The organic ligands as template: the synthesis, structures and properties of a series of the layered structure rare-earth coordination polymers

A series of new 2D-layered structural rare-earth coordination polymers with the general formal [Ln(C₈H₄O₅)(H₂O)₅]·(H₂O)·(C₈H₄O₅)_1/2 (Ln=Eu for (1); Gd for (2); Tb for (3); Dy for (4); and Er for (5)) have been yielded by hydrothermal synthesis. The coordination polymers crystallize in monoclinic space group C/2c with a=19.838(16), b=10.529(8), c=17.752(14) Å, β=107.503(14)° for (1), with a=19.823(7), b=10.552(4), c=17.762(6) Å, β=107.443(6)° for (2), with a=19.770(4), b=10.519(2), c=17.698(4) Å, β=107.52(3)° for (3), with a=19.632(2), b=10.492(2), c=17.617(3) Å, β=107.470(12)° for (4), with a=19.648(7), b=10.480(3), c=17.598(6) Å, β=107.502(6)° for (5), respectively. And the metal ions (Ln³⁺) are located in nine-member coordination environment. The carboxyl groups from 5-hydroxyisophthalate chelate the metal ions to form 1D helical cation chains. It is interesting that these helical cation chains are arranged to form 2D anion–cation layers by the uncoordinated ligands' anions as template. And the luminescence properties of the rare-earth ions are studied in the paper.     

Structural and spectral studies of N-2-(pyridyl)-, N-2-(3-, 4-, 5-, and 6-picolyl)- and N-2-(4,6-lutidyl)-N′-2-thiomethoxyphenylthioureas

Structures of the following compounds have been obtained: N-(2-pyridyl)-N′-2-thiomethoxyphenylthiourea, PyTu2SMe, monoclinic, P2₁/c, a=11.905(3), b=4.7660(8), c=23,532(6) Å, β=95.993(8)°, V=1327.9(5) ų and Z=4; N-2-(3-picolyl)-N′-2-thiomethoxyphenyl-thiourea, 3PicTu2SeMe, monoclinic, C2/c, a=22.870(5), b=7.564(1), c=16.941(4) Å, β=98.300(6)°, V=2899.9(9) ų and Z=8; N-2-(4-picolyl)-N′-2-thiomethoxyphenylthiourea, 4PicTu2SMe, monoclinic P2₁/a, a=9.44(5), b=18.18(7), c=8.376(12) Å, β=91.62(5)°, V=1437(1) ų and Z=4; N-2-(5-picolyl)-N′-2-thiomethoxyphenylthiourea, 5PicTu2SMe, monoclinic, C2/c, a=21.807(2), b=7.5940(9), c=17.500(2) Å, β=93.267(6)°, V=2893.3(5) ų and Z=8; N-2-(6-picolyl)-N′-2-thiomethoxyphenylthiourea, 6PicTu2SMe, monoclinic, P2₁/c, a=8.499(4), b=7.819(2), c=22.291(8) Å, β=90.73(3)°, V=1481.2(9) ų and Z=4 and N-2-(4,6-lutidyl)-N′-2-thiomethoxyphenyl-thiourea, 4,6LutTu2SMe, monoclinic, P2₁/c, a=11.621(1), b=9.324(1), c=14.604(1) Å, β=96.378(4)°, V=1572.4(2) ų and Z=4. Comparisons with other N-2-pyridyl-N′-arylthioureas having substituents in the 2-position of the aryl ring are included.     

Preparation and crystal structure of a 1:1 inclusion compound of 1,4,11,14-tetramethoxy-dibenzo[b,n]tetraphenylene with pyridine

The new host 1,4,11,14-tetramethoxy-dibenzo[b,n]tetraphenylene forms a 1:1 inclusion compound with pyridine, in which a pair of centrosymmetrically-related guest species are enclosed in the cage surrounded by six host molecules. C₃₆H₂₈O₄·C₅H₅N, F_W=603.68, triclinic, space group P-1, a=11.796(2), b=16.075(3), c=9.004(2) Å; =98.39(3)°, β=90.01(3)°, γ=108.19(3)°, V=1602.8(5) Å³, Z=2, F(000)=636, D_c=1.251 g/cm³, μ=0.080 mm⁻¹. The final R indices [I>2σ(I)] R₁=0.0759, wR₂=0.1970 for 5623 MoK observed data.     

