Infinite Helical Chains Research Articles

Reaction of tellurium tetraiodide with 2,3‐dihydro‐1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene

Abstract2,3‐Dihydro‐1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene 1 (Carb, R1 = iPr, R2 = Me) reacts with TeI4 to give the carbene adduct CarbTeI2 (3). The crystal structure of 3 consists of T‐shaped monomeric fragments linked by weak Te. I interactions to form infinite helical chains. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:316–319, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20090

A novel one-dimensional helical chain polymer involving both tetra- and hexacoordinate mercury(II) ions

A new novel one-dimensional (1D) polymer involving both tetra- and hexacoordinate mercury(II) complex, [Hg 3(4,4′-bipy) 2(CH 3COO) 2(SCN) 4] n , has been synthesized and characterized. The single-crystal X-ray data of the compound show the complex to be an infinite 1D helical chain, two of the Hg atoms are four-coordinate and one is six-coordinate.

Synthesis, structure and magnetic properties of cobalt(II) and copper(II) coordination polymers assembled by phthalate and 4-methylimidazole

New coordination polymers [ M(Pht)(4-MeIm) 2(H 2O)] n ( M=Co ( 1), Cu ( 2); Pht 2−=dianion of o-phthalic acid; 4-MeIm=4-methylimidazole) have been synthesized and characterized by IR spectroscopy, X-ray crystallography, thermogravimetric analysis and magnetic measurements. The crystal structures of 1 and 2 are isostructural and consist of [ M(4-MeIm) 2(H 2O)] building units linked in infinite 1D helical chains by 1,6-bridging phthalate ions which also act as chelating ligands through two O atoms from one carboxylate group in the case of 1. In complex 1, each Co(II) atom adopts a distorted octahedral N 2O 4 geometry being coordinated by two N atoms from two 4-MeIm, three O atoms of two phthalate residues and one O atom of a water molecule, whereas the square-pyramidal N 2O 3 coordination of the Cu(II) atom in 2 includes two N atoms of N-containing ligands, two O atoms of two carboxylate groups from different Pht, and a water molecule. An additional strong O–H⋯O hydrogen bond between a carboxylate group of the phthalate ligand and a coordinated water molecule join the 1D helical chains to form a 2D network in both compounds. The thermal dependences of the magnetic susceptibilities of the polymeric helical Co(II) chain compound 1 were simulated within the temperature range 20–300 K as a single ion case, whereas for the Cu(II) compound 2, the simulations between 25 and 300 K, were made for a linear chain using the Bonner–Fisher approximation. Modelling the experimental data of compound 1 with MAGPACK resulted in: g=2.6, | D|=62 cm −1. Calculations using the Bonner–Fisher approximation gave the following result for compound 2: g=2.18, J=–0.4 cm −1.

Self-assembly of lanthanide helicate coordination polymers into 3D metal-organic framework structures.

Pyridine-2,6-dicarboxylic acid (pdcH(2) ) reacts with nitrate salts of La(III), Ce(III), and Nd(III) under hydrothermal conditions to form three-dimensional network structures, 1-4. All the compounds crystallize in the monoclinic space group P2(1)/c with the following lattice parameters: [La(2)(pdc)(3).3H(2)O] 1, a = 10.966(3) A, b = 17.534(4) A, c = 13.578(2) A, beta = 100.23(3) degrees, V( )()= 2569.3(9) A(3), Z = 4, R1 = 0.052, wR2 = 0.143, S = 1.06; [Ce(2)(pdc)(3).3H(2)O] 2, a = 12.701(3) A, b = 9.979(1) A, c = 19.401(4) A, beta = 97.73(2) degrees, V( )()= 2436.6(8) A(3), Z = 4, R1 = 0.039, wR2 = 0.117, S = 1.30; [Ce(2)(pdc)(3).3H(2)O] 3, a = 10.961(5) A, b = 17.523(5) A, c = 13.505(2) A, beta = 100.89(3) degrees, V( )()= 2547.2(8) A(3), Z = 4, R1 = 0.040, wR2 = 0.103, S = 1.08; [Nd(2)(pdc)(3).3H(2)O] 4, a = 10.944(3) A, b = 17.448(5) A, c = 13.397(2) A, beta = 101.19(3) degrees, V( )()= 2569.3(9) A(3), Z = 4, R1 = 0.052, wR2 = 0.143, S = 1.06. Compounds 1, 3, and 4 form infinite single helical chains with large widths and pitches containing four metal ions per turn while 2 forms a different helix with smaller width and pitch containing two metal ions per turn. Each helix is further bonded on either side via carboxylate bridging producing three-dimensional metal-organic framework structures.

