(18-Crown-6)potassium tetrachloroferrate(III), dibromodichloroferrate(III), and tetrabromoferrate(III): Synthesis and crystal structures

Three new crystalline complexes are synthesized: [K(18-crown-6)]⁺ · An, where An = [FeCl₄]^?(I), [FeBr₂Cl₂]^? (II), and [FeBr₄]^? (III). The crystals of compounds I–III are cubic and isomorphic, space group Fd $ \bar 3 Three new crystalline complexes are synthesized: [K(18-crown-6)]⁺ · An, where An = [FeCl₄]⁻(I), [FeBr₂Cl₂]⁻ (II), and [FeBr₄]⁻ (III). The crystals of compounds I–III are cubic and isomorphic, space group Fd (Z = 16): a = 20.770(2) ? for I, 20.844(3) ? for II, and 20.878(4) ? for III. Structures I–III are solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.047 (I), 0.059 (II), and 0.098 (III) for all 680 (I), 684 (II), and 686 (III) independent reflections. In two tetrahedral anions [Fe(1)X₄]⁻ and [Fe(2)X₄]⁻ in structures I–III, all halogen atoms (X = Cl and Br) are randomly disordered over three close positions relative to the crystallographic axes 3. Structures I–III contain the [K(18-crown-6)]⁺ host-quest complex cation. The K⁺ cation (CN = 8) resides in the cavity of the 18-crown-6 ligand and coordinated by its six O atoms and two disordered halogen X atoms. The coordination polyhedron of the K⁺ cation in complexes I–III is a distorted hexagonal bipyramid. Original Russian Text ? A.N. Chekhlov, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 9, pp. 1566–1570.     

Thermoanalytical and mass spectrometric study of Ni(iso-Bu2PS2)2 and NiL(iso-Bu2PS2)2 (L = 2,2′-Bipy, Phen). Saturation vapor pressure over the Ni(iso-Bu2PS2)2 chelate

The thermal behaviors of the chelate Ni(iso-Bu₂PS₂)₂ (I) and the mixed-ligand complexes Ni(2,2′-Bipy)(iso-Bu₂PS₂)₂ (II) and Ni(Phen)(iso-Bu₂PS₂)₂ (III) in air are reported. These compounds can pass into the gas phase, as was demonstrated by vacuum sublimation for I and by vacuum distillation for II and III in a gradient furnace. The mass spectra of I–III are presented and discussed. The temperature dependence of the saturation vapor pressure over I and ΔH _T ⁰ and ΔS _T ⁰ and of evaporation of I determined by the vapor transport method are reported.     

Specific Features of Chlorotropism in the ENC Triad (E = PIV-PVI,C) of High-Coordination Phosphorus Chlorides and Trichloromethyl Isocyanate

The semiempirical MNDO method and its parametrized PM3 version in supermolecular approximation was used for a comparative study of the structure and alternative mechanisms of chlorotropism in the ENC triad (E = P^{I V - V I}, C) of amidinium tetrachlorophosphorate Cl₄P(NCH₃)₂CCCl₃ (I), phosphazopentachloroethane Cl₅C₂NPO₂C₆H₄, (II), trichloromethyl isocyanate Cl₃CNCO (III), and their 1:2 chloroform solvates. The absence of the thermodynamically stable intermediate as a separated ion pair in the chlorotropic transformations of structures I, III and the high enthalpy of the substrate-intermediate transformation for structure II show that the sigmatropic mechanism of chlorotropism in compounds under study is the only probable one. The activation barrier of chlorotropism in phosphorus systems I, II is much reduced. In the case of specific solvation, a weak tendency to further reduction of the activation barrier for structures I-III is observed, and the equilibrium for phosphorus systems I, II, is appreciably shifted, unlike system III, where, according to experimental data, the equilibrium is fully to the side of the carbamoyl isomer Cl₂C = NC(O)Cl.     

