Molecular structures of (tBu)Ga(S2CNnPr2)2 and (iPrO)Ga(S2CNEt2)2: An example of an unusual ligand pseudorotation

The molecular structures of (^tBu)Ga(S₂CNⁿPr₂)₂ (1) and (ⁱPrO)Ga(S₂CNEt₂)₂ (2) have been determined. The variation in the geometries observed for bis-dithiocarbamate compounds of gallium, (X)Ga(S₂CNMe₂)₂ (X=Cl, ⁱPrO, ^tBu) do not lie along the Berry pseudorotation pathway for the square-based pyramid to trigonal bipyramid geometrical transition. Instead, the structures appear to lie on an unusual ligand two-step, Texas, pseudorotation mechanism which results in a highly distorted trigonal bipyramidal geometry. Crystal data: (1) monoclinic, P2₁,/c, a = 9.786(1), b = 29.218(3), c = 9.452(1) Å, = 108.379(9)°, V = 2564.7(5) ų, and Z = 4. (2) Monoclinic, P2₁ /c, a = 10.980(3), b = 15.673(4), c = 12.461(3) Å, = 97.47(2)°, V = 2126.2(9) ų and Z = 4.     

Preparation and crystal structures of the Ce(IV) β-diketonates, [Ce(tmhd)4] and [Ce(pmhd)4] (tmhd =2,2,6,6-tetramethylheptane-3,5-dionate and pmhd = 1-phenyl-5-methylhexane-1,3-dionate)

The cerium(IV) -diketonate compounds [Ce(-diket)₄] [where -diket = tmhd (2,2,6,6-tetramethylheptane-3,5-dionate) 1, pmhd (1-phenyl-5-methylhexane-1,3-dionate) 2] were prepared by reacting cerium(IV) ammonium nitrate [CAN; Ce(NH₄)₂(NO₃)₆] with the respective Na(-diket) compound in ethanol, and structurally characterized by single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic space group with a = 12.472(4), b = 19.972(5), c = 21.436(3) Å, = 97.05(7), = 90.16(2), = 106.55(3)°, V = 5076(2) ų, Z = 4, T = 150(2) K. Compound 2 crystallizes in the monoclinic space group P2₁/n. with a = 14.817(6), b = 17.123(6), c = 19.146(3) Å, = 105.46(4)°, V = 4682(3) ų, Z = 4, T = 150(2) K. Crystals of 1 contain two independent [Ce(tmhd)₄] molecules, with four chelating tmhd ligands bonded to each metal in a distorted dodecahedral arrangement; the cerium atom in 2 is also bonded to four chelating pmhd ligands but in this case the coordination geometry is closer to square antiprism. Both complexes are air and moisture stable. Sublimation studies reveal that 1 sublimes almost quantitatively, while 2 is comparatively involatile.     

Crystal structure of 1,3-di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine

The crystal and molecular structure of 1,3-di-2-[(4-methoxyphenyl)-1-diazenyl]imidazolidine (1) has been determined by single crystal X-ray diffraction analysis. This novel bis-triazene assumes a close-to planar structure with the aryltriazene moieties aligned in diametrically opposed directions, unlike many other previously reported bis-triazenes, which assume a folded structure. The structure of 1 is compared with the closely related, non-cyclic bis-triazene analogue (2), and also compared with the structure of the simple mono-triazene (3). Crystal data: 1 C₁₇H₂₀N₆O₂, monoclinic, space group C2/c, a = 34.948(3), b = 5.925(5), c = 8.1225(6) Å, = 100.8420(10)°, and V = 1652.0(2) ų, for Z = 4.     

A structural study on gallium and indium β-diketonates

In an attempt to prepare pentacoordinate chlorobis(-diketonato) gallium(III) and indium(III) complexes only the corresponding tris-products, Ga(PhCOCHCOPh)₃ (1), Ga(^tBuCOCHCO^tBu)₃ (1a), and In(PhCOCHCOPh)₃ (2), could be isolated. The crystal and molecular structures of 1 and 2 were determined. Both the complexes were found to have triclinc crystal system, with P1 space group. Cell parameters: 1 – a = 9.913(3) Å, b = 10.534(6) Å, c = 18.05(2) Å, = 93.86(5)°, = 94.40(4)°, = 106.58(4)°, V = 1805(2) ų, z = 2; 2 – a = 10.507(3) Å, b = 11.448(3) Å, c = 16.322(4) Å, = 107.38(2)°, = 97.38(2)°, = 102.23(2)°, V = 1792(1) ų, z = 2.     

