43(2), β = 54.82(2), γ = 103.61(2) o, V = 1175.8(6)A3, Z = 2. (III) meso 2,3-bis(tert-butylthio)-2,3-bis(butyrylmethyl)-1,4-butanedinitrile, C22H36N2O2S2 is monoclinic, C2/c, with a = 22.562(6), b = 10.932(4), c = 10.157(4)A, β = 90.35(4) o, V = 2505.2(8)A3, Z = 4. (IV) meso 2,3-bis (tert-butylthio)-2,3-diethyl-l,4-butanedinitrile, C16H28N2S2, is monoclinic, P21/n, with a = 10.004(2), b = 13.794(2), c = 6.633(1)A, β = 95.61(2) o, V= 910.9(3)A3Z = 2. (V) dl 2,3-diacetonyl-2,3-bis(methylthio)-1,4-butanedinitrile, C12H16N2O2S2, is triclinic, P1, with a = 9.347(3), b = 9.646(1), c = 8.318(2)A, α = 99.70(2), β = 104.65(2), γ = 99.23(2) o, V = 698.8(3)A3, Z = 2. The central carbon carbon bond lengths are very long in the five molecules. Mean C-C distance is 1.593(2)A. Bond angles around central carbon atom take values between 105 and 115°.

Mr = 210.32, monoclinic, P21/a, a = 41.943(7), b = 6.410(2), c = 10.161 (3) A, β= 114.42 (2)°, V = 2487.4(11) A3, Z = 8, Dx = 1.12 gcm−3, MoKα, λ = 0.71069 A, μ = 0.79 cm−1, F (000) = 928, T = 291K, R = 0.058 for 2248 observed reflections. The trans configuration is observed. The two independent molecules of the asymmetric unit have a similar geometry with perfect chair and envelope conformations for respectively the 6- and 5-membered rings.

The structures of the two title compouds have been established by X-ray diffraction analysis The configurations of the products obtained show that the Diels-Alder reaction of the azadiene I and II with vinylsulfones (scheme) occurs with full exo selectivity.

C23H35N4O4+Cl−.2H2O, Mr = 503.08, orthorhombic, C2221, a = 21.661(4), b = 22.820(4), c = 12.568(2)A, V = 6212(2)A3, Z = 8, Dx = 1.08 g. cm−3, CuKα, λ = 1.5418 A, μ = 14.12 cm−1, F(000) = 2160, T = 291K, R = 0.078 for 3133 observed reflections. The molecule assumes a poly-Gly-II type conformation with (ϕ2,Ψ2) values of (-75°,-135°). The two C atoms of the methyl groups of Leu(2) side chain are disordered with two positions for each (56%,44%). The side chain of Leu(1) and the minor component of Leu(2) have the similar conformation characterized by (X1, X21, X22) angles of (-71°,-56°,-179°) and of (-77°,-33°,174°) respectively, close to one of the most frequently observed ones (-60°,-60°, 180°) (1). The corresponding values of the major conformation of Leu(2) are unusual (-77°,44°,142°). The Trp side chain takes an energically defavorable conformation (X1 = 63°, X21 = -15°, X22 = 164°) with the indole ring almost parallel to the CαCβCγ plane instead of being perpendicular to it(2).

The X-ray structure of N-Piv-D-Phe-L-Pro-NHEt(C21H31N3O3) was solved by direct methods from diffractometer data. Crystallized from diethylether solution, orthorhombic, space group P212121, a = 19.336(24) b = 16.818(18), c = 6.488(7)A, V = 2110(4)A3, Dx = 1.18 g cm−3 for Z = 4. MoKα radiation, λ = 0.71069 A; μ = 0.85 cm−1, F(000) = 808. Final R value = 0.084 for 1307 observed reflections. The peptide backbone is in the all-transoid configuration and takes the type II β bend conformation characterized by ϕ1,Ψ1,ϕ2 and Ψ2 values of 61.8°, -123.2°, -84.8° and 0.8° respectively and by an intramolecular hydrogen bond involving the ethylamide NH and the pivaloyl carboxyl oxygen. The phenyl group stacks over the central amide bond in the “extended-to-oxygen” rotamer, thereby facing the prolyl side chain.