Structural features and N-H…O and O-H…O hydrogen-bonded supramolecular frameworks in 2-methylanilinium hydrogen DL-malate hydrate, 4-methoxyanilinium and 4-methylanilinium hydrogen DL-malate salts

In the crystal structure of 2-methylanilinium hydrogen DL-malate hydrate (I), an additional water molecule is present in asymmetric unit. In the crystal structures of 4-methoxyanilinium hydrogen DL-malate (II) and 4-methylanilinium hydrogen DL-malate (III), the hydrogen malate anions exhibit configurational disorder with major component occupy S-configuration and minor component occupy R-configuration provided both (II) and (III) are prepared from a racemic mixture of DL-malic acid. In crystal structures of compounds (I)–(III), the hydrogen malate anions and anilinium cations from O-H…O and N-H…O hydrogen bonds which exhibit interesting supramolecular frameworks. In compound (I), the N-H…O and O-H…O hydrogen-bonded anionic-cationic framework form two-dimensional hydrophilic and hydrophobic layers in which the lattice water molecules are embedded in hydrophilic layers. However, in crystal structures of (II) and (III), the hydrogen DL-malate anions form two-dimensional anionic substructure through O-H…O hydrogen bond, in which the anilinium cations are anchored through N-H…O hydrogen bonds.

     

Synthesis and structure of gold and copper complexes: [Ph3PhCH2P]+[AuCl4]?, [NH(C2H4OH)3]+[AuCl4]? · H2O, and [Ph3EtP] 2+ [Cu2Cl6]2?

Triphenylbenzylphosphonium tetrachloroaurate (I) and triethanolammonium tetrachloroaurate hydrate (II) were prepared by reacting tetrachloroauric acid in acetone with triphenylbenzylphosphonium and triethanolammonium, respectively. Triphenylethylphosphonium hexachlorodicuprate (III) was synthesized from triphenylethylphosphonium chloride and copper chloride in acetone. The crystal structures of complexes I to III were determined by single-crystal X-ray diffraction. The phosphorus atoms in complex I have a nearly undistorted tetrahedral coordination (CPC, 108.3°–110.6°; P-C, 1.788–1.793 ?). The coordination of nitrogen atoms in the cations of complex II is a distorted tetrahedron (CNC, 111.7°–112.4°). The square coordination of aurum in I and II is only slightly distorted: the ClAuCl angles are 89.6°–90.3° (I) and 89.5°–90.6° (II) and the Au-Cl distances are 2.256–2.278 ? I) and 2.280–2.285 ? (II). The phosphorus atoms in complex III are tetracoordinated (CPC, 106.34°–111.73°; P-C, 1.790–1.795 ?). The copper atoms in III have a distorted tetrahedral coordination (ClCuCl, 98.48°–144.85°; Cu-Cl, 2.1999–2.3263 ?). The central fragment Cu₂Cl₂ in the anion of complex III is bent relative to the Cu₂ axis (the chlorine atom deviates from the Cu₂Cl plane by 0.27 ?).     

Formation of Cu<Superscript>I</Superscript>(CH<Subscript>3</Subscript>CN)<Subscript>4</Subscript>ClO<Subscript>4</Subscript> in the reactions of copper(II) perchlorate with acetonitrile in the presence of sulfur-containing organic compounds

Cu(ClO₄)₂·6H₂O was shown to react with 2,2′-[propane-1,3-diylbis(thio-2-phenylnemethylidene]-bis(3-pyridylamine) (I) or (5Z)-2-ethoxycarbonylmethyl-(2-pyridylmethylidene)-3,5-dihydro-4H-imidazol-4-one (II) in the presence of CH₃CN with the reduction of copper(II) to copper(I) and the formation of the tetrahedral complex Cu^I(CH₃CN)₄ClO₄ (III). In the course of the reaction the organic ligands I and II were oxidized to the corresponding sulfoxides.     

