Mesophase design: II. Molecular structure and crystal packing of 4-alkyloxycyanobiphenyls

A joint analysis of the molecular geometry and crystal packings of the members of a homologous series of 4-alkyloxycyanobiphenyl C _n H_{2n + 1}-O-C₆H₄-C₆H₄-CN with n = 5–12 does not reveal a direct relationship between the molecular geometry and mesogenic properties of these compounds. The crystal packings of all of them are built from alternating loose aliphatic and dense aromatic regions. The closely packed aromatic regions of crystals exhibit weak intermolecular directed interactions of different natures which are responsible for the occurrence of the mesophase. The type of mesophase depends on the number s of structure-forming elements, the ratio of their energies (if s > 1), and the melting temperature of the compound. A graph system is used to describe the crystal packings and the mesophase. It is shown that, although the mesophase graph is similar to the crystal graph, they may differ somewhat, because some symmetric limitations (for example, lattice) on the molecular associate structure are removed in the melt.     

Molecular and crystal structure of 4-hexylbenzoic acid: Design of the mesophase

The crystal structure of 4-hexylbenzoic acid C₆H₁₃-C₆H₄-COOH, which forms a nematic mesophase upon melting, is determined. The crystal contains three crystallographically independent molecules. Their molecular skeletons are made up of two almost planar fragments: a benzene ring, π-conjugated with the carboxyl group and a planar zigzag aliphatic fragment. One of the independent molecules forms centrosymmetric dimers via pairs of hydrogen bonds between carboxyl groups, whereas the two others are linked via hydrogen bonds. The dimers in the crystal are packed into pseudostacks with a pronounced nonparallel arrangement of conjugated fragments. There is no good mutual projecting of benzene rings in the stacks, which corresponds to efficient π-stacking interaction. The graph describing the mesophase of this compound contains only one structure-forming element (a hydrogen bond) and corresponds to the nematic mesophase.     

Molecular and crystal structures of 4-acylphenyl 4′-alkyloxybenzoates

The crystal structures of four liquid-crystal (LC) compounds belonging to 4-acylphenyl 4′-alkyloxybenzoates with the general formula C _n H_{2n + 1}-C(O)-C₆H₄-O-C(O)-C₆H₄-O-C _m H_{2m + 1} numbered as 1/6, 1/7,2/7, and 3/7 (the numbers in the code indicate the ratios of the numbers of alkyl-chain units, n/m) are determined. Compounds 1/6 and 1/7 form smectic and nematic phases, but they are monotropic mesogens, whereas compounds 2/7 and 3/7 form only an enantiotropic smectic phase. Compound 3/7 crystallizes in two crystal modifications—triclinic with Z′ = 2 (3/7 _tr ) and monoclinic with Z′ = 4 (sp. gr. P2, 3/7 _mon ). All crystals consist of alternating aromatic and aliphatic regions and are characterized by the presence of weak directional interactions, such as C-H...O hydrogen bonds and π-stacking interactions. This provides the necessary conditions for the formation of a mesophase, and the existence of two types of structure-forming units is in line with the formation of a smectic phase. An explanation is proposed for the monotropic properties of 1/6 and 1/7.     

Liquid Crystalline Phases in 4-Acetyl-4′-n-Alkanoyloxy-Azobenzenes

Abstract

The preparation and melting behaviour of the homologous series of 4-acetyl-4′-n-alkanoylox-azobenzenes, CH₃-CO-C₆H₄-N?N-C₆H₄-O-CO-(CH₂) _n -CH₃, (with n ranging from zero to 16) is reported. The melting behaviour has been investigated by means of thermal microscopy and differential scanning calorimetry. The experimental results indicate for almost all the compounds the presence of solid state polymorphism and a type A smectic; for one compound a type B smectic phase is also present. Some homologs present, in addition, a nematic phase.     

Molecular and crystal structure of 4-alkoxybenzoic acids: Design of the mesogenic phase

The crystal and molecular structures of 4-alkoxybenzoic acids C _n H_{2n + 1}-O-C₆H₄-COOH, n = 4–12, which are nematic (n = 4–6) or smectic-nematic (n = 7–12) mesogenes, are studied. No direct relationship between the molecular geometry and mesogenic properties is found. All the crystal structures contain dimers formed by pairs of O…H-O hydrogen bonds between carboxyl groups. Crystals belonging to the group of smectic-nematic liquid crystals (SNLC) are built of separate regions, namely, loosely packed aliphatic regions and closely packed aromatic regions with significant π-stacking interactions. Loose aliphatic regions occur in crystals belonging to the group of nematic liquid crystals (NLC); however, they are surrounded by dense aromatic regions and do not run throughout the crystal. In NLC, π-stacking interactions are far weaker than in SNLC. At the early stage of melting of SNLC crystals, structurized associates due to both π-stacking interactions and hydrogen bonds are retained in the melt (smectic phase), whereas, upon further heating, only hydrogen-bonded associates are left (nematic phase). In the course of melting of NLC, only hydrogen-bonded dimers are retained in the melt (nematic phase).     