C17H25N3O5 (CH3)2SO2 5H2O, Mr = 474.6, triclinic, P1, a = 11.990(4), b = 12.380(11), c = 9.342(3)A, α = 83.92(5), β = 79.99(3), γ = 84.60(6)A, V = 1241(1)A1, Z = 2, Dx = 1.27 gcm−3, MoKa, λ = 0.71069 A, μ = 1.38 cm-1, F(000) = 1020, T = 291K, R = 0.056 for 2854 observed reflections. The title peptide (GLT) adopts an anti-parallel pleated-sheet conformation, very similar to that found in the copper (II) complex of this peptide(1). This confirms that the conformation of this peptide is affected only very slightly by the solvatation. The Leu side-chain of molecule B takes a conformation characterized by X1 = -178°, X21 = 152° and X22 = -85°, which is only observed in D-Leu residue.

The crystal and molecular structure of the title compounds have been established from X-ray diffractometer data. All possess molecular symmetry: I and III with centrosymmetrical molecules are in the meso configuration; II exhibits non crystallographic twofold axial symmetry. Molecular dimensions and conformations are very similar in the three compounds.

The crystal and molecular structure of the title compound, C32H26N4O2, has been determined by direct methods from diffractometer intensities. The structure is that of a racemic formed by dl dimers. Crystal data are as follow: monoclinic, P21/c, a = 9.991 (2), b = 13.709 (6), c = 18.961 (8) A, β = 96.89° (3), Z = 4, Dx = 1.28 Mg m−3

From X-ray measurements at 155K, the electronic deformation densities for 1,1,2,2-ethanetetracarbonitrile(1) and meso 2,3-dimethyl-2,3-bis(p-cyanophenyl)-1,4-butanedinitrile(2) have been obtained by multipolar refinement. Comparison of the maps does not show any indication of substitution effects. The X-X deformation maps obtained for 2,3-dimethyl-2,3-diphenyl-1,4-butanedinitrile(3) show an orientational disorder with a very weak occupation of the second orientation. This explains the abnormal bond lengths that were observed at room temperature.

C35H49N3O3, orthorhombic, P212121, a = 7.142 (1), b = 11.873 (4), c = 37.852 (9)A; V = 3209.7 (15) A3, Dx = 1.16 Mg m−3 for Z = 4. The structure has been solved by direct methods (MULTAN 80) and refined to a final R value of 0.068 for 1920 observed reflections. The absolute stereochemistry of the title compound is shown in 1; the configuration at the asymmetric carbons is C(20)R, C(17)R, C(13)R, C(14)S, C(9)R, C(6)S and C(3)S. The cyclohexene ring A is in a flattened half-chair conformation. The tetrahydropyridazine ring B adopts a sofa like conformation with N (33) located under the mean plane of the ring. The six-membered ring C is close to a D2 twist (boat) form. The cyclopentane ring D adopts a conformation intermediate between a half-chair (C2 symmetry) and an envelope (Cs symmetry). Finally the urazole ring E is almost flat.

From X-ray diffractometry molecular structure of five 2,3-bis(disubstituted)-butanedinitrile or-dimethylsuccinate have been determined. The aim of this study is to analyse the effects of capto-dative substitution on molecular deformation in compounds with tertiary central carbon atoms. (I) meso 2,3-bis (dimethylamino) butanedinitrile, C8H14N4 is monoclinic, P21/α with α=10.545(5), b=6.314(2), c=7.943(3)A, B=109.25(3)°, V=499.3(3)A3, Z=2. (II) meso 2,3-bis(methylthio) dimethylsuccinate, C8H14S2O4, is triclinic, P1 with α=8.349(2), b=5.761(1), c=7.928(2)A, α=71.85(2), β=113.12(2), γ=74.41 (2)°, V=298.0(1)A3, Z=1. (III) dl 2,3-bis(phenylthio)dimethylsuccinate, C18H18S2O4, is orthorhombic, Pbnb with α=15.265(3), b=16.618(4), c=7.063(2)A, V=1791.7(6)A3, Z1 (III) dl 2,3-diphenoxy dimethylsuccinate, C18H18O6 is orthorhombic, Pcab with α=21.612(6), b=17.662(4), c=9.029(2)A, V=3446.5(6)A3, Z=8. (V) dl 2,3-diacetoxy dimethylsuccinate, C18H14O8, is orthorhombic, Pca21, with α=10.879(2), b=13.558(2), α=9.133(2)A, V=1347.1(5)A3, Z=4. The geometry of the five molecules is quite normal. These results are compared with those concerning dimers with quaternary central carbon atoms (R1R2R3C)2 in which a long central C-C bond was found.