Structural, spectral and thermal studies of N-2-(4-picolyl)- and N-2-(6-picolyl)-N′-(2-chlorophenyl)thioureas and N-2-(6-picolyl)-N′-(2-bromophenyl)thiourea

N-2-(4-picolyl)-N′-2-chlorophenylthiourea, 4PicTu2Cl, monoclinic, P2₁/c, a=10.068(5), b=11.715(2), β=96.88(4)°, and Z=4; N-2-(6-picolyl)-N′-2-chlorophenylthiourea, 6PicTu2Cl, triclinic, P-1, a=7.4250(8), b=7.5690(16), c=12.664(3) Å, =105.706(17), β=103.181(13), γ=90.063(13)°, V=665.6(2) ų and Z=2 and N-2-(6-picolyl)-N′-2-bromophenylthiourea, 6PicTu2Br, triclinic, P-1, a=7.512(4), b=7.535(6), c=12.575(4) Å, a=103.14(3), β=105.67(3), γ=90.28(4)°, V=665.7(2) ų and Z=2. The intramolecular hydrogen bonding between N′H and the pyridine nitrogen and intermolecular hydrogen bonding involving the thione sulfur and the NH hydrogen, as well as the planarity of the molecules, are affected by the position of the methyl substituent on the pyridine ring. The enthalpies of fusion and melting points of these thioureas are also affected. ¹H NMR studies in CDCl₃ show the NH′ hydrogen resonance considerably downfield from other resonances in their spectra.     

Studies of π-bonding perturbation in the tungsten-nitrogen multiple bond of isopropylimido tungsten(VI) complexes: The crystal and molecular structures of [W(NCHMe2)Cl4]2·C6H6 and [W(NCHMe2)Cl5][NEt4]

¹³C NMR chemical shift data for the -carbon (δ) of a variety of tungsten isopropylimido complexes indicate that the extent to which the nitrogen lone pair participates in multiple bonding to tungsten depends on the form of the complex and the ligands involved. The structures of [W(NCHMe₂)Cl₄]₂·C₆H₆ (1a) and [W(NCHMe₂)Cl₅][NEt₄] (7) which show widely different δ values, have been determined by single-crystal X-ray diffraction methods. Crytals of 1a are triclinic space group P , with a = 6.394(2), b = 8.890(3), c = 11.205(2) Å and = 109.95(2)°, β = 98.91(2)°, γ = 93.96(2)°; crystals of 7 are orthorhombic, space group Pnma, with a = 13.667(5), b = 15.152(2), c = 9.432(2) Å. Both structures were solved by Patterson and Fourier methods and refined to an R value of 0.050 for 1325 observed data of 1a and to an R value of 0.050 for the 1157 observed data of 7. Complex 1a is dimeric with a W---N bond length of 1.697(12) Å and complex 7 is monomeric with a longer W---N bond length of 1.763(16) Å. Comparison of the W---Cl bond lengths and correlations with π-bonding to make an 18-electron count, indicates that the W---N bond lengths differ in the two complexes as a result of overall π-bonding requirements.     

A survey of the lone pair effect on the ring geometry of 1,2,4-triazoles and analogous 1,2,3-triazoles and imidazoles : The structures of 1-methyl-5-amino-3-methylthio-1,2,4-triazole, 1-phenyl-5-amino-3-methylthio-1,2,4-triazole and 1-(4-methylbenzyl)-3-amino-5-methylthio-1,2,4-triazole