Molecular and crystal structure of <Emphasis Type="Italic">n</Emphasis>-hexyloxybenzoic anhydride at low and room temperatures

The crystal and molecular structures of n-hexyloxybenzoic anhydride, C₆H₁₃-O-C₆H₄-C(O)-O-C(O)-C₆H₄-C₆H₁₃, at low (120 K) and room (296 K) temperatures have been investigated. The molecule has an asymmetric bent structure. The dihedral angle between the benzene ring planes is 48.5°. The aliphatic chain on one side of the molecule has a transoid orientation with respect to the “internal” C4 atom of the closest benzene ring, whereas the aliphatic chain on the other side has a cissoid orientation with respect to the analogous C(4A) atom. The crystal packing does not exhibit any pronounced separation of the crystal space into closely packed aromatic or loosely packed aliphatic regions. No weak directional interactions are observed in the packing; this fact explains the absence of liquid-crystal properties for this compound.     

Ferrocenylbiphenylyl- and ferrocenylterphenylyl-containing liquid crystals: Solid-phase precursors, structure, and properties

This paper reports on the results of investigations into the liquid-crystal properties and structure of compounds belonging to a new class of mesogens containing monosubstituted ferrocenyl fragments, such as 4′-ferrocenyl-1,1′-biphenyl- and (terphenyl)-4-yl 4-alkoxybenzoates of the general formula Fc-(C₆H₄) _m -O₂C-C₆H₄-O-C _n H_2n+1 (m = 2, 3; n = 6, 8, 10, 12) and 4-alkoxyphenyl 4′-ferrocenyl-1,1′-biphenylyl-4-carboxylates of the general formula Fc-(C₆H₄)₂-CO₂-C₆H₄-O-C _n H_2n+1 (n = 10, 12). The crystal packings of the ferrocene-containing mesogens are theoretically predicted and calculated, and the results obtained are discussed.     

Two new CrIII(bpb)(H2O)X complexes derived from [Cr(bpb)(N3)2]− or [Cr(bpb)(CN)2]− (bpb2− = 1,2-bis(pyridine-2-carboxamido)benzenate, X− = hydroxo or azide)

Two new Cr(III) complexes, [Cr(bpb)(H₂O)(OH)]·3H₂O (1) and [Cr(bpb)(H₂O)(N₃)]·H₂O (2) have been synthesized and structurally characterized. Both complexes were unexpectedly obtained as single crystals during the reactions of [Cr(bpb)(CN)₂]⁻ or [Cr(bpb)(N₃)₂]⁻ with [Ni(L)](ClO₄)₂ (L = 3,10-dimethyl-1,3,6,8,10,12-hexaazacyclotetradecane) or MX₂·nH₂O (M = Cu, Ni and Mn, X = Cl⁻ and ClO₄ ⁻). Complex 1 crystallizes in the triclinic system, space group P-1, formula CrC₁₈H₂₁N₄O₇ with a = 7.1543(17) ?, b = 12.420(3) ?, c = 12.955(3) ?, α = 115.021(5)°, β = 95.544(5)°, and γ = 101.575(5)°. Complex 2 crystallizes in the monoclinic system, space group P2₁/c, formula CrC₁₈H₁₆N₇O₄ with a = 11.7171(9) ?, b = 9.4999(7) ?, c = 16.8799(13) ?, and β = 97.449(2)°. Both complexes exhibit distorted octahedral coordination environment with four nitrogen atoms of bpb²⁻ situated at the equatorial plane (Cr–N bond distances range from 1.961(3) to 2.1088(15) ?), and the remaining two trans-positions occupied by terminal ligands H₂O/HO and H₂O/N₃ in 1 and 2, respectively. It is noteworthy that a hydrogen-bonded folded ladder-like structure involving twelve O atoms in 1 and a chair-like hexagonal hydrogen-bonded cluster containing six O atoms are formed.     

