Crystal and Molecular Structures of (Dibenzo-18-Crown-6)(Nitrato-O,O")-Tetrahydrofuranpotassium, [K(DB18C6)(THF)(NO3)]

The (dibenzo-18-crown-6)(nitrato-O,O")tetrahydrofuranpotassium complex [K(DB18C6)(THF)(NO₃)] (I) was synthesized and studied using X-ray diffraction analysis. The crystals are orthorhombic: a= 9.608 Å, b= 9.926 Å, c= 27.234 Å, Z= 4, space group P2₁2₁2₁. The structure was solved by the direct method and refined by the least-squares method in the anisotropic approximation to R= 0.099 over all 2620 measured independent reflections (CAD4 automated diffractometer, MoK radiation). Complex Iin the crystal exists as individual host–guest molecules, the K⁺cation (CN 9) being located in the DB18C6 macrocycle cavity and being coordinated to its six oxygen atoms and to two oxygen atoms of the nitrato ligand on one side of the macrocycle and to the THF oxygen atoms on the other side. The DB18C6 molecule in Ihas a butterfly conformation with approximate C _2V symmetry.     

A doubly deprotonated form of calix[6]arene: Crystal and molecular structure of (calix[6]arene-2H)2−·(HNEt 3 + )2

The doubly deprotonated form of calix[6]arene, with two protonated triethylamines as counter-ions, crystallizes in the monoclinic system: space groupP2₁/n,a=8.465(4),b=17.822(8),c=15.182(6) Å,=90.18(4)°,V=2291(2) ų,Z=2. Refinement led to a final conventionalR value of 0.063 for 1046 reflections. The macrocycle conformation is not apinched cone, usual for freeR-calix[6]arene, but a distorted 1,2,3-alternate cone, since the molecule lies on a symmetry center. Furthermore, one of the torsion angles defined by the methylene bridges is near to zero, which is unusual in calixarene structures. Supplementary Data relating to this article (atomic coordinates for hydrogen atoms, anisotropic displacement parameters for oxygen and nitrogen atoms, and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82182 (7 pages).     

Preparation and structure of (calix[8]arene methyl ether) · 2CDCl3

The methyl ether of calix[8]arene crystallizes from CDCl₃ with two molecules of the solvent per molecule of host. An X-ray structural investigation has shown that the CDCl₃ guests exist within the calixarene framework. The complex resides on a crystallographic center of inversion, and the cavity is roughly circular in projection as measured by the distance between centroids of aromatic rings related by the center: 14.5, 13.9, 10.1, and 11.2 Å. Six of the oxygen atoms are found on the inside and two on the outside. Crystals belong to the triclinic space group witha=11.741(9),b=11.810(9),c=12.484(8) Å, =94.74(8), =104.41(8), =111.30(9)°, andD _c =1.31 g cm^–3 forZ=1. Refinement led to a finalR value of 0.086 for 949 observed reflections. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82038 (10 pages).     

Crystal structure of the 2:1 acetonitrile complex of 18-crown-6

Single crystal X-ray analysis of the 2:1 acetonitrile complex of 18-crown-6 is reported. Crystals of the complex are monoclinic,P2₁/n, witha=9.123(3),b=8.524(3),c=13.676(4) Å, =104.68(3)°, andD _c =1.118 g cm^–3 forZ=2. The complex lies on a center of symmetry, with the crown in theD _3d conformation. Methyl groups of the acetonitrile molecules have weak interactions with the crown oxygen atoms, and are tilted 31.7° from the host's threefold axis. Methyl hydrogen atoms are rotationally disordered about the acetonitrile axis. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82057 (12 pages).     

A reinvestigation of the crystal and molecular structure of (18-crown-6) · 2 CH3NO2:D 3d stabilization via methyl hydrogen-crown oxygen ‘hydrogen bonds’

The title compound was crystallized from hot nitromethane. (18-crown-6) · 2CH₃NO₂ crystallizes in the monoclinic space groupP2₁/n witha=9.066(3),b=8.284(3),c=14.015(7) Å, =101.83(5)^o andD _calc=1.25 g cm^–3 forZ=2. Least-squares refinement using 890 independent observed reflections led to a final conventionalR value of 0.084. The hydrogen atoms were located but not refined. The crown ether resides about a crystallographic center of invertion. There are two nitromethane molecules (one centered above and one below the crown ether) weakly interacting with the crown oxygen atoms via the methyl hydrogens stabilizing aD _3d crown conformation. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82029 (5 pages).     