X-Ray analysis of the steroidal isoxazolidine derivatives 2 and 3b, which are formed (the latter as the corresponding diacetate 3a) in the reaction of (Z)-3beta, 17beta-diacetoxy-19-nor-5,10-secoandrost-l(lo)-en-5-one (1) with N-methylhydroxylamine, has revealed that both compounds (and therefore also 3a) have the same cis-1beta,5beta-epoxyimino bridge structure. The conformations of the two molecular skeletons are compared.

The structure of the title compound (D:C-Friedours-7-en-3-ol acetate 3β) has been determined by single crystal X-ray diffractometry. Crystal data are as follow: orthorhombic, P212121, a = 8.291(1), b = 11.084(3), c = 30.041 (8) A, V =2761(1) A3, Dx = 1.13 Mg m−3 for Z = 4.

The title reactions lead to unique diastereoisomers of pyrrolizidines 1a [dimethyl 2,3-dehydro-1-methyl-3-cyanopyrrolizidine-1,2-dicarboxylate] or 1b [dimethyl 2,3-dehydro-1-(ethoxycarbonylmethyl)1-3-phenyl-pyrrolizidine-1,2-dicarboxylate] with relative stereochemistry (1a: trans; 1b: cis) established by X-ray diffraction analysis. The heterocycle adopts a different conformation in 1a and 1b.

C15H1N4O4, 2H2O, Mr = 354.41, orthorhombic, P21 21 21, a = 9.019(8), b = 7.909 (3) c = 24.336(23) A, Z = 4, Dx = 1.36 gcm−3, MoKα, λ = 0.71069 A, μ = 1.14 cm−1, F(000) = 752, T = 291K, R = 0.061 for 1014 observed reflections. The molecule adopts a conformation somewhat similar to a segment of a lefthanded α-helix. The side chain of the Trp residue takes an usual conformation described by χ1 = -172° and χ21 = -79°.

(1): C-17H14O4, Mr = 282.30, triclinic, P-1, a = 10.509(2), b = 13.448(1), c = 17.061(2)angstrom, alpha = 67.24(1), beta = 107.72(2), gamma = 103.59(1)-degrees, V = 2099.0(5)angstrom(3), Z = 6, (3 independent molecules), Dx = 1.34 g.cm-3, CuK-alpha, lambda = 1.54178 angstrom, mu = 7.98 cm-1, F(000) = 888, T = 291K, R = 0.052 for 5178 observed reflections. (2): C-17H14O.CH2O2, Mr = 328.32, orthorhombic, P2(1)2(1)2(1), a = 23.614(8), b = 4.691(1), c = 14.327(4) angstrom, V = 1587.1(8) angstrom-3, Z = 4, Dx = 1.37 g.cm-3, CuK-alpha, lambda = 1.54178 angstrom, mu = 8.79cm-1, F(000) = 688, T = 291K, R = 0.074 for 2038 observed reflections. (3): C-17H14O4.C3H6O, Mr = 356.37, triclinic, P-1, a = 7.596(3), b = 9.624(5), c = 13.122(2) angstrom, alpha = 91.54(3), beta = 100.26(3), gamma = 76.30(4)-degrees, V = 916.9(6) angstrom-3, Z = 2, Dx = 1.29 g.cm-3, MoK-alpha, lambda = 0.71069 angstrom, mu = 1.03cm-1, F(000) = 376, T = 291K, R = 0.053 for 1959 observed reflections. In the non-solvated molecule (1), the three independent molecules in the unit cell differ only by the dihedral angle between the benzopyrone and the phenyl ring, 68(1), 86(1) and 84(1)-degrees respectively. For the formic (2) and propionic acid (3) solvates, the dihedral angle between the heterocycle and the phenyl ring are 80(1) and 64(1)-degrees respectively. In the two solvates the hydrogen bonding involving the carbonyl oxygen is alike. It may be thus concluded that this hydrogen bond has no effect on the conformation of 2',6'-dimethoxyflavone.