Structural determination by X-Ray diffraction and 183W NMR spectroscopy of mono substituted hexatungstates [(n-C4H9)4N]3MW5O19 (M = Nb, V)

The tetrabutylammonium salt of mononiobotungstate [(n-C₄H₉)₄N]₃NbW₅O₁₉ (1) and the tetrabutylammonium salt of monovanadotungstate [(n-C₄H₉)₄N]₃VW₅O₁₉ (2) are isotypes; both crystallize in the monoclinic system, space group C2/c (N° 15) with Z=8. The cell parameters for 1 are a=30.4038(8) ?, b=18.5948(8) ?, c=27.3330(3) ?, β=112.4555(6)°, V=14281.1(7) ?³ and the final reliability factors are R=0.043 and R _w=0.047 for 5801 reflections. The cell parameters for 2 are a=30.096(8) ?, b=18.373(3) ?, c= 27.201(6) ?, β=112.402(14)°, V=13906(5) ?³ and the final reliability factors are R=0.048 and R _w=0.054 for 6122 reflections. Both anions, [NbW₅O_19] ³⁻ and [VW₅O_19] ³⁻ exhibit the Lindqvist structure of the parent hexatungstate anion. The six metal positions are disordered and for each metal site the occupation factor is close to 1/6 M (M=Nb, V) and 5/6 W. Furthermore the two compounds were characterized by IR in the solid state, and ¹⁸³W solution NMR. The ¹⁸³W spectrum of [NbW₅O_19] ³⁻ presents two resonances with relative intensities 4:1 in agreement with the C_4v symmetry of the anion.     

Crystal structure of complexes of bivalent Co,Ni, and Cd with anions of benzoic and 2-(acetylamino)-5-nitrobenzoic acids

The structure of three complexes of bivalent metals (cobalt, nickel, and cadmium) with anions of benzoic (HL ¹) and 2-(acetylamino)-5-nitrobenzoic (HL ²) acids, namely, [Co₂¹ (H₂O)₂(μ-C₄H₄N₂)] _n (I), [NiL²(H₂O)₅]L² · 2H₂O (II), and [Cd(μ-L ²)₂(H₂O)₂] _n · 2nH₂O (III), is determined. In chainlike structure I, cobalt atoms are connected by bridging pyrazine molecules; structure II contains isolated complexes. In structure III, centrosymmetric (CdOCO)₂ cycles and polymeric ribbons are formed due to the coordination of the carboxylate group of the L ² ligand to two cadmium atoms.     

Synthesis,Structure and Reactivity of Electron Deficient Triosmium Cluster Bearing 2,6-Dimethylbenzothiazolide Ligand

Abstract  

Reaction of [Os₃(CO)₁₀(NCMe)₂] with 2,6-dimethylbenzothiazole at room temperature affords [Os₃(CO)₁₀(μ-H){μ-η ²-C₇H₂NS(Me)₂}] (1) in 45% yield. Decarbonylation of 1 in refluxing toluene furnishes the electron-deficient cluster [Os₃(CO)₉(μ-H){μ ₃-η ²-C₇H₂NS(Me)₂}] (2) in almost quantitative yield. Treatment of 2 with PPh₃ at 40 °C gives the addition product [Os₃(CO)₉(PPh₃)(μ-H){μ-η ²-C₇H₂NS(Me)₂}] (3) in 85% in which the PPh₃ ligand is coordinated to the rear osmium atom. A similar treatment of 2 with P(OMe)₃ gives [Os₃(CO)₉{P(OMe)₃}(μ-H){μ-η ²-C₇H₂NS(Me)₂}] (4) in 60% yield with P(OMe)₃ ligand also coordinated to the rear metal. Compounds 3 and 4 differ by the disposition of the hydride ligands. In compound 4 both the hydride and the heterocyclic ligands simultaneously bridge the same metal–metal edge whereas they bridge different metal–metal edges in 3. Compounds 1–4 have been characterized by a combination of elemental analysis, infrared, NMR and mass spectral data together with single crystal X-ray diffraction studies for 3. Compound 3 crystallizes in the monoclinic space group P2₁/n with a = 9.2659(10), b = 23.643(2), c = 16.382(3) Å, β = 91.324(12)°, Z = 4 and V = 3,587.8(8) Å³.     