Reaction of early transition metal complexes with macrocycles. II. Synthesis and structure of TiCl3(H2O) · 18-crown-6, a compound with a unique bidentate bonding mode for the 18-crown-6 molecule

18-crown-6 reacts with TiCl₃ in CH₂Cl₂ to form a complex in which the crown ether functions as a tridentate ligand. Addition of moist hexane affords a molecular complex in which the crown ether functions as a bidentate ligand. A water molecule is bonded directly to the titanium atom and is further hydrogen bonded to three of the oxygen atoms of the crown. The deep blue crystals of the CH₂Cl₂ adduct belong to the monoclinic space groupP2₁/n witha=13.481(8),b=8.021(5),c=21.425(9) Å, =97.32(5)°, and _calc = 1.51 g cm^–3 forZ=4. Refinement led to a conventionalR value of 0.040 based on 873 observed reflections. The Ti–O bond distances for the crown oxygen atoms are 2.123(8) and 2.154(9) Å, while the oxygen atom of the water molecule is bonded at 2.072(8) Å. The octahedral coordination sphere of the titanium atom is completed by the three chlorine atoms at distances of 2.340(5), 2.352(4), and 2.373(4) Å. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82034 (10 pages).     

Reaction of trimethylaluminum with crown ethers. III. The synthesis and crystal structure of (12-crown-4)bis(trimethylaluminum)

The crown ether 12-crown-4 reacts with trimethylaluminum in toluene to form the complex [AlMe₃]₂[12-crown-4]. Attempts to utilize the remaining two oxygen atoms for coordination to AlMe₃ molecules were unsuccessful. The 21 complex crystallizes in the monoclinic space groupP2₁/n witha=11.342(7),b=12.941(4),c=6.973(6) Å, and =95.48(4)°. Refinement led to a finalR value of 0.047 for 925 observed reflections. The molecule resides on a crystallographic center of inversion, and as required by symmetry, the four oxygen atoms are planar. The Al–O bond is strong as revealed by the bond length of 1.977(3) Å. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82013 (9 pages).     

Inclusion of (aminostyryl)-1-methylpyridinium dyes byβ-cyclodextrin and its use for fluorescent-probe studies on association of cationic and neutral molecules withβ-cyclodextrin

An inclusion complex between TRIMEB and (S)-naproxen has been crystallised and characterised by physicochemical methods including X-ray analysis. The complex crystallises in the orthorhombic crystal system, space groupP2₁2₁2₁, witha=15.179(4),b=21.407(5),c=27.67(1) Å andZ=4. The structure was solved using published coordinates for the skeleton atoms of TRIMEB in an isomorphous complex. Refinement by full-matrix least-squares analysis yieldedR=0.0571 for 6573 unique observed reflections. Hydrophobic forces are responsible for the inclusion of the drug, which has its methoxy group buried in the cavity of the host and its propionic acid moiety protruding from the O(2), O(3) side of the TRIMEB molecule. Both host and guest undergo conformational changes on complexation relative to their conformations observed in the TRIMEB monohydrate and naproxen crystal structures respectively. Complex units pack in a screw-channel mode in a head-to-tail fashion with their axes almost parallel to theb-axis.     

An inclusion complex between acetonitrile andp-tert-butylcalix[6]arene

p-tert-Butylcalix[6]arene forms a complex with 1.5 acetonitrile molecules, that are included in the macrocycle cavity. This complex crystallizes in the monoclinic system: space groupP2₁/m,a=14.043(4),b=16.916(11),c=14.199(11) Å,=98.27(6)°,V=3338(4) ų,Z=2 (formula units). Refinement led to a final conventionalR value of 0.113 for 1654 reflections. Thepinched cone conformation of the calixarene is the same as that of the neutral and freeR-calix[6]arene already described. The two acetonitrile molecules interact with some phenyl ring -clouds, a methylene bridge and sometert-butyl groups of the calixarene. Supplementary Data relating to this article (atomic coordinates for hydrogen atoms, anisotropic displacement parameters, selected geometrical parameters and observed and calculated structure factors) are deposited with the British Library as Supplementary Publication No. SUP 82188 (16 pages).     