The configuration of the two isomers obtained by the Diels-Alder reaction of the 2-azadiene 1 with N-phenylmaleimide II (scheme) is established by X-ray diffraction: The cycloaddition takes place with a high endo selectivity. The geometry of the two isomers is similar and the piperidone ring has a twist conformation in both molecules

Heterocyclisations of 1,4-bis-nucleophiles with the tetrahydroazepin-2-one 1 and gamma-butyrolactone 2 gave imidazolidine 9, 12, oxazolidines 3, 10, 13, 15 and thiazolidine 4 as a mixture of two diastereoisomers in various proportions. The structure and the relative configurations of these heterocycles were established by X-ray diffraction analysis and by comparison of F-19- and C-13-NMR data.

The Schmidt reaction of diamantanone has been studied in details. The main products of the reaction were separated by means of the elution chromatography on silica gel. Obtained compounds 10-aza-11-oxohomodiamantane (VI) and 11-aza-10-oxohomodiamantane (IX) were analysed by X-ray diffraction. These compounds as well as 5ax-hydroxy-and 5eq-hydroxy-3-diamantanones were also analysed by using 13C NMR additive rules.

Heterocyclizations of 1,4-bis-nucleophiles with the new 3-trifluoroacetyl-lactams 1a-c differ from 1,2- or 1,3-bisnucleophiles since they proceed without opening of the lactam structure to give benzoxazolidines 4-6, benzothiazolidines 7-9 and benzimidazolidines 13 as mixtures of two disastereoisomers in various proportions. The structure and the absolute configuration of these heterocycles were established by X-Ray diffraction analysis and by comparison of F-19- and C-13-NMR data.

The stereochemistry of the title compound, an azadiene (2), is established by X-ray diffraction analysis. The molecular conformation is discussed.

C13H17N3O4, Mr = 279.30, orthorhombic, P212121, a = 5.743(2), b = 16.072(10), c = 15.317(10)A, V = 1347(1)A3, Z = 4, Dx = 1.38 g. cm−3, MoKα, λ = 0.71069 A, μ = 1.12 cm−1, F(000) = 592, T = 291K, R = 0.036 for 1372 observed reflections. The molecule partly assumes a 310-helical conformation. The side chain of the Phe residue has an unusual conformation characterized by angles X1 = 176° and X21 = 53°.

The structure of L-hydantoino [c]-1, 4-perhydrothiazine (I) and L-N-methyl-hydantoino [c]-1, 4-perhydrothiazine (II) have been investigated using X-ray diffractometer intensities. Crystal data are as follow (I) orthorhombic, P212121, a = 6.106 (6), b = 5.217 (4), c = 22.725 (19) A, V = 723.9 A3, Z = 4. (II) orthorhombic, P212121, a = 5.616 (2), b = 9.414 (2), c = 16.444 (6) A, V = 869.4 A3, Z = 4.

The Grignard reaction of 11 beta-hydroxy-3,3-(ethylenedioxy)-pregn-5-en-20-one (1) affords both epimers (20R) (2) and (20S) (3) of the hydroxy derivative. The configuration R at C20 is established for the predominant epimer by the determination of the X-ray structure of the deketalized analog 4. C27H36O3, M(r)=408.58, orthorhombic, P2(1)2(1)2(1), a = 30.009(11), b = 6.323(1), c = 12.182(9)Angstrom, V = 2312(2)Angstrom(3), Z=4,D-x=1.17 g.cm(-3), CuK alpha radiation (lambda = 1.5418 Angstrom). The final R indice is 0.079 for 2058 observed reflections.