Synthesis and study of Iron(II) perrhenate complexes with 4-propyl-1,2,4-triazole exhibiting 1A1 ? 5T2 spin transition

Coordination compounds of iron(II) perrhenate with 4-propyl-1,2,4-triazole (L), [Fe₃L₆(ReO₄)₄(H₂O)₂](ReO₄)₂(I), [Fe₃L₆(H₂O)₆](ReO₄)₆·H₂O(II), and FeL₃(ReO₄)₂(III), were synthesized. Compounds I and III were studied by static magnetic susceptibility measurements and by IR and electronic spectroscopy. These complexes exhibit a reversible ¹ A ₁ ⇄ ⁵ T ₂ spin transition and thermochromism. Compound I exhibits a spin transition without hysteresis at 185 K. The temperatures of forward and reverse transition for III are 250 and 244 K, respectively. Complex II isolated by crystallization from an acidified aqueous solution of compound I has a linear trinuclear structure of the cation (X-ray diffraction data). The structure of complex I was assumed to be similar, while compound III has a polymeric structure. Original Russian Text ? M.B. Bushuev, L.G. Lavrenova, Yu.G. Shvedenkov, A.V. Virovets, L.A. Sheludyakova, S.V. Larionov, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 1, pp. 51–56.     

Geometric Isomers of Cobalt(II) and Cobalt(III) Picolinates in Solution

Cobalt complexes with picolinic acid (HPic), namely, [Co^II(Pic)₂(H₂O)₂] · 2H₂O (I) and [Co^III(Pic)₃] · H₂O (II) are studied using ¹H and ¹³C NMR spectroscopy. Compound Iexists in solution as three geometric isomers, namely, trans-trans-trans, cis-trans-cis, and trans-cis-cis(molar ratio 4 : 2 : 1, respectively). According to ¹³C NMR data, compound IIexists in solution as a mer-isomer. The relative energy stability of the isomers was estimated using the molecular mechanics method.     

Bismuth compounds [Ph3BuP]+I?, [Ph3BuP] 2+ [Bi2I8 · 2Me2C=O]2?, and [Ph3BuP] 2+ [Bi2I8 · 2Me2S=O]2?: Syntheses and crystal structures

The complexes [Ph₃BuP]₂⁺[Bi₂I₈ · 2Me₂C=O]²⁻ (II) and [Ph₃BuP]₂⁺[Bi₂I₈ · 2Me₂S=O]²⁻ (III) are synthesized by the reactions of triphenyl(n-butyl)phosphonium iodide (I) with bismuth iodide in acetone and dimethyl sulfoxide. In the cations of complexes I–III, the P atoms have a distorted tetrahedral coordination (CPC angles 106.3(2)°–112.0(3)°). The butyl group in cation I is disordered over two positions. In the binuclear centrosymmetric anions of structures II and III, the octahedrally coordinated bismuth atoms are linked in pairs by two bridging (br) iodine atoms (Bi-I_br 3.1508(7) and 3.2824(8) ? in compound II, 3.1961(3) and 3.3108(3) ? in complex III), which are coplanar to four terminal (t) iodine atoms (Bi-I_t 2.9260(7) and 2.9953(6) ? in complex II, 2.9206(3) and 2.9786(3) ? in complex III). The two remaining positions at the bismuth atom are occupied by the iodine atom (Bi-I_t 2.8531(7) ? in complex II, 2.8984(3) ? in complex III) and O atom of the organic molecule (Bi-O 2.747(6) ? in complex II, 2.507(3) ? in complex III). Original Russian Text ? V.V. Sharutin, I.V. Egorova, N.N. Klepikov, E.A. Boyarkina, O.K. Sharutina, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 3, pp. 188–192.     

Synthesis and properties of the Cu(II) complexes with chiral bis{( E )-[(1 S ,4 R )-Δ7,8-1-amino-2- para -menthalidene]aminohydroxy}methane (L — a derivative of natural terpenoid ( R )-(+)-limonene). Crystal structure of the [Cu(L)(μ-Cl)CuCl3] · iso -PrOH solvate