Synthesis and X-ray crystal structure of tetraethylammonium bis[1,2-di(carbomethoxy)ethane-1,2-dithiolato]oxotechnetate(V)

Summary The (NEt₄)⁺[TcO{SCH(CO₂Me)CH(CO₂Me)}₂]^– compound has been prepared from technetium(V) gluconate and characterized by single crystal x-ray structural analysis (R factor=0.065).The compound crystallizes in the monoclinic space groupP2₁/c witha=12.722(3),b=13.820(4) andc=18.213(5) Å, =107.13(4)° andZ=4. In the complex the technetium atom is close to the center of the base of a square pyramid in which the oxo oxygen is at the apex and the four sulfur atoms form the basal plane. The Tc-S distances average 2.316 Å. The Tc=O distance is 1.672(6) Å. Considerations about the osteotropic behaviour of DMSA labelled with⁹⁹Tc are deduced from the reported results.     

Synthesis and crystal structure of ammonium (picrate) (dibenzo-18-crown-6)

NH₄(Pic)(DB18C6) (Pic=picrate and DB18C6=dibenzo-18-crown-6), (C₂₆H₃₀N₄O₁₃) FW 606.56, arthorhombic,Pmn2₁,a=26.045(5),b=12.055(3),c=8.982(3) Å,V=2820(1) ų,Z=4,D _c =1.429 g/cm³, CuK, =1.54184 Å, (CuK)=9.5 cm^–1,F(000)=1272,T=298 K. The structure has been refined toR=0.0475 for 2617 unique observed reflections. In the lattice the 1:1 complex exists as a 2:2 dimer in which the crown are coupled through the Pic anions and NH₄ ⁺ cations. The asymmetric unit consists of two independent half crown ethers of which two opposite O atoms are on the mirror plane, two half ammonium cations of which the N and two H atoms are also on the mirror plane while the Pic anion is in a general position. Relative to each other, the corwn ethers are shifted by about 7.3 Å alongb and 1 Å alongc. The 1:1 sandwich of NH₄ with DB18C6 and Pic on dimerisation becomes a club pseudo-sandwich with three phenyl rings on either side of the mirror plane, thus forming a nearly parallel stack with a 3.6 Å inter-ring distance. The NH₄ ions hold the structure; two H atoms on the mirror plane are hydrogen-bonded to the opposite oxygens of the crown located on the purely aliphatic part of the ring (2.10(1), 2.06(3) and 2.26(3), 2.05(1) Å) for the two independent crowns, respectively, while the other two H atoms form mirror-related bifurcated hydrogen bonds with the phenoxide oxygen (1.99(1) and 2.01(1) Å) and theo-nitrogen oxygen (2.44(2) and 2.34(1) Å) of the picrates. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82037 (29 pages)     

Neutral solvent/crown ether interactions 3. Reorientation of the hydrogen bonds in the low temperature (−150°C) structure of 18-crown-6·2(CH3NO2)

The title complex was crystallized from a saturated solution of 18-crown-6 in nitromethane at 5°C and cooled to –150°C prior to X-ray diffraction data collection. At –150° C 18-crown-6·2(CH₃NO₂) is monoclinic,P2₁/_n witha=9.290(2),b=7.864(6),c=13.627(8) Å, =1000.84(4)° andD _calc=1.31 g cm^–3 for Z=2. Leastsquares refinement using 1521 independent observed reflections [F _o5(F _o)] led to a final conventionalR value of 0.041. The complex at –150°C is isostructural with its room temperature structure with the exception of the orientation of the methyl hydrogen atoms and their crown ether oxygen interactions. The methyl group hydrogen atoms were fully refined isotropically. The crown ether resides around a center of inversion and hasD _3d symmetry. There is one methyl hydrogen...crown interaction at 2.35(3) Å, one apparently bifurcated hydrogen bond utilizing a second methyl hydrogen atom (2.55(3), 2.65(3) Å) and the third hydrogen atom is actually directed away from the crown ring (closest H...O contact=2.67(3) Å). Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82048 (5 pages).For part 2, see reference [24].     

Crystal structures of heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin complexes with (R)- and (S)-Flurbiprofen

Hepatakis(2,3,6-tri-O-methyl)--cyclodextrin (TM--CDx) forms crystalline complexes with (R)-Flubiprofen (R-FP), C₆₃H₁₁₂O₃₅C₁₅H₁₃O₂F·H₂O, and (S)-Flurbiprofen (S-FP), C₆₃H₁₁₂O₃₅C₁₅H₁₃O₂F. The crystal structures were determined by X-ray analysis. Crystals of both compounds are orthorhombic and the space group isP2₁2₁2₁ with cell dimensions:a=15.092(2),b=21.714(3), andc=28.269(4) Å for theR-FP complex, anda=15.271(2),b=21.451(3) andc=27.895(3) Å for theS-FP complex. The macrocyclic ring of TM--CDx is markedly distorted because of the inability to form intramolecular hydrogen bonds and the steric hindrance involving methyl groups. In both complexes, the phenyl group is inserted into the host cavity from the O(2), O(3) side, which is wider than the O(6) side. The biphenyl moiety ofR-FP is fixed in theR-configuration within the host cavity. The phenyl group ofS-FP is disordered, andR-andS-configurations are statistically distributed with equal probability. TM--CDx molecules are stacked along theb axis to form a column structure. The TM--CDx molecule is laterally shifted with respect to the column axis, and a half of the guest molecule protrudes outside from the crevis of the column. The carboxyl group ofR-FP forms a hydrogen bond with water located outside the host cavity, while the carboxyl group ofS-FP is hydrogen-bonded to an oxygen atom of an adjacent TM--CDx. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82064 (24 pages).     

Crystallographic studies on sterically affected chemical species

The crystal and molecular structure of 2-carboxy-2-methoxybiphenyl has been determined to R=0.035. Crystals are tetragonal, of space group I4₁cd, witha=b=15.181(2)c=19.874(2) Å. Mean esd values for bond lengths and bond angles are 0.005 Å and 0.3°, respectively. The angle between phenyl rings is 54.5(1)°. The C(1) (carboxy) and O (methoxy) distance is 3.02 Å. Dimers of the title compound are hydrogen bonded with O·O distances of 2.68 Å and 2.58 Å. Due to the symmetry of the space group, the hydrogen atoms are necessarily located in the center of the O·O distance. Parameters of repulsive deformations for bond angles have been defined. Due to overcrowding in the region ofo,o-substitution, significant deformations of exocyclic bond angles have been observed. The magnitudes of these deformations depend roughly on the spatial requirements of the sterically interacting substituents, expressed by Charton's [1] parameter.     

Synthesis,structure and electrochemical properties of a dioxomolybdenum(VI) complex with a ferrocene-containing ligand

Summary Bis[ferrocene aldehyde benzoylhydrazonato(1-)-N ¹,O]- dioxomolybdenum(VI) has been synthesized and characterized by x-ray diffraction and i.r.,¹H n.m.r. and electronic spectroscopies. The CH₂Cl₂/hexane solvate crystallizes in space group P2₁/n witha=11.149(6),b=20.463(8),c= 15.541(5) Å, =90.40(3)° andZ=4. The structure has been refined to R_w=0.049 based on 2886 independent reflections. The complex has distorted octahedral geometry with the two bidentate ligands coordinated through the oxygen and the azomethine nitrogen atoms. The MoO ₂ ²⁺ unit has the expectedcis geometry and the Mo-N bonds aretrans to the oxo-groups. The chelate rings are nearly planar but the cyclopentadienyl and phenyl rings are twisted out of the chelate rings. The electrochemical behaviour of the compound is also discussed: the two ferrocenyl groups appear to be independent with respect to oxidation and the molybdenum centre displays a nearly reversible one-electron reduction.     

Die Kristallstruktur der Tieftemperaturmodifikation von Ag8GeS6

The low temperature form of Ag₈GeS₆ (synthetic argyrodite) is orthorhombic, space group Pna2₁, witha=15.149 (1),b=7.476 (2),c=10.589 (1), andZ=4. The crystal structure has been determined from 2-circle diffractometer data by means of direct methods and refined toR=0.081 for 3431 intensities. The structure consists of slightly distorted isolated GeS₄ tetrahedra (mean Ge–S bond length 2.212 Å) and two further sulphur atoms without bonds to the germanium atoms. The GeS₄ tetrahedra and the S atoms are connected by the Ag atoms to form a three-dimensional framework. Three types of Ag coordination by S atoms are encountered. Three Ag positions have a strongly distorted tetrahedral environment, four Ag positions an approximately planar threefold coordination, while one Ag atom is almost linearly coordinated by two S atoms. The Ag–S distances are 2.56–2.94 Å, 2.49–2.76 Å, and 2.42–2.44 Å, resp. All Ag atoms have at least one near Ag neighbour between 2.93 and 3.11 Å.

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Crystal structures of dibenzo-14-crown-4 alcohol and diol monohydrates

Monohydrate complexes1–3 ofsym-hydroxydibenzo-14-crown-4,sym-cis-dihydroxydibenzo-14-crown-4 andsym-trans-dihydroxydibenzo-14-crown-4, respectively, have been prepared and their solid state structures determined. For all three complexes the space group wasCmc2₁. The crystal data are: for1,a=16.256(10),b=12.076(5),c=8.767(3) Å,V=1721.0 ų withZ=4; for2,a=16.437(3),b=11.997(4),c=8.640(3) Å,V=1703.8 ų withZ=4; for3,a=16.528(7),b=12.306(3),c=8.540(3) Å,V=1737.0 ų withZ=4. The structures were refined to [R, R _w, unique data withF<n (F)]: for1, 0.066, 0.055, 828, 2.5; for2, 0.034, 0.035, 1090, 3.0; for3, 0.047, 0.036, 1038, 3.0. The three crystal structures have a high degree of isomophism and the dibenzo-14-crown-4 units in the three host-guest complexes are nearly identical. Intramolecular hydrogen bonds link an alcohol oxygen atom of the host to the oxygen atom of the guest water molecule and the oxygen atom of the guest water molecule to ether oxygen atoms of the host in1–3. In2 and3, there is an intermolecular hydrogen bond between the hydrogen atom of an alcohol group of the host and the oxygen atom of a symmetry-related water molecule guest of another complex.     

Urea-water-anion Lattices Part 1. Crystal structures of (C2H5)4N+X−·(NH2)2CO·2 H2O (X=Cl,Br, CN), an isomorphous series of layer-type inclusion complexes

The title ternary complexes (1, X=Cl;2, X=Br;3, X=CN) have been prepared and characterized by X-ray crystallography. Crystal data: space groupP2₁/n,Z=4;1,a=7.505(2),b=14.556(4),c=14.453(3) Å, =98.13(2)^o, andR _F=0.088 for 1831 observed MoK data;2,a=7.483(1),b=14.643(6),c=14.443 Å, =98.25(2)^o, andR _F=0.113 for 923 data;3,a=7.490(2),b=14.646(5),c=14.594(5) Å, =98.85(5)^o, andR _F=0.082 for 915 data. In the isomorphous crystal structure of1 and2, ordered (C₂H₅)₄N⁺ cations are sandwiched between puckered layers matching the (020) family of planes, each being constructed from the cross-linking of planar zigzag chains of hydrogen-bonded urea molecules by the water molecules and halide ions. Compound3 has the same structure except that its cyanide group is disordered. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82066 (30 pages).Operated under contract DE-AC02-76CH00016 with the U.S. Department of Energy, Office of Basic Energy Science.     

Zur Kristallchemie der Triäthanolaminkomplexe

-Sn[(OC₂H₄)₂NC₂H₄OH]₂ crystallizes with space group Pccn and cell dimensionsa=16.35 (2),b=7.26 (1),c=12.82 (1) Å andZ=4. The structure was solved by the heavy atom technique (571 observed reflections, R₁=5.9%). Tin is octahedrally coordinated by four oxygen and two nitrogen atoms (Sn–O 2.01; 2.04 Å, Sn–N 2.33 Å) of the triethanolamine molecules. The complexes possess a crystallographic two-fold axis of rotation. They are linked by hydrogen bonds, thus forming infinite chains parallel to the twofold axis.

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Neutral molecule/crown ether interactions 5. Comparison of the C−H acidic interactions of nitromethane and acetonitrile with 18-crown-6 and dibenzo-18-crown-6. Crystal structures of dibenzo-18-crown-6·2 CH3NO2 and dibenzo-18-crown-6·2 CH3CN

Complete structural characterization of dibenzo-18-crown-6·2 CH₃NO₂ and dibenzo-18-crown-6·2 CH₃CN have been carried out, including location and refinement of the methyl hydrogen atoms. Dibenzo-18-crown-6·2 CH₃NO₂ is monoclinic,P2₁/c, with (at –150°C)a=9.573(2),b=14.636(2),c=33.471(7) Å, =93.77(2)°, andD _calc=1.37 g cm^–3 forZ=8. Interactions between the solvent methyl groups and the crown ethers and other solvent nitro groups associate the 1 : 2 complexes into polymeric chains alongb. The acetonitrile adduct exists as discreet 1 : 2 complexes in the solid state with C–H...O interactions exlusively to the ether. This complex is triclinic,P 1, with (at –150°C)a=9.458(6),b=9.570(5),c=14.404(5) Å, =73.18(4), =79.85(5), =66.82(6)°, andD _calc=1.28 g cm^–3 forZ=2. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82070 (22 pages).For part 4, see reference [1].