X-ray diffraction study of p -(alkoxybenzylidene)- p ′-toluidines C2H5O-C6H4-CH=N-C6H4-CH3 and C4H9O-C6H4-CH=N-C6H4-CH3

The molecular and crystal structures of two p-alkoxybenzylidene)-p′-toluidines C₂H₅O-C₆H₄-CH=N-C₆H₄-CH₃ (1) and C₄H₉O-C₆H₄-CH=N-C₆H₄-CH₃ (2) are determined by X-ray diffraction. Crystals 1 and 2 contain four and two crystallographically independent molecules, respectively. In 1, the geometry of the independent molecules is almost identical. In 2, the independent molecules differ in the conformation of the alkyl chain, which is disordered in one of them. An analysis of the crystal packing of 2 reveals the alternation of spacious layers formed by loosely packed aliphatic fragments of molecules and layers of closely packed aromatic fragments, which ensures the formation of the mesogenic phase in the course of melting of crystals 2. In crystal 1, loose aliphatic layers are absent. Original Russian Text ? L.G. Kuz’mina, N.S. Kucherepa, M.N. Rodnikova, 2008, published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 1072–1078.     

X-ray diffraction study of R2[UO2(C3H2O4)2] ·H2O (R = K or Rb)

Compounds K₂[UO₂(C₃H₂O₄)₂] · H₂O (I) and Rb₂[UO₂(C₃H₂O₄)₂] · H₂O (II) are synthesized and their crystal structures are determined by X-ray diffraction. The compounds crystallize in the monoclinic crystal system; for I, a = 7.1700(2) ?, b =12.3061(3) ?, c = 14.3080(4) ?, β = 95.831(2)°, space group P2₁/n, Z = 4, and R = 0.0275; for II, a = 7.1197(2) ?, b = 12.6433(4) ?, c = 14.6729(6) ?, β = 96.353(2)°, space group P2₁/n, Z = 4, and R = 0.0328. It is found that I and II are isostructural. The main structural units of the crystals are the [UO₂(C₃H₂O₄)₂]²⁻ chains, which belong to the AT ¹¹ B ⁰¹ (A = UO₂²⁺, T ¹¹, and B ⁰¹ = C₃H₂O₄²⁻) crystal chemical group of uranyl complexes. The chains and alkali metal ions R (R = K or Rb) are connected by electrostatic interactions and hydrogen bonds. Some specific structural features of [UO₂(C₃H₂O4)₂]²⁻ complex groups are discussed.     

Dielectric Anisotropy and the Order Parameter of HXBBA

Abstract

Measurements of dielectric anisotropy (Δ?), refractive indices (n _e , n _o), birefringence (Δn) and density (ρ) have been made in the nematic and smectic phases of N(-p-hexyloxybenzylidene)-p-butylaniline (HXBBA). The results indicate that the various transitions are of the first order type except smectic B-smectic G, which may be a second order transition. The order parameter S has been determined using the isotropic internal field model (Vuks approach) and the anisotropic internal field model (Neugebauer's approach) and both the values agree fairly well. The dielectric anisotropy (Δ?) increases strongly in the smectic phases whle S increases only slowly. It is interpreted by an increase of dipole-dipole correlations.     

Synthesis and structural analysis of Bis(2-hydroxyphenyl) phenylamine, PhN(o-C6H4OH)2: Comparison with Tris(2-hydroxyphenyl)amine N(o-C6H4OH)3

The molecular structures of N(o-C₆H₄OH)₃, PhN(o-C₆H₄OH)₂, andp-TolN(o-C₆H₄OMe)₂ have been determined by X-ray diffraction, thereby indicating several structural differences. For example, whereas the nitrogen in N(o-C₆H₄OH)₃ is pyramidal with Σ_C–N–C = 348.3^∘, the nitrogen atoms in PhN(o-C₆H₄OH)₂ andp-TolN(o-C₆H₄OMe)₂ are trigonal planar with Σ_C–N–C = 359.9^∘ and Σ_C–N–C = 360.0^∘, respectively. The phenyl andp-tolyl groups of PhN(o-C₆H₄OH)₂ andp-TolN(o-C₆H₄OMe)₂ lie close to the trigonal plane, while theo-C₆H₄OH ando-C₆H₄OMe groups are almost orthogonal to this plane. The coplanar and orthogonal orientations of the aryl groups of PhN(o-C₆H₄OH)₂ andp-TolN(o-C₆H₄OMe)₂ are in marked contrast to those of the phenyl groups within Ph₃N, which exhibit dihedral angles in the range 38–52^∘ and approximateD₃ symmetry. The observed structures of PhN(o-C₆H₄OH)₂ andp-TolN(o-C₆H₄OMe)₂ may be rationalized in terms of maximizing delocalization of the nitrogen lone pair into the phenyl andp-tolyl groups, while minimizing unfavorable overlap with theo-C₆H₄OH ando-C₆H₄OMe groups due to the presence of π-donatingortho-substituents; the orthogonal orientation of theo-C₆H₄OH ando-C₆H₄OMe groups is also one that minimizes unfavorable steric interactions between theortho-substituents.     