The X-Ray structures of four methyl α, β-diphenylacrylate derivatives were solved by direct methods from diffractometer data. (I) (Z)-methyl β-p-nitrophenyl-α-phenylacrylate, C16H13NO4, is monoclinic, P21/n, with α=8.296 (1), b=6.703(2), c=24.863(5)A, β=96.25(1)°, V=1374.4(5)A3, Z=4, (II) (Z)-methyl α-p-nitrophenyl-β-phenylacrylate, C16H13NO4, is triclinic, P1, with α=14.233(3), b=10.048(2), c=9.907(2)A, α=80.75(1), β=92.98(1), γ=92.48(2)°, V=1395.6(5)A3, Z=4. (III) (E)-methyl β-p-nitrophenyl-α-phenylacrylate, C16H13NO4, is monoclinic, Cc, with α=5.819(2), b=16.610(5), c=14.843(4)A, β=96.14(2)°, V=1426.4(7)A3, Z=4. (IV) (E)-methyl β-methyl-β-p-nitrophenyl-α-phenylacrylate, C17H15NO4, is monoclinic, P21/α, with α=13.751 (4), b=11.145(3), c=10.956(4)A, β=116.42(2)°, V=1503.7(8)A3, Z=4. Molecular conformations are discussed and compared. The aromatic and ester substituents are generally twisted out of the ethylenic bond mean plane to avoid steric hindrance; only phenyl α in molecule II and ester group in III are coplanar with the CC bond. The C (arom.)-CC bond angles are significantly greater than 120°.

Mr = 223.18, monoclinic, P21/c, a = 9.004 (2), b = 12.552 (2), c = 9.416 (3) A, β = 102.18 (2)°, V = 1040.1 (3) A3, Z = 4, Dx = 1.43 g. cm−3, CuKα, λ = 1.5418 A, μ = 10.13 cm−1, F(000) = 464, T = 291K, R = 0.044 for 1200 observed reflections. The two moieties of the molecule are planar and the dihedral angle between them is 79°.

The structure of L-thiazolidine-4-carboxylic acid hydantoin has been investigated using X-ray diffractometer intensities. The conformation of the thiazolidine ring is that of an envelope β+ while the hydantoin is not exactly planar. Crystal data are as follow: monoclinic, P21; a = 10.898(3), b = 5.879(2), c = 5.064(2)A, β = 100.5(2)°; V= 319.0 A3; Z = 2; Dx = 1.65 Mg m−3.

The molecular structures of the acetals 3b and 5a, obtained from (Z) - 38- acetoxy-5, 10-seco-cholest-1 (10)-en-5-one (1) via the cis-(1S, 10R)-epoxide 2, and from (E)-3β-acetoxy-5, 10-seco-cholest-1 (10)-en-5-One (4) via the corresponding (1S, 10S)- and (1R, 10R)-osmate esters, have been determined by X-ray analysis.

Three new γ-lactone norditerpenes with an isopimarane skeleton were isolated from roots, stem and leaf sheaths of Vellozia variabilis. X-ray diffraction analysis established the structure of one of these norditerpenes. The other two were elucidated through spectroscopic data and chemical correlation.

the molecular structure of the title compound, a 15-membered 9,10-epoxy-3-en-4-ol lactone, which is an important intermediate in the reaction sequence correlating steroid compounds with prostaglandin-like derivatives, was determined by X-ray analysis. The (E) stereochemistry around the double bond and the trans-(9R,10R)-configuration at the oxirane ring are established.