Ni2O(L-Asp)(H2O)2)].4H2)O: a homochiral 1D helical chain hybrid compound with extended Ni-O-Ni bonding.

The hydrothermally synthesized 1D homochiral nickel aspartate oxide [Ni2O(l-Asp)(H2O)2].4H2O is based on infinite helical chains of edge- and corner-sharing nickel octahedra. It represents the first example of a chiral one-dimensional compound with an extended helical TM-O-TM subnetwork synthesized as an optically pure product. Its structure was determined ab initio by real-space methods from laboratory powder diffraction data.

Syntheses, structures, and photoluminescence of a novel class of d10 metal complexes constructed from pyridine-3,4-dicarboxylic acid with different coordination architectures.

Two novel d(10) metal coordination polymers [Zn(PDB)](n)() (1) and [Cd(3)(PDB)(2)(OH)(2)(H(2)O)(2)](n)() (2) (H(2)PDB = pyridine-3,4-dicarboxylic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TG analysis, and single-crystal X-ray diffraction. Crystal data for 1: C(7)H(3)NO(4)Zn, orthorhombic Pna2(1), a = 8.423(17) A, b = 6.574(13) A, c = 12.899(3) A, Z = 4. Crystal data for 2: C(14)H(12)N(2)O(12)Cd(3), monoclinic C2/c, a= 20.130(4) A, b = 6.692(13) A, c = 13.081(3) A, beta = 102.78(3) degrees, Z = 4. Both compounds exhibit novel three-dimensional frameworks. Compound 1 not only possesses a one-dimensional rectangular channel but also contains infinite double-stranded helical chains. Compound 2 has two different types of channels, one being built up from pyridine rings and [CdO(5)N] and [CdO(6)] building units and the other being constructed from pyridine rings and [CdO(5)N] building units. Furthermore, both compounds show strong photoluminescence properties at room temperature.

CsLa(PO3)4

The title compound, caesium lanthanum tetrametaphosphate, CsLa(PO3)4, was grown using the flux method and its structure determined by single-crystal X-ray diffraction methods. This compound is isostructural with CsNd(PO3)4. The structure is built up from infinite helical chains, (PO3)n, which are connected by isolated LaO8 dodecahedra and irregularly shaped Cs polyhedra. These chains are formed by corner-sharing of PO4 tetrahedra and run along the b axis.

Similarity between Protein–Protein and Protein–Carbohydrate Interactions, Revealed by Two Crystal Structures of Lectins from the Roots of Pokeweed