Synthesis and Study of New Mesogens II: p-(p′-n-Alkoxycinnamoyloxy)-benzylidene p″ -anisidines (1) and p-(p′-n-Alkoxycinnamoyloxy)- benzylidene anilines (2)

Two new homologous series of liquid crystals viz. p-(p'-n-alkoxycinnamoyloxy) benzylidene p”-anisidines (1) and p-(p'-n-alkoxycinnamoyloxy) benzylidene anilines (2) comprising twenty four mesogens have been synthesized. Both are high melting series of mesomorphs. In the homologous series (1) the nematic mesophase is exhibited from the very first member; however, the first five compounds decompose at high temperatures before passing into isotropic liquid condition. Polymesomorphism is exhibited with the appearance of the smectic mesophase at the octyl derivative and remains up to the last viz. octadecyl homologue. Within polymesomorphic region the nematic mesophase is homeotropic; however, it shows a clear threaded texture where it is the only mesophase shown i. e. in the first seven members of the homologous series (1). The smectic mesophase shows focal conic fan shape texture belonging to smectic-A variety. The nematic-isotropic curve shows descending tendency as the series is ascended-a characteristic of high melting series. The smectic-nematic transition curve rises steeply and shows a levelling off tendency at the octadecyl derivative. In the homologous series (2), no decomposition occurs. The smectic mesophase commences a little early i. e. from hexyl derivative; while polymesomorphism is clearly exhibited up to the dodecyl derivative, the last two homologues are purely smectogens. The usual odd-even effect is observed in case of the nematic-isotropic curve for series (2). The smetic-nematic curve rises gradually and seems to be merging with the falling nematic-isotropic curve at the fifteenth homologue. The mesomorphic ranges in both series are quite wide; however, that of series (1) is wider than one obtained in series (2). Thermal stabilities are good and are in keeping with the molecular characteristics. The textures of the smectic and nematic mesophases are similar to that of the series (1). Both series are comparable with each other and other related series.     

Synthesis,Crystal Structures and Thermal Analysis of Two New Silver(I)–Dithioether Lamellar Coordination Polymers

Abstract  Two new silver(I)–dithioether coordination polymers based on the self-assembly of the dithioether ligands L ^{n −R} = CH₃–S(CH₂) _n S–CH₃ (n = 1, 3) and AgX silver salts, where X = ClO₄ ⁻ (1) and PF₆ ⁻ (2), have been synthesized and characterized by single crystal X-ray diffraction and TGA. The crystallographic data of those complexes are: (1) Monoclinic P2₁/c; a = 16.5861(3) ?; b = 10.1048(2) ?; c = 15.7843(3) ?; β = 112.570(1)°; V = 2442.83(8) ?³; Z = 4. (2) Monoclinic P2₁/n; a = 8.6500(2) ?; b = 9.4053(2) ?; c = 24.0357(6) ?; β = 92.750(2)°; V = 1953.19(8) ?³; Z = 4. In both complexes, the dithioether building blocks propagated the silver(I) centers to build cationic lamellar coordination polymers, while ClO₄ ⁻ and PF₆ ⁻, which were sandwiched between silver-ligand sheets, counterbalance only the charge of the networks. The thermogravimetric investigation reveals that those complexes decompose in a single step respectively to metallic silver and silver salt. Index Abstract  Two new silver(I)–dithioether coordination polymers, obtained from the self-assembly of dithioether ligands and AgX salts with noncoordinating counteranions (X = ClO₄ ⁻ and PF₆ ⁻), were characterized by X-ray crystallography and thermogravimetric analysis (TGA).      