Self assembly of N-salicylidene 2-aminopyridine (L1H) with Cu(NO3)(2)center dot 3H(2)O affords [Cu-4(L1)(4)(NO3)(3)(CH3OH)][Cu(L1)(NO3)(2)[(2-aminopyridinium)(NO3)center dot 5CH(3)OH (1) which is composed of an asymmetric [2 x 2] grid-like cationic complex that co-crystallizes with a Cu(II) mononuclear anion. This remarkable tetranuclear unit presents three penta-coordinated and one hexa-coordinated Cu(II) sites. This quadruple helicate structure reveals strong anti-ferromagnetic coupling (J = -340(2) cm(-1)) between Cu(II) ions through a double alkoxo bridge. Reacting L1H with Cu(NO3)(2)center dot 3H(2)O in slightly different conditions affords however a more symmetric tetranuclear grid-like complex: [Cu-4(L1)(4)(NO3)(2)(OH)(2)](2-aminopyridinium)(OH)center dot CH3OH) (2). A dinuclear Ni(II) complex. [Ni-2(L2)(2)(L2H)(2)(NCS)(2)(CH3OH)(2)]center dot 2CH(3)OH (3), obtained with another related donor Iigand (L2H = N-salicylidene 3-aminomethylpyridine) was also prepared. (C) 2010 Elsevier Ltd. All rights reserved.

New trifluoromethylated pyrazoles 5b,c,f have been prepared by condensation of 3-trifluoroacetyl benzolactams 1a,b,c and 2 with hydrazines by opening of the lactam moiety. The structure of pyrazoles was established by X-ray diffraction analysis and by comparison of C-13-NMR data. The geometry of intermediate hydrazones 3c-e and their cyclisations were also investigated.

C27H29N3O7.l/2HCl.3H2O, Mr = 579.84, orthorhombic, P22121, a = 9.816(3), b = 12.365(14), c = 23.394(25)A, V = 2839(4)A3, Z = 4, Dx = 1.36gcm−3, Dm = 1.35gcm−3 (by flotation in dichloromethane/chloroform), CuKα, λ = 1.5418 A, μ = 13.01 cm−1, F(000) = 1228, T = 291K, R = 0.084 for 1788 observed reflections. The conformational angles of the middle residue are somewhat similar to those corresponding to the parallel β-sheet structure with ϕ2 =−107°, ϕ2 = 123°, but no β-type interchain H-bond is formed. The(X1, X21) values for three Tyr residues are respectively, (−65°, −56°), (−166°, 89°) and (−58°, 76°). The X21 value of −56° is the smallest one reported so far for Tyr residues in peptides.

C21H33N3O5H2O, Mr = 425.52, monoclinic, P2, a = 13.387(5), b = 15.452 (7), c = 13.198(5) A, β = 115.74(3)°, V = 2459(2)A3, Z = 4, Dx = 1.15 g. cm−3, MoKα, λ = 0.71069 A, μ = 0.91 cm−1, F (000) = 920, T = 291K, R = 0.071 for 2348 observed reflections. The two independent molecules have quite different conformations. An antiparallel-chain pleated sheet structure is observed at Tyr residue of molecule A and at Leu(2) residue of molecule B, characterized by (ϕ, Ψ) angles of (-130°, 121°) and of (-134°, 140°) respectively. A poly-Gly-II conformation is observed at Leu(2) level of molecule A and at Tyr level of molecule B with (ϕ, Ψ) values of (-114°, 159°) and of (-83°, 137°) respectively. The Leu(2) side chain of molecule A takes an unusual conformation with (X1, X21, X22) angles of (-74°, 48°, -172°). The other side chains have normal conformations.

C10K17N3O4, H2O, Mr = 261.28, orthorhombic, P212121, a = 6.716(1), b = 11.780(1), c = 16.248(1)A, V = 1285.6(2)A3, Z = 4, Dx = 1.35 g. cm−3, CuKα, λ = 1.5418 A, μ = 9.28 cm−1, F(000) = 560, T = 291K, R = 0.063 for 2447 observed reflections. The molecule (hereafter APG) adopts a collagen-like conformation at Pro residue with (φ2, Ψ2) values of (-66.6°, 156.9°) and an extended form at the two terminal residues. The pyrrolidine ring is disordered with two positions for C(6) its conformation is C2-Cγ-endo for the major component (75%) end C2-Cγ-exo for the minor one (25%). The geometry and the main-chain conformation are both in excellent agreement with those found in the tripeptide L-Leu-L-Pro-Gly monohydrate (hereafter LPG)(1,2) It seems that the atoms further than Cγ of the Leu side chain do not affect significantly the conformation of peptide backbone in this case. The twofold screw axis in the LPG crystal structure corresponds to that of the APG in the a direction.