The roots of pokeweed ( Phytolacca americana) are known to contain the lectins designated PL-A, PL-B, PL-C, PL-D1, and PL-D2. Of these lectins, the crystal structures of two PLs, the ligand-free PL-C and the complex of PL-D2 with tri- N-acetylchitotriose, have been determined at 1.8 Å resolution. The polypeptide chains of PL-C and PL-D2 form three and two repetitive chitin-binding domains, respectively. In the crystal structure of the PL-D2 complex, one trisaccharide molecule is shared mainly between two neighboring molecules related to each other by a crystallographic 2 1-screw axis, and infinite helical chains of complexed molecules are generated by the sharing of ligand molecules. The crystal structure of PL-C reveals that the molecule is a dimer of two identical subunits, whose polypeptide chains are located in a head-to-tail fashion by a molecular 2-fold axis. Three putative carbohydrate-binding sites in each subunit are located in the dimer interface. The dimerization of PL-C is performed through the hydrophobic interactions between the carbohydrate-binding sites of the opposite domains in the dimer, leading to a distinct dimerization mode from that of wheat-germ agglutinin. Three aromatic residues in each carbohydrate-binding site of PL-C are involved in the dimerization. These residues correspond to the residues that interact mainly with the trisaccharide in the PL-D2 complex and appear to mimic the saccharide residues in the complex. Consequently, the present structure of the PL-C dimer has no room for accommodating carbohydrate. The quaternary structure of PL-C formed through these putative carbohydrate-binding residues may lead to the lack of hemagglutinating activity.

Two novel Zn(II) helical chain polymers containing both bridging and terminal carboxylato groups

Two novel carboxylato-bridged Zn(II) polymeric complexes [Zn(L)(CCl 3COO)] n and [Zn(L)(CF 3COO)] n , where [L=2-N-(2 ′-pyridylimine)benzoic acid] have been synthesized and structurally characterized. The structures of the two complexes are similar with the Zn(L)(Cl 3CCO 2) or Zn(L)(F 3CCO 2) units being repeated to form infinite helical chains. In each structure, the neighbouring Zn atoms are bridged sequentially by syn–anti carboxylate groups of the Schiff base.

Coordination networks generated from transition metal chlorides and a flexible double betaine

The new flexible double betaine 1,4-bis(2-picolyloxyl)benzene- N, N′-diacetate (L) has been synthesized and used to generate five complexes with divalent metal chlorides: [M(H 2O) 6]Cl 2·L·2H 2O (M=Mn ( 1), Co ( 2)), [Cu(μ-L)Cl 2] ∞ ( 3), {[Zn(μ-L)Cl 2]·2H 2O} ∞ ( 4), and {[Cd 2(μ-Cl) 2(μ-L)Cl 2(H 2O) 2]·2H 2O} ∞ ( 5). Isomorphous compounds 1 and 2 have a hydrogen-bonded three-dimensional network in which adjacent L ligands overlap through π–π stacking of the pyridine and benzene rings. Compounds 3, 4, and 5 display three different types of one-dimensional polymeric structures. Bridged by L acting in the anti mode, compound 3 exhibits an infinite zigzag chain in which consecutive, approximately planar L ligands are arranged in a crossed manner when viewed along the chain direction, the distance between adjacent copper(II) ions being about 13 Å. In contrast, compound 4 features a spring-like infinite helical chain with zinc ions lying on the axis and bridged by L acting in the syn fashion, and the Zn(II)⋯Zn(II) separation is approximately 9 Å. In compound 5, the building unit is a centrosymmetric Cd 2Cl 2 moiety, and adjacent dimeric units are linked by the centrosymmetric L ligand acting in the anti mode to give an infinite zigzag chain running along the c axis; such chains are further connected through hydrogen bonds to form a three-dimensional network.

Synthesis, Spectroscopic and Structural Aspects of Mono‐ and Diorganothallium(III) Complexes of 2, 6‐Diacetylpyridine Bis(thiosemicarbazone) (H2DAPTSC) — A New Coordination Mode of the HDAPTSC— Anion