X-ray diffraction study of p -(alkoxybenzylidene)- p ′-toluidines C5H11O-C6H4-CH=N-C6H4-CH3 and C8H17O-C6H4-CH=N-C6H4-CH3

The molecular and crystal structures of two p-(alkoxybenzylidene)-p′-toluidines C₅H₁₁O-C₆H₄-CH=N-C₆H₄-CH₃ (1) and C₈H₁₇O-C₆H₄-CH=N-C₆H₄-CH₃ (2), which form the nematic phase upon melting, is determined by X-ray diffraction. The geometry of the benzylideneaniline fragments in molecules 1 and 2 is actually identical. The crystal packings of 1 and 2 are characterized by the alternation of layers formed by loosely packed aliphatic fragments of molecules and layers of closely packed aromatic fragments. The packing in the aromatic regions of 1 follows the parquet pattern. The crystal packing of 2 has a stacking structure, which is formed by π-stacking dimers superimposed on one another. The formation of the mesogenic phase upon melting of crystals 1 is due to the disturbance of the structurality of loose aliphatic layers with retention of the structure of the aromatic regions, which are stabilized by the cooperative effect of weak directed C-H ··· π-system interactions. The mesogenic phase of crystals 2 is formed upon melting as a consequence of the retention of the structure of π-stacking dimers. Original Russian Text ? L.G. Kuz’mina, N.S. Kucherepa, M.N. Rodnikova, 2008, published in Kristallografiya, 2008, Vol. 53, No. 6, pp. 1079–1085.     

Tetra-n-butylammonium bromide-thiourea (1/2), a layer-type inclusion compound

The inclusion compound built of tetra-n-butylammonium bromide-thiourea (1/2), [(n-C₄H₉)₄N⁺Br^– 2(NH₂)₂CS], has been prepared and characterized by X-ray crystallography. The compound crystalline in orthorhombic space group Pbca, with a = 16.872(6) Å, b = 17.214(6) Å, c = 18.561(6) Å, V = 5390(3) ų, Z = 8. The compound features a sandwich-like crystal structure built up from planar layers. In the crystal structure, zigzag hydrogen-bonded thiourea ribbons are linked by bromide anions to generate puckered layers matching the (100) planes, and the (n-C₄H₉)₄N⁺ cations occupy the intervening space.     

Crystal and molecular structure of Sr2( Edta ) · 5H2O, Sr2(H2 Edta )(HCO3)2 · 4H2O, and Sr2(H2 Edta )Cl2 · 5H2O strontium ethylenediaminetetraacetates

Three Sr²⁺ compounds with the Edta ⁴⁻ and H₂ Edta ²⁻ ligands—Sr₂(Edta) · 5H₂O (I), Sr₂(H₂ Edta)(HCO₃)₂ · 4H₂O (II), and Sr₂(H₂ Edta)Cl₂ · 5H₂O (III)—are synthesized, and their crystal structures are studied. In I, the Sr(1) atom is coordinated by the hexadentate Edta ⁴⁻ ligand following the 2N + 4O pattern and by two O atoms of the neighboring ligands, which affords the formation of zigzag chains. The Sr(2) atom forms bonds with O atoms of five water molecules and attaches itself to a chain via bonds with three O atoms of the Edta ⁴⁻ ligands. The Sr(1)-O and Sr(2)-O bond lengths fall in the ranges 2.520(2)–2.656(3) and 2.527(3)–2.683(2) ?, respectively. The Sr(1)-N bonds are 2.702(3) and 2.743(3) ? long. In II and III, the H₂ Edta ²⁻ anions have a centrosymmetric structure with the trans configuration of the planar ethylenediamine fragment. The N atoms are blocked by acid protons. In II, the environment of the Sr atom is formed by six O atoms of three H₂ Edta ligands, two O atoms of water molecules, and an O atom of the bicarbonate ion, which is disordered over two positions. In III, the environment of the Sr atom includes six O atoms of four H₂ Edta ²⁻ ligands and three O atoms of water molecules. The coordination number of the Sr atoms is equal to 8 + 1. In II and III, the main bonds fall in the ranges 2.534(3)–2.732(2) and 2.482(2)–2.746(3) ?, whereas the ninth bond is elongated to 2.937(3) and 3.055(3) ?, respectively. In II, all the structural elements are linked into wavy layers. The O-H…O interactions contribute to the stabilization of the layer and link neighboring layers. In III, hydrated Sr²⁺ cations and H₂ Edta ^– anions form a three-dimensional [Sr₂(H₂ Edta)(H₂O)₃] _n ²ⁿ⁺ framework. The Cl⁻ anions are fixed in channels of the framework by hydrogen bonds with four water molecules. In II and III, the N-H groups form four-center N-H…O₃ hydrogen bonds, which include one intermolecular and two intramolecular components. PACS numbers: 61.66.Hq Original Russian Text ? I.N. Polyakova, A.L. Poznyak, V.S. Sergienko, 2009, published in Kristallografiya, 2009, Vol. 54, No. 2, pp. 262–267.