The structures of the title compounds have been established by X-ray crystallography from diffractometer data. Crystals of the first (I), C₄H₈N₄S, are monoclinic, space group P2₁/c, with a = 8.166(2), b = 10.481(1), c = 8.585(1) Å, β = 109.33(2)°, Z = 4, D_c = 1.381 g cm⁻³. Crystals of the second (II), C₉H₁₀N₄S, are monoclinic, space group P2₁/c, with a = 11.850(4), b = 7.898(1), c = 23.981 (6) Å, β = 117.23(2)°, Z = 8, D_c = 1.373 g cm⁻³. Crystals of the third (III), C₁₁H₁₄N₄S₁ are also monoclinic, space group P2₁/c with a = 12.829(3), b = 8.348(1), c = 11.088(4) Å, β = 94.40(4)°, Z = 4, D_c = 1.314 g cm⁻³. The structures, determined by direct methods (I, III) and Patterson synthesis (II) were refined to R = 0.039 for 1070 reflections of I, R = 0.040 for 2792 reflections of II and R = 0.041 for 1900 reflections of III. The characteristic features of the planar five-membered rings are studied in comparison with the analogous 1,2,3-triazoles and imidazoles. It is shown that these planar rings exhibit only two patterns of the endocyclic bond angles induced dominantly by the number and relative position of the N-lone pairs. A similar effect of the double bonds (attached to C atoms) is also discussed.     

Bilayer structure of tetrasodium thiacalix[4]arene tetrasulfonate

The title calixarene, tetrasodium thiacalix[4]arene tetrasulfonate, was prepared and its crystal structure was determined. Na₄[thiacalix[4]arene sulfonate]·9H₂O·CH₃CH₂OH, belongs to triclinic system, space group P , a=10.820(5), b=14.109(6), and c=14.514(6)Å, =99.702(7), β=93.445(8), and γ=93.445(8)°, V=2174.2(16)ų, Z=2. The title calixarene exists in the solid state as bi-layer of anionic calixarene in the cone configuration. These layers alternate with inorganic regions which contain the sodium cations and the water molecules.     

The crystal structures at 80 K and IR spectra of the complex of 4-methylpyridine with pentachlorophenol and its deuterated analogue

The crystal structures of the complex of 4-methylpyridine with pentachlorophenol (MP-PCP) and its deuterated analogue (MP-PCP-d) were determined at 80 K by X-ray diffraction. The MP-PCP complex crystallizes in the space group P with a = 7.267(7), b = 8.966(9), c = 13.110(14)Å, = 99.70(8), β = 118.16(9), γ = 103.38(8)° and Z = 2 and the MP-PCP-d complex in the monoclinic Cc space group with a = 3.826(2), b = 27.54(2), c = 13.209(12)Å, β = 101.38(9)° and Z = 4. The O… H … N bridge bond distance of 2.515(4) Å is significantly shorter than that determined at room temperature (2.552(4) Å) and the O---D … N bond length of 2.628(6) Å is only slightly shorter than at room temperature (2.638(3) Å). The temperature dependence of the IR spectra confirms the symmetrization of the OHN hydrogen bond.     

The crystal structures at 80 K and IR spectra of the complex of 4-methylpyridine with pentachlorophenol and its deuterated analogue

The crystal structures of the complex of 4-methylpyridine with pentachlorophenol (MP---PCP) and its deuterated analogue (MP---PCP-d) were determined at 80 K by X-ray diffraction. The MP---PCP complex crystallizes in the space group with a = 7.267(7), b = 8.966(9), c = 13.110(14) Å, = 99.70(8), β = 118.16(9), γ = 103.38(8)° and Z = 2 and the MP---PCP-d complex in the monoclinic Cc space group with a = 3.826(2), b = 27.54(2), c = 13.209(12) Å, β = 101.38(9)° and Z = 4. The O…H…N bridge bond distance of 2.515(4) Å is significantly shorter than that determined at room temperature (2.552(4) Å) and the O---D…N bond length of 2.628(6) Å is only slightly shorter than at room temperature (2.638(3) Å). The temperature dependence of the IR spectra confirms the symmetrization of the OHN hydrogen bond.     