Synthesis,thermal reactivity and structure of 1,2-bis(4-hydroxy-3-methoxyphenylethynyl)benzene

The crystal structure of the new enediyne 3 was determined by X-ray diffraction. 3 crystallizes in the orthorhombic space group Pbca (No. 61) with a = 12.7148(9) Å, b = 7.4872(8) Å, c = 38.890(4) Å, = = = 90 and Z = 8. The three-dimensional structure is characterized by an 8-membered cyclic array linking four molecules of 3 by hydrogen bonding between phenolic and methoxy groups. Furthermore, stabilization by –-stacking and CH s interactions is present. The important cd distance (between the two terminal acetylene carbons of the enediyne) which is relevant for the Bergman cyclization, was determined to 401 pm, being in good agreement with the high cyclization barrier ( G = 147.9 kJ mol^–1 at 220C) that was determined by differential scanning calorimetry (DSC).     

Six-coordinated zinc complexes: [Zn(H2O)4(phen)] (NO3)2·H2O and [ZnNO3(H2O)(bipy)(Him)]NO3 (phen = 1,10-phenanthroline, bipy = 2,2′-bipyridine, and Him = imidazole)

Two novel six-coordinated zinc complexes, tetra-aqua(1,10-phenanthroline)zinc dinitrate monohydrate, [Zn(H₂O)₄(phen)](NO₃)₂·H₂O (1) and aqua(2,2-bipyridine)(imidazole)-nitratozinc nitrate, [ZnNO₃(H₂O)(bipy)(Him)]NO₃ (2) were prepared. Compound 1 crystallizes in the monoclinic space group P2₁/c with a = 8.780(4), b = 13.609(4), c = 15.368(5) Å, = 93.86(2)°C, V = 1832.1(12) ų. In 1, a phenanthroline molecule chelates the zinc atom and four water molecules complete the octahedral geometry around the metal. Compound 2 crystallizes in the monoclinic space group P2₁/n with a = 7.250(1), b = 24.554(4), c = 10.258(2) Å, = 107.880(10)°, V = 1737.9(5) ų. In 2, a bipyridine molecule and a nitrate anion chelate the zinc atom. An imidazole molecule and a water molecule then complete the six-coordinated geometry around zinc. The intermolecular packing is controlled by hydrogen bonding, especially in 1 and by stacking. The thermal stability of the compounds and the loss of water molecules and ligands was monitored by a thermogravimetric study.     

Molecular structures of M(tfac)3 (M=Al, Co) and Cu(H2O)(fod)2: Examples of unusual supramolecular architecture

The molecular structures of Al(tfac)₃ (1), Co(tfac)₃ (2) (H-tfac = 1,1,1-trifluoroacetylacetone) and Cu(H₂O)(fod)₂ (3) (H-fod = 1,1,1,2,2,3,3-hepta-fluoro-7,7-dimethyloctane-4,6-dione) have been determined. The metal coordination spheres in compounds 1 and 2 are essentially the same as the respective M(acac)₃ derivatives. Despite the isomorphous nature of the structures of compounds 1 and 2, the identity of the nearest intermolecular van der Waals contacts are altered by minor changes in the metal coordination sphere. The geometry about copper in compound 3 is close to that of an ideal square bipyramid with the -diketonate ligands occupying the basal plane. The water ligand in each molecule of compound 3 is hydrogen bonded to an oxygen of a -diketonate ligand on an adjacent molecule resulting in the formation of dimers, which form rods along the y-axis due to weak C–F···Cu interactions. Crystal data: (1) orthorhombic, Pca2₁, a = 14.949(3), b = 19.806(4), c = 13.624(3) Å, V = 4033(1) ų, and Z = 8, and (2) orthorhombic, Pca2₁, a = 14.930(3), b = 19.620(4), c = 13.540(3) Å, V = 3966(1) ų, and Z = 8,; (3) monoclinic, P2₁/c, a = 12.447(3), b = 10.486(2) c = 21.980(4) Å, = 102.65(3)°, V = 2799(1) ų, and Z = 4.     