The Cu₂LCl₄ complex (I) with chiral bis{(E)-[(1S,4R)-Δ^7,8-1-amino-2-para-menthalidene]aminohydroxy} methane (L — a derivative of natural monoterpenoid (R)-(+)-limonene) is synthesized. The crystal structure of the solvate of complex I[Cu(L)(μ-Cl)CuCl₃] · iso-PrOH (II) is determined by X-ray diffraction analysis. Structure II is based on molecules of the [Cu(L)(μ-Cl)CuCl₃] binuclear complexes in which L is the tetradentate cycleforming ligand. One Cl atom manifests the bridging function. The CuN₄ Cl coordination unit is a square pyramid, and CuCl₄ is a distorted tetrahedron. The iso-PrOH molecules are localized in cavities between the layers of structure II. The μ_eff value for complex I is 2.56 μB and indicates the absence of an appreciable interaction between the Cu²⁺ ions in the Cu(II)-Cl-Cu(II) exchange cluster. The compound CuLCl₂· H₂O (III) is synthesized. The μ_eff value for compound III is 1.6 μB. Complexes I and III are studied by EPR and IR spectroscopy. Original Russian Text ? T.E. Kokina, L.A. Glinskaya, R.F. Klevtsova, E.G. Boguslavskii, L.A. Sheludyakova, S.N. Bisyaev, A.V. Tkachev, S.V. Larionov, 2009, published in Koordinatsionnaya Khimiya, 2009, Vol. 35, No. 3, pp. 202–211.     

Binuclear Pd(II) complexes with chiral ethylenediaminodioxime (H2L) and bis-α-thiooxime (H2L1), the derivative of monoterpenoid(+)-3-carene. Crystal structures of [Pd2(H2L)Cl4] and [Pd2(H2L1)Cl4] · 3CDCl3

Diamagnetic Pd(II) complexes with the chiral ethylenediaminodioxime (H 2 L) and bis-α-thiooxime (H₂L¹), the derivatives of monoterpenoid (+)-3-carene, of the composition Pd₂(H₂L)Cl₄(I), Pd₂(H₂L¹)Cl₄ (II), and the solvate Pd₂(H₂L¹)Cl₄·3DCl₃ (III) were synthesized. The crystal structures of complex I and solvate III were determined from X-ray diffraction data. The structures consist of acentric binuclear molecules with the coordination cores PdN₂Cl₂ (in I) and PdNSCl₂ (in III) in the form of the distorted squares. In complex I, each Pd atom coordinates two N atoms of the tetradentate bridge-cyclic ligand H₂L and two Cl atoms; in compound III, one N and one S atom of the tetradentate bridge-cyclic ligand H₂L¹, and 2 Cl atoms. The CDCl₃ molecules in compound III lie in the cavities formed by the molecules of complex II. In both structures, the PdCl₂ fragments are in the trans-positions. The ¹H NMR spectra indicate that the structures of complexes I, II in solutions are similar to the structures of compounds I, III in the solid state. Original Russian Text ? T.E. Kokina, L.I. Myachina, L.A. Glinskaya, A.V. Tkachev, R.F. Klevtsova, L.A. Sheludyakova, S.N. Bizyaev, A.M. Agafontsev, N.B. Gorshkov, S.V. Larionov, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol. 34, No. 2, pp. 120–132.     

Synthesis and photoluminescence of Zinc(II) complexes with tetrafluoroterephthalic acid (H2L). Crystal structure of coordination polymer [Zn(H2O)4(L) · 4H2O]n

Complexes Zn(H₂O)₄(L) (I) and Zn(H₂O)(L) (II) (H₂L = p-HOOCC₆F₄COOH) are synthesized. Single crystals of compound [Zn(H₂O)₄(L) · 4H₂O] _n (III) are grown. According to the X-ray diffraction data, the crystal structure of compound III is built of zigzag chains of coordination polymer Zn(H₂O)₄(L) and molecules of water of crystallization. The chain contains ions Zn²⁺, whose octahedral coordination sphere includes the O atoms of four water molecules and two O atoms of the deprotonated carboxyl groups. The chains in structure III are joined by a system of hydrogen bonds of coordinated water molecules and molecules of water of crystallization. The photoluminescence spectrum of H₂L exhibits the band with λ_max = 368 nm. The spectra of compounds III, I, and II contain bands at 322, 340, and 353 nm, respectively.     

Synthesis and properties of Cu(II) and Pd(ii) complexes with chiral bis-α-sulfanyl oxymes,the derivatives of natural monoterpene, α-pinene

Coordination compounds Cu₂(H₂L¹)Cl₄ (I), Pd₂(H₂L¹)Cl₄ (II), Cu₂(H₂L²)Cl₄ (III), and Pd₂(H₂L²) Cl₄ (IV) with chiral