The system CePO4–K3PO4

The phase diagram of the system CePO₄–K₃PO₄ has been determined based on investigations by differential thermal analysis, X-ray powder diffraction, IR spectroscopy and optical microscopy. The system contains only one intermediate compound K₃Ce(PO₄)₂, which melts incongruently at (1500±20)°C. This compound is stable down to room temperature and exhibits a polymorphic transition at 1180°C. It was confirmed that the low-temperature form β-K₃Ce(PO₄)₂ crystallizes in a monoclinic system, space group P2₁/m with unit cell parameters a=9.579 (5), b=5.634 (6), c=7.468 (5) Å; =γ=90°, β=90.81 (3)°; V=403.083 Å³.     

Syntheses and crystal structures of 1,2:5,6:9,10:13,14:17,18:21,22-hexabenzo-3,7,11,15,19,23-hexadehydro[24]annulene (HBC), 1,2:5,6:9,10:13,14-tetrabenzo-3,7,11,15-tetradehydro[16]annulene (QBC) and a tetracobalt complex of QBC. The first example of a transition metal complex of QBC

1,2:5,6:9,10:13,14-Tetrabenzo-3,7,11,15-tetradehydro[16]annulene, or tetrabenzocyclyne (QBC) and 1,2:5,6:9,10:13,14:17,18:21,22-hexabenzo-3,7,11,15,19,23-hexadehydro[24]annulene (HBC) have been structurally characterized by X-ray. crystallography. QBC crystallizes in two different space groups; P2₁/c with a = 10.652(3) Å, b = 10.624(2) Å, c = 19.549(4) Å, β = 93.83(2)°, V = 2207.4(8) ų, and Z = 4 and P4₁2₁2 with a = 9.330(1) Å, c = 25.497(8) Å, V = 2219.6(12) Å, and Z = 4. HBC crystallizes in monoclinic P2₁/n with a = 14.763(3) Å, b = 10.296(2) Å, c = 22.057(4) Å, β = 108.61(3), V = 3177.4(11) ų, T = 133 K, and Z = 4. Reaction of QBC with dicobaltoctacarbonyl has produced a tetracobalt complex which has been characterized by X-ray crystallography. This complex crystallizes in monoclinic P2₁/c with a = 14.699(3) Å, b = 17.188(3) Å, c = 17.254(3) Å, β = 112.63(3)°, V = 4023.5(13) ų, and Z = 4. Only two of the four C---C triple bonds of QBC bind to dicobalthexacarbonyl moieties even when excess dicobaltoctacarbonyl is used.     

The cyclopalladation of benzylidenebenzylamines

A number of isomeric N-benzylbenzalimine palladium(II) complexes of the type [P ·CH₂Ph]₂ (with C=N endo to the palladocycle) and [P =C(CH₃Ph]₂ (with C=N exo to the palladocycle), have been prepared and charcterised by ¹H and ¹³C NMR methods. The crystal structures of two analogous monomeric acac complexes, synthesized independently by oxidative addition of o-BrC₆H₄CH₂N=CH · Ph to Ph to Pd(dibenzylideneacetone)₂ have also been determined. These are [P · CH₂Ph)] (15a) and [P =CHPh)] (20a). Crystals of 15a are monoclinic, space group P2₁/a with Z = 4 in a cell of dimensions a 10.286(2), b 11.902(3), c 13.895(5) Å, β 93.52(2)° while 20a is monoclinic, space group P2₁/c with Z = 8 and a 10.353(3), b 20.600(5), c 16.545(7) Å, β 92.14(3)°. The structures 15a and 20a were refined to residuals R = 0.041 and 0.055 for 1661 and 2525 observed reflections respectively.     

Copper(I) coordination compounds with two bidentate chelating pyrazole ligands. X-ray crystal structures of DI-μ-chloro-bis[[N,N-bis(1- pyrazolylmethyl)aminoethane]copper(I)] and [bis(N,N-bis(1-pyrazolylmethyl)aminoethane]copper(I) triflate