Crystal structures of a series of 3,8-di[-2-aryl-1-azenyl]-1,3,6,8-tetraazabicyclo[4.4.1]undecanes

The crystal and molecular structure of a series of 3,8-di[-2-aryl-1-azenyl]-1,3,6,8-tetraazabicyclo[4.4.1]undecanes (1–5) have been determined by single crystal X-ray diffraction analysis. In all five compounds, the tetraazabicycloundecane portion of the molecule assumes a cage-like, folded structure with the aryltriazene moieties aligned approximately parallel; the structure is held in the folded configuration by either intramolecular or intermolecular – stacking forces. Crystal data: 1 C₁₉H₂₂N₁₀O₄, monoclinic space group P2₁/c, a = 10.1846(7), b = 9.9556(7), c = 20.819(2) Å, = 98.725(1)°, V = 2086.5 (3) ų, Z = 4; 2 C₂₃H₂₈N₈O₄, triclinic, space group P, a = 6.7064(7), b = 12.9662(14), c = 14.054(2) Å, = 94.796(2), = 91.621(2), = 104.836(2)°, V = 1175.7(2) ų, Z = 2; 3 C₁₉H₂₂N₁₀O₄, monoclinic, space group P2₁/c, a = 14.237(2), b = 13.520(2), c = 11.5805(12) Å, = 113.514(2)°, V = 2044.0(4) ų, Z = 4; 4 C₂₁H₂₂N₁₀, monoclinic, space group C2/c, a = 54.247(3), b = 11.5531(7), c = 12.9670(7) Å, = 95.710(1)°, V = 8086.4(8) ų, Z = 16; 5 C₂₅H₃₂N₈ 0₄, monoclinic, space group P2₁/c, a = 10.2908(7), b = 16.5687(12), c = 15.1662(10) Å, = 94,188(1)°, V = 2579.0(3) ų, Z = 4.     

Crystal structure of Al(tBu)3(NH2CH2CH2Ph): A molecular “slinky”

The molecular structure of Al(^tBu)₃(NH₂CH₂CH₂Ph) is determined by the crystal packing of the phenyl rings and the pseudo spherical Al(^tBu)₃ units, and may be viewed as a layered structure consisting of double sheets of the phenyl rings and the Al(^tBu)₃ units. The Al–N–C–C linkage shows severe disorder as a result of its flexibility. The structure of Al(^tBu)₃ (NH₂CH₂CH₂Ph) can be likened to a molecular slinky, in which the rigid ends are fixed in space by molecular packing forces, leaving the interior link to adopt multiple orientations. Crystal data: orthorhombic, Cmca,a=13.282(9),b=25.01(1),c=13.210(9), Å,V=4388(10) ų,Z=4,R=0.0957,R _w=0.0957.     

Structural characterization of Elisabatin B and Elisabatin C

X-ray structures of Elisabatin B (1) and Elisabatin C (2) have been determined. Crystal data for 1: Triclinic, P (No. 2), a = 7.528(2) Å, b = 9.404(2) Å, c = 11.414(2) Å, = 75.363(3)°, = 86.668(4)°, = 89.683(4)°, and Z = 2. Crystal data for 2: Monoclinic, P2₁/c (No. 14), a = 8.242(2) Å, b = 14.870(2) Å, c = 13.060(2) Å, = 101.458(3)°, and Z = 4. Both compounds are highly unsaturated leading to extended aromatic conjugation. They show different intermolecular O–HO hydrogen bonds, via which 1 forms dimers, and 2 zig-zag polymeric chains.     

Conformations of 2-C:1-N-carbonyl-2-deoxy-d-glycopyranosylamines

Geometry and molecular conformation of theN-toluenesulfonyl1 andN-acetyl-2 derivatives of peracetylated 2-C:1-N-carbonyl-2-deoxy--d-glucopyranosylamine were investigated with the use of X-ray diffraction methods. Compound1 (C₂₀H₂₃NSO₁₀) crystallizes in the monoclinic P2₁ space group, withZ=2 anda=8.238(1),b=7.988(1),c=16.928(2)Å, =99.12(1)°. Compound2 (C₁₅H₁₉NO₉) crystallizes in orthorhombic P2₁2₁2₁ space group withZ=4 anda=8.385(1),b=8.550(1),c=24.000(2) Å. Analysis of differences in bond lengths and angles between compounds1 and2 and other compounds of this class showed that the electronwithdawing effect by the residue located at the nitrogen atom can be manifested by lengthening of the -lactam C-N bonds, with simultaneous shortening of the distance between two carbon atoms at the ring fusion. Semi-empirical calculations suggested that the title compounds displayed two positively charged centers, susceptible for attack of nucleophiles, one at the carbonyl group of -lactam and the second at the anomeric carbon atom. Atomic charges, however, calculated for compounds1 and2 did not explain their different reaction directions during alcoholysis.Part 3. For part 1 and 2, see Refs. 5 and 6.     