AbstractThe reaction of 2, 6‐diacetylpyridine bis(thiosemicarbazone) (H2DAPTSC) with dimethylthallium hydroxide yielded the complexes [(TlMe2)2(DAPTSC)] and [TlMe2(HDAPTSC)]. The structure of [TlMe2(HDAPTSC)], determined by X‐ray diffractometry, exhibits a hitherto unknown coordination mode of the HDAPTSC— anion in which its deprotonated thiosemicarbazone chain coordinates one metal atom through its sulphur and hydrazinic N atoms while a second metal atom is weakly coordinated through the S atom of the undeprotonated thiosemicarbazone chain. Each thallium atom is coordinated in both ways, with the result that the [TlMe2(HDAPTSC)] units are linked in infinite helical chains in the direction of the b axis.When reacting with diphenylthallium(III) hydroxide, H2DAPTSC induced a dephenylation process which led to the monophenylthallium(III) complex [TlPh(DAPTSC)]. Recrystallization from acetone yielded crystals of [TlPh(DAPTSC)]·C3H6O in which X‐ray diffractometry showed DAPTSC2— to be pentadentate, coordinating through its sulphur, azomethine N and pyridine N atoms.The 1H, 13C and 205Tl NMR data of [TlPh(DAPTSC)] indicate that its solid state molecular structure persists in DMSO solution, while those of [TlMe2(HDAPTSC)] indicate rapid alternation between coordination of the metal atom to one of the HDAPTSC— thiosemicarbazone chains and its coordination to the other.

Design and synthesis of copper complexes of novel ligands based on the pyridine thiolate group

The versatile coordination properties of 2,2′-dipyridyldisulfide (dpds) enables a series of different copper complexes to be isolated in good yield, including [CuCl2(μ-dpds)] (1) which has a one-dimensional helical structure and [Cu(μ-Cl)(μ-dpds)] (4) which has a two-dimensional sheet structure. Flexible movement of the disulfide group in the dpds ligand facilitates the formation of complexes with a diverse range of structures. Compound 1 transforms into 4 almost quantitatively on standing in contact with methanol. After prolonged standing 4 slowly converts to the stable, betain-containing product, [Cu(μ-1-(2-pyridine)pyridiniumthiolato)(μ-Cl)] (8) with the concomitant production of elemental sulfur. The bromide congener of 4 undergoes the same transformation. The free ligand, 1-(2-pyridine)pyridiniumthiolate, can be released from 8 by treatment with CN−. On treatment of bis(2-pyridylthio)methane (BPTM) with CuCl2 [CuCl2(BPTM)]n (9) is formed. This complex has an infinite helical chain structure. Reaction between tris(2-pyridylthio)methane (TPTMH) and CuBr gave [CuBr(TPTM)] (12) and with [Cu(NCCH3)4]PF6 in the presence of oxygen, the complex [Cu(CH3CN)(TPTM)]PF6 (14) is formed. Complex 14 is the first structurally characterised example of a complex containing a Cu(II)–C(sp3) bond.

1,4-Bis(benzimidazol-2-yl)butane

The title compound, C18H18N4, lies on an inversion center. The benzimidazolyl moiety is essentially planar. Intermolecular N—H⋯N hydrogen bonds give rise to an infinite helical chain structure, with the chains stacked by C—H⋯π and π⋯π interactions.

A Chiral Lead Borate Containing Infinite and Finite Chains Built up from BO4 and BO3 Units

With a hydrothermal technique, a novel chiral lead borate (Pb6B11O18(OH)9) has been prepared. The sample has been characterized by powder X-ray diffraction, infrared spectroscopy, energy-dispersive spectroscopy, thermal analysis, and second-harmonic generation powder measurement. The structure of the compound, which crystallizes in the trigonal space group P32 with lattice constants a = 11.7691(7) A and c = 13.3361(12) A has been solved by single-crystal X-ray diffraction analysis. There exist infinite helical chains and finite chain fragments built up from BO4 and BO3 units. In the compound the Pb2+ cations are located in the space between adjacent polyborate anionic chains, compensating the negative charges of the chains. The chiral feature of the lead borate is unique, and because it lacks symmetry center, the compound exhibits distinct NLO properties.