The pyrazole derivatives of aminoethane N,N-bis(3,5-dimethyl-1-pyrazolyl- methyl)aminoethane (aebd) and N,N-bis(1-pyrazolylmethyl)aminoethane (aebp) form co- ordination compounds with copper(I) of stoichiometry [Cu(L)X], with X = Cl, Br, I and SCN, and [Cu(L)₂X], with X = CF₃SO₃ and BF₄. The ligands chelate in a bidentate manner, with only the pyrazole groups coordinating. The crystal structures of two representative examples have been determined: [Cu(aebp)Cl]₂ is triclinic, space group P , with a = 8.711(2), b = 9.351(1) and c = 9.528(1) Å, = 68.57(1)°, β = 61.47(1)° and γ = 77.82(1)°, and Z = 2. Standard least-squares refinement gave R = 0.029 (R_w = 0.038) for 1804 reflections. [Cu(aebp)₂]CF₃SO₃ is monoclinic, space group P2₁/n, with a = 13.352(5), b = 14.663(3) and c = 15.752(4) Å, β = 117.49(3)°, and Z = 4. Standard least-squares refinement gave R = 0.029 (R_w = 0.032) for 1786 reflections. In both cases the copper environment is slightly-distorted tetrahedral. The chloride compound is dimeric with one ligand molecule (Cu---N distances of 2.011(2) and 2.047(2) Å) and two bridging chlorides per copper (Cu---Cl distances of 2.3874(8) and 2.4094(8) Å). With the non- coordinating triflate anion, a monomeric compound with two ligand molecules per copper was obtained (Cu---N distances of 2.018(4), 2.028(4), 2.049(4) and 2.050(4) Å).     

Hydrogen bonds in the crystal packings of mesalazine and mesalazine hydrochloride

The crystal structures of pharmaceutical product mesalazine (marketed also under different proprietary names as Salofalk, Asacol, Asacolitin, and Claversal) and its hydrochloride are reported. In the crystal mesalazine is in zwitterion form as 5-ammoniosalicylate (1) whereas mesalazine hydrochloride crystallizes in an ionized form as 5-ammoniosalicylium chloride (2). Compound 1 (C₇H₇O₃N) crystallizes in the monoclinic space group P2₁/n with a = 3.769(1) Å, b = 7.353(2) Å, c = 23.475(5) Å, β = 94.38(2)°, V = 648.7(8) ų, Z = 4, D_c = 1.568 g cm⁻³ and μ(MoK) = 1.2 cm⁻¹. Compound 2 (C₇H₈O₃NCl) crystallizes in the triclinic space group P with a = 4.4839(2) Å, b = 5.7936(2) Å, c = 15.6819(5) Å, = 81.329(3)°, β = 88.026(3)°, γ = 79.317(4)°, V = 395.74(3) ų, Z = 2, D_c = 1.591 g cm⁻³ and μ(CuK) = 40.8 cm⁻¹. The crystal structures were solved by direct methods and refined to R = 0.041 for 1 and 0.028 for 2, using 607 and 1374 observed reflections, respectively. The configuration of both molecules, with the ortho hydroxyl to a carboxyl group, favours the intramolecular hydrogen bonds. Very complex systems of intermolecular hydrogen bonds were observed in both crystal packings. They are discussed in terms of graph-set notation. The mesalazine crystal structure is characterized by two-dimensional network of hydrogen bonds in the ab plane. The crystal structure pattern of mesalazine hydrochloride is a three-dimensional network significantly supported by N⁺---HCl⁻ interactions.     

Structural and theoretical studies of Xe(OChF5)2 and [XeOChF5][AsF6] (Ch = Se, Te)