Supramolecular structure of tetrakis-μ-(4-chloro-3-nitrobenzoato)-bis(methanol)dicopper(II)

The title compound, [Cu₂(II)(4-Cl-3-NO₂–C₆H₃CO₂)₄(CH₃OH)₂] or [Cu₂(4-chloro-3-nitrobenzoate)₄(MeOH)₂] has been prepared and its structure determined using X-ray crystallography. The complex crystallizes in the triclinic space group P-1 with a = 9.6887(9)Å, b = 10.6448(9)Å, c = 11.4194(10)Å, = 108.094(2), = 110.682(2), = 105.055(2), V = 952.691(15)ų, and Z = 1. The structure consists of centrosymmetric dimers in which the Cu(II) atoms display a square pyramidal CuO₅ coordination, with four carboxylate O atoms in the basal plane [CuO 1.951(2)–1.968(2)Å] and the methanol O atoms in the apical position [CuO 2.170(2)Å]. The Cu atoms are 2.614(1)Å apart and are bridged by four benzoate groups. The discrete dimers are extended into 1D chains that result from hydrogen bonding between the coordinated methanol on one Cu(II) dimer and the nitro substituent on an adjacent Cu(II) dimer. The chains are interdigited and held by – stacking interactions forming 3D supramolecular array.     

Synthesis and crystal structure of 7-ethoxyl-4′-hydroxyisoflavone

7-Ethoxyl-4-hydroxyisoflavone was prepared and its crystal structure was examined by X-ray diffraction. Crystallization of the title compound occurs in the monoclinic, space group P2(1)/c with a = 11.144(2) Å, b = 10.209(1) Å, c = 13.191(2) Å, = 113.43(1) and Z = 4. The molecular structure of title compound consists of a benzopyranone moiety, a phenyl moiety, a hydroxyl and an ethoxyl group. The benzopyranone ring is not coplanar with the phenyl ring, the dihedral angle being 46.75. The ethoxyl group is nearly coplanar with its corresponding ring with the torsion angle 175.23(2). Three kinds of hydrogen bond and two kinds of aromatic stacking interaction link the title compounds into a three-dimensional networking structure.     

Crystal and molecular structure of a nickel(II) complex with a macrocyclic [14]N4 ligand

The crystal and molecular structure of a macrocyclic oxamido Schiff base Ni(II) complex [NiL] has been determined by X-ray crystallography. L is the dianion of diethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]tetraazacyclotetradecine-13,18-dicarboxylate. Ni(II) is located in the coordination cavity formed by the four nitrogen donors of the deprotonated macrocyclic oxamido ligand with a distorted square-planar geometry. C–H O hydrogen bonds have been observed in the crystal. The macrocyclic complex crystallizes in the triclinic space group P – 1, with lattice parameters a = 7.977(3) Å, b = 12.581(4) Å, c = 12.679(4) Å, = 112.669(6)°, = 96.849(7)°, = 106.204(7)°, V = 1089.9(6) ų, Z = 2.     

Chemical preparation and crystal structure of 6′-butoxy-2,6-diamino-3,3′azo-dipyridine monohydrate

Chemical preparation, X-ray single crystal, and calorimetric studies of C₁₄H₁₈N₆O·H₂O are described. The compound crystallizes in the triclinic space group, P with unit cell dimensions: a = 6.2640(3), b = 10.9840(4), c = 12.2220(3) Å, = 105.03(2), = 96.96(2), = 101.6(2)°, V = 712.10(5) ų, and Z = 2. The 6-butoxy-2,6-diamino-3,3-azo-dipyridine monohydrate structure is built up from organic layers parallel to the (120) plane linked via O—H···N bond.     

Crystal structures of 4,7-phenanthrolino-5,6:5′,6′-pyrazine tetrahydrate and 1,4,5,8,9,12-hexaazatriphenylene dihydrate

The crystal structures of 4,7-phenanthrolino-5,6:5,6-pyrazine tetrahydrate (I) and 1,4,5,8,9,12-hexaazatriphenylene dihydrate (II) have been determined from low temperature (173 K) x-ray single crystal diffraction data. I crystallizes in the triclinic system, space group P with a = 11.2687(6), b = 12.4766(6), c = 12.7068(7) Å, = 113.4740(10), = 91.605(2), = 114.587(2)°, V = 1449.33(13) ų, and Z = 4. II crystallizes in the orthorhombic system, space group Pca2₁ with a = 18.187(2), b = 9.2576(11), c = 6.9672(8) Å, V = 1173.0(2) ų, and Z = 4. In both structures the planar heterocyclic molecules stack with interplanar distances down to 3.3 Å, which is consistent with self--complexation. The crystal water molecules provide links between the columns of stacked molecules through hydrogen bonds. In each compound the N-C bond lengths fall into two distinct groups (mean values 1.330(3) vs 1.361(1) Å in I and 1.320(3) vs 1.357(5) Å in II), as do the C-C bonds of the central phenyl rings (1.411(4) vs 1.467(1) Å in I and 1.405(5) vs 1.458(4) Å in II).     