Formation and Crystal Structure of Polymeric (MeTeCl3)n

Abstract The reaction of hexamethyldisilane with tellu­rium tetrachloride in carbon disulfide afforded polymeric (MeTeCl3)n (1) that was characterized by TOF ES mass spectroscopy, 125Te NMR spectroscopy, and X-ray crystallography. Pale brown, air-and moisture-sensitive crystals of 1 are monoclinic, space group P21/n with a = 1030.69(5), b = 643.61(2), c = 1041.68(5) pm, ß = 119.236(5)°, V = 0.60299(5) nm3, and Z = 4. The crystal structure consists of infinite helical chains of the MeTeCl3 units linked by bridging chlorine atoms. The polymeric chains are linked together by Te···Cl and Cl···Cl close contacts. The pos­sible routes for the formation of (MeTeCl3)n are discussed.

Synthesis and structure of [[Ag(SalGly)].0.33H20]n: an infinite double helical coordination polymer.

X-ray analysis of the title compound revealed infinite helical chains of [Ag(SalGly)] units (SalGly = α-N-(o-hydroxybenzyl)glycinate) linked through monatomic carboxylate bridges. In the crystal packing two unconnected helical chains wind around each other, thus forming a double helix.

Synthesis, Structure, and Magnetic Properties of Mn(salpn)N(3,) a Helical Polymer, and Fe(salpn)N(3), a Ferromagnetically Coupled Dimer (salpnH(2) = N,N'-bis(Salicylidene)-1,3-diaminopropane).

The preparation, crystal structures, and variable temperature magnetic susceptibility data are presented for two azido-bridged Schiff base complexes of Mn(III) and Fe(III). Mn(salpn)N(3) (1), where salpn is the dianion of N,N'-bis(salicylidene)-1,3-diaminopropane, crystallizes in the orthorhombic system, space group Pna2(1), with a = 11.947(2) Å, b = 11.818(2) Å, c = 11.227(5) Å, and Z = 4. Fe(salpn)N(3) (2) crystallizes in the monoclinic system, space group P2(1)/c, with a = 10.199(7) Å, b = 14.081(6) Å, c = 12.017(3) Å, beta = 105.19(3) degrees, and Z = 4. In 1, salpn coordinates in the equatorial mode, with two azide ions coordinating in axial positions. The azide ions act as "end-to-end" (&mgr;-(1,3)) bridges, leading to an infinite helical chain propagating along the crystallographic c axis. In striking contrast, 2 has a dimeric structure in which the Schiff base adopts a cis-octahedral coordination mode. The dimer is held together by two "head-on" (&mgr;-(1,1)) bridging azide ions. The polymeric compound, 1, is weakly antiferromagnetic (J = -4.03 cm(-)(1), H(ex) = -2J summation operatorS(i)()S(i)()(+1)), while 2 is weakly ferromagnetic (J = 0.76 cm(-)(1), H(ex) = -2JS(1)S(2)).

Breaking up chains: the nitridocuprates(I) Ba[CuN] Ba 16[(CuN) 8][Cu 2N 3][Cu 3N 4] and Ca 4Ba[CuN 2] 2

The three title compounds were prepared from copper or copper(I) oxide and alkaline earth metals in sodium fluxes under medium nitrogen pressures and structurally characterized. Ba[CuN] crystallizes monoclinic in C 2/c (No. 15), with Z=12, a=14.462(2) Å, b=5.5700(8) Å, c=9.478(1) Å, β=102.960(2)°. The structure contains infinite chains ∞ 1[CuN 2/2 2−], which are kinked alternately at the first and then the second nitrogen atom. Ba 16[(CuN) 8][Cu 2N 3][Cu 3N 4] crystallizes monoclinic in P2 1/c (No. 14), with Z=1, a=9.5611(4) Å, b=7.2731(2) Å, c=13.5225(5) Å, β=93.115(2)°. It is build from infinite helical chains ∞ 1[CuN 2/2 2−] separated by discrete linear [Cu 2N 3] 7− and Z-shaped [Cu 3N 4] 9− ions. Ca 4Ba[CuN 2] 2 crystallizes tetragonal in P 4/ncc (No. 130), with Z=4, a=8.2366(4) Å, c=12.5731(6) Å. In this compound the nitridocuprate ions are broken down to isolated linear units [CuN 2] 5−.

Crystal structure of (22R)-6α,9α-difluoro-11β,21-dihydroxy-16α,17α-propylmethylenedioxypregn-4-ene-3,20-dione · 2-propanol (4:1) solvate, C25H34O6F2 · 1/4(C3H8O)

Abstract In the course of our search for new anti-inflammatory glucocorticosteroids with improved therapeutic index, the 6α,9α-difluoro-11β,21-dihydroxy-16α,17α-propylmethylenedioxypregn-4-ene-3,20-dione was synthesised, and the conformation, configuration and crystallisation behaviour of one of its C(22) epimers, rofleponide, was studied by X-ray single-crystal diffraction. The crystals, grown from a 2-propanol solution, had a body-centred tetragonal (I4, No. 79) unit cell with a = b = 27.952(2) Å, c = 6.3299(3) Å, V c = 4945.6(6) Å3, D c = 1.2989(2) g cm−3 and F(000) = 2064, containing eight steroid and two solvent molecules. The alcoholic guest molecules were found to be disordered, each one occupying two partly overlapping disorder positions with equal probability. The structure model was refined to R = 0.045 for 1199 observations with I > 2σ(I). The basic cyclopentanoperhydrophenanthrene steroid skeleton, containing four (A, B, C and D) rings, has a flat shape with the trans-anti-trans-anti-trans stereochemistry, like the naturally occurring steroid hormones. The dioxolane (E) ring is fused to the cyclopentane (D) ring (at the 16α, 17α-positions) in a cis manner, with the angular hydroxyacetyl substituent at C(17) approximately equatorially oriented to the D and axially to the E rings, and with the C(22)-propyl chain equatorially attached to the dioxolane ring. Hence, the stereogenic centre at C(22), created during the formation of the cyclic 16α,17α-acetal, has the absolute R configuration. The rofleponide molecules in the crystal are linked via hydrogen bonds [O(21) ⋯ HO(3)] into infinite helical chains winding around the four-fold screw axes. The helices are tied to each other by additional hydrogen bonds [O(11) ⋯ HO(20)], thus forming a three-dimensional H-bonded framework. This packing arrangement is stabilised by inclusion of the 2-propanol solvent, yielding a singular type of ‘tubulato clathrate’, where the alcoholic guests reside in channel-like cavities not inside but between the host helices without any noticeable interaction with the steroid molecules.

Article

The crystal structure of 3,4,7,8-tetramethylglycoluril (5) was determined by X-ray diffraction. The structure reveals a hydrogen-bonding motif in the crystal lattice that differs from that present in related glycolurils. The two sides of each molecule form part of two independent, but parallel, infinite helical chains. These chains are formed by the NH donor and C==O acceptor on one side of a glycoluril molecule, forming H-bonds to two different molecules at adjacent positions within the helix. On the other side of the same molecule, a similar motif generates another helix of opposite helicity to the first. The molecule has a crystallographic plane of symmetry through the two bridgehead carbon atoms and the two bridgehead methyl groups, which are syn-periplanar. Thus, 5 is similar to 3,4-dimethylglycoluril (3), but differs from some glycolurils, where there is a significant dihedral angle between the two bridgehead-to-bridgehead substituent bonds. Bond lengths and angles in 5 resemble those reported for 3, but bond lengths around the bridgehead positions are slightly lengthened relative to 3.Key words: glycoluril, 1,2,5,8-tetramethyl-2,6,7,8-tetraazabicyclo[3.3.0]octane-3,7-dione, X-ray diffraction, crystal structure, hydrogen-bond array.