The XeOSeF₅⁺ cation has been synthesized for the first time and characterized in solution by ¹⁹F, ⁷⁷Se and ¹²⁹Xe NMR spectroscopy and in the solid state by X-ray crystallography and Raman spectroscopy with AsF₆⁻ as its counter anion. The X-ray crystal structures of the tellurium analogue and of the Xe(OChF₅)₂ derivatives have also been determined: [XeOChF₅][AsF₆] crystallize in tetragonal systems, P4/n, a=6.1356(1) Å, c=13.8232(2) Å, V=520.383(14) Å³, Z=2 and R₁=0.0453 at −60°C (Te) and a=6.1195(7) Å, c=13.0315(2) Å, V=488.01(8) Å³, Z=2 and R₁=0.0730 at −113°C (Se); Xe(OTeF₅)₂ crystallizes in a monoclinic system, P2₁/c, a=10.289(2) Å, b=9.605(2) Å, c=10.478(2) Å, β=106.599(4)°, V=992.3(3) Å³, Z=4 and R₁=0.0680 at −127°C; Xe(OSeF₅)₂ crystallizes in a triclinic system, , a=8.3859(6) Å, c=12.0355(13) Å, V=732.98(11) Å³, Z=3 and R₁=0.0504 at −45°C. The energy minimized geometries and vibrational frequencies of the XeOChF₅⁺ cations and Xe(OChF₅)₂ were calculated using density functional theory, allowing for definitive assignments of their experimental vibrational spectra.     

Cation–anion interactions in triphenyl telluronium salts. The crystal structures of (Ph3Te)2[MCl6] (M=Pt, Ir), (Ph3Te)[AuCl4], and (Ph3Te)(NO3)·HNO3

Triphenyltelluronium hexachloroplatinate (1), hexachloroiridate (2), tetrachloroaurate (3), and tetrachloroplatinate (4) were prepared from Ph₃TeCl and potassium salts of the corresponding anions. Upon recrystallization of 4 from concentrated nitric acid, K₂[PtCl₆] and (Ph₃Te)(NO₃)·HNO₃ (5) were obtained. The crystal structures of 1–3 and 5 are reported. Compounds 1 and 2 are isostructural. They are triclinic, P , Z=2 (the asymmetric unit contains two formula units). Compound 1: a=10.7535(2), b=17.2060(1), c=21.4700(3) Å, =78.9731(7), β=77.8650(4), γ=78.8369(4)°. Compound 2: a=10.7484(2), b=17.1955(2), c=21.4744(2) Å, =78.834(1), β=77.649(1), γ=78.781(1)°. Compound 3 is monoclinic, P2₁/c, Z=4, a=8.432(2), b=14.037(3), c=17.306(3) Å, β=93.70(3)°. Compound 5 is monoclinic. P2₁/n, Z=4, a=9.572(2), b=14.050(3), c=13.556(3) Å, β=90.76(3)°. The primary bonding in the Ph₃Te⁺ cation in each salt is a trigonal AX₃E pyramid with Te---C bond lengths in the range 2.095(8)–2.14(2) Å and the bond angles 94.1(6)–100.9(5)°. The weak TeCl (1–3) and TeO (5) secondary interactions expand the coordination sphere. In 1 and 2 the cation shows a trigonal bipyramidal AX₃YE coordination with one primary Te---C bond and the shortest secondary TeCl contact in axial positions and the two other Te---C bonds and the lone-pair in equatorial positions. The cation in 3 shows a distorted octahedral AX₃Y₃E environment and that in 5 is a more complex AX₃Y₃Y′₂ arrangement. In both latter salts the structure is a complicated three-dimensional network of cations and anions.     

Synthesis and X-ray crystal structures of rac- and meso-2,2′-propylidene-bis(1-indenyl) zirconium dichlorides

An improved synthesis of 2,2′-bis(1-indenyl)propane and the corresponding ansa-complexes of zirconium are reported. Synthesis of a mixture of rac- and meso-2,2′-propylidene-bis(1-indenyl)zirconium dichlorides involves a treatment of ZrCl₄ with bis[3-(trialkyltin)inden-1-yl]propane, where alkyl = ethyl, butyl, in toluene. This reaction gives the products in 92% yield and might be a convenient synthetic pathway to a number of straightforward ansa-metallocenes. Both rac- and meso-2,2′-propylidene-bis(1-indenyl)zirconium dichlorides were separated and isolated using simple work-up processes, and characterized by X-ray crystal structure analysis (rac:C2/c; a = 15.903(3) Å, b = 11.105(2) Å and c = 11.520(2) Å; β = 121.61(3)°; Z = 4; V = 1732.6(5) ų; R = 0.0350; meso-: P1¯; a = 9.739(2) Å, b = 12.798(4) Å and c = 15.322(4) Å; = 101.18(2)°; β = 121.61(2)°; γ = 90.54(2)°, Z = 4; V = 1795.4(8) ų; R = 0.0417).     