Crystal and molecular structure of a new diterpenyl glycoside from Pteris cretica L.

The crystal and molecular structure of a new diterpenyl glycoside, Ptr-1, is presented. The crystal is triclinic, space group P1, with a = 8.2414(8) Å, b = 13.0826(9) Å, c = 6.1427(8) Å, = 95.345(9)°, = 111.589(8)°, = 96.726(7)°, V = 604.9(1) ų, Z = 1. The structure was solved by direct methods and refined by full-matrix least-squares methods to a final R = 0.049 (Rw = 0.099) for 1872 independent reflections. The molecular structure is based on a glycopyranosyl group and a tetracyclic group. The glycopyranosyl group is -D-allopyranosyl group. The tetracyclic group consists of 1 five-membered and 3 six-membered rings.     

Molecular and crystal structure of two nickel(II) 1,2-dithiooxalato-S,S′ complexes using 1-(Rbenzyl)pyridinium cation (R = 4′-bromo-2′-fluoro or 4′-bromo)

[BrFPy]₂[Ni(dto)₂] (1) and [BrPy]₂[Ni(dto)₂] (2) complexes have been prepared by reaction of Na₂[Ni(S₂C₂O₂)₂] and the corresponding 1-(Rbenzyl)pyridinium bromide salt (R₁ = 4-bromo-2-fluoro, R₂ = 4-bromo). The crystallographic data for 1: monoclinic P2₁/c, a = 14.2192(1) Å, b = 14.2533(4) Å, c = 15.6535(3) Å, = 96.463(1)°, V = 3152.34(11) ų, Z = 4. Two cations, [Br₁F₁Py]⁺ and [Br₂F₂Py]⁺, both adopt a conformation where both the aromatic rings are twisted to the corresponding N(1)–C(10)–C(11) or N(2)–C(22)–C(23) reference plane. Data for 2: triclinic , a = 9.4042(3) Å, b = 9.6814(4) Å, c = 10.3357(4) Å, = 80.155(1)°, = 65.245(1)°, = 64.259(1)°, V = 769.68(5) ų, Z = 1. The [Ni(dto)₂]^2– anion exhibits a quasi-planar structure in both complexes. An extensive hydrogen bond network of C–H O is clearly observed in 1 and 2, and two complexes show similar crystal packing.     

Tricarbonyl (η6 arene) chromium(0) complex derived from 8-phenylmenthol chiral auxiliary

(—)-8-Phenylmenthol was prepared and converted to the corresponding tricarbonyl (⁶-arene) chromium(0) complex. Derivitization as the acrylate ester (1) and subsequent X-ray analysis revealed a 1:1 mix of s-cis and s-trans acrylate in the unit cell, and geometric proximity to support a through-space stacking interaction in the case of the s-trans isomer. The dihedral angle between the best planes through the chromium-bound aryl ring and the acrylate group is 19.9° for the s-trans isomer and 34.4° for the s-cis isomer. Crystal data for (1): C₂₂H₂₆O₅Cr, monoclinic, P2₁ (No. 4), a = 10.269(1), b = 10.482(1), c = 19.787(2), = 95.85(1), Z = 4, and D _calc = 1.32 g cm^–3.     

Bis[aqua(2,5-bis(4-pyridyl)-1,3,4-oxadiazole)thiocyanate] cadmium(II): A three-dimensional framework built from hydrogen bonds and π-π stacking interactions

A three-dimensional (3D) network complex [Cd(L)₂(NCS)₂(H₂O)₂], L being 2,5-bis(4-pyridyl)-1,3,4-oxadiazole, has been synthesized and structurally determined by X-ray diffraction analysis: triclinic, space group P-1 with a = 7.8863(9) Å, b = 8.6287(10) Å, c = 11.4696(12) Å, = 94.346(2)°, = 109.331(2)°, = 94.354(2)°, Mr = 713.04, V = 730.13(14) ų, Z = 1. The crystal structure of the title complex reveals that it is a neutral molecule and the Cd(II) ion is at the center of symmetry. Each Cd(II) is six-coordinated and the CdN₄O₂ coordination sphere can be considered as an octahedron. The most striking feature of this complex resides in the formation of a 3D network through hydrogen bonds and - stacking interactions.