Crystal and molecular structure of Δ-5,6-diphenyl-5-methoxy-1,2,4-triazacyclohexene-3-thione and Δ-4-methyl-5,6-diphenyl-5-ethoxy-1,2,4-triazacyclohexene-3-thione

Condensation of thiosemicarbazide or N(4)-ethylthiosemicarbazide with 1,2,8,9-tetraphenyl-3,7-diazanona-1,9-dione in the presence of copper(II) acetate in 96% ethanol leads to Δ⁶-5,6-diphenyl-5-methoxy-1,2,4-triazacyclohexene-3-thione, C₁₆H₁₅N₃OS, or Δ⁶-4-methyl-5,6-diphenyl-5-ethoxy-1,2,4-triazacyclohexene-3-thione, C₁₈H₁₉N₃OS. For C₁₆H₁₅N₃OS the crystal data are monoclinic, P2₁/c, a=9.7780(7), b=8.5120(3), c=18.2210(13) Å, β=100.958(3)°, V=1488.89(16) ų, and Z=4 in agreement with an earlier report. For C₁₈H₁₉N₃OS the crystal data are orthorhombic, P2₁2₁2₁, a=8.6940(3), b=12.9946(3), c=15.5139(5) Å, V=1752.68(9) ų, and Z=4.     

X-ray study of the hetero ring flexibility in trans-5,6- trimethylene- and tetramethylene-5,6-dihydro 2-phenyl-[4H]-1,3-thiazines

The structures to two 1,3-thiazine derivatives differing only in the number of CH₂ groups in their trans fused hydrocarbon ring (_n = 3 for I and n = 4 for II) have been established by X-ray crystallography from diffractometer data. Crystals of I (trans-5,6- trimethylene-5,6-dihydro-2-phenyl-[4H] - 1,3-thiazine) are triclinic, space group P with a = 7.661(1), b = 8.282(1), c = 9.566(2) Å, = 91.75(1), β = 100.72(1), γ = 105.45(1)° Z = 2, D_c = 1.260 g cm^-3. Crystals of II (trans-5,6-tetramethylene-5,6-dihydro-2-phenyl [4H]-1,3-thiazine) are monoclinic, space group P2₁/c with a = 7.914(2), b = 19.362(13), c = 8.440(1) Å, β = 109.16(2)°C Z = 4, D_c = 1.258 g cm^-3. The structures determined by Patterson (I) and direct (II) methods were refined to R = 0.050 for 1330 reflections of I and R = 0.082 for 1012 reflections of II. The proper treatment of the positional disorder of the carbon atoms (C(5) and C(6)) forming the trans ring junction in I discovered two discrete conformations with a ratio of 1:2. The opposite chirality of atoms C(51) and C(52), and C(61) and C(62), indicates a simultaneous configurational disorder with a pattern of total disorder: A A . The puckering parameters of the hetero rings in the same enantiomers of molecules IA, IB and II indicate a connection between the conformers: ⁵E(II)→⁵H₆(IB)→E₆IA) via pseudorotation. Their relationship is discussed and compared with the conformational freedom of the analogous 1,3-oxazine derivatives.     

Hydrogen bonds in 4-dihydroxymethylpyridinium 2,6-dichloro-4-nitrophenolate

The ionic adduct of 2,6-dichloro-4-nitrophenol with 4-formylpyridine (which transforms into 4-dihydroxymethylpyridine), crystallizes in the space group P2₁/c with a = 12.264(2), b = 6.730(1), c = 16.731(3) Å, β = 99.46(3)° and Z = 4. Relatively long N⁺---HO⁻ hydrogen bonds (R_N = 2.683(3) Å are formed with strongly asymmetric location of the H-atom. This is well reflected both in IR and UV-VIS spectra. One of the gem diol OH group is attached to the phenolate oxygen atom and the second is engaged in the formation of infinite polyanionic chains via O---HO hydrogen bonds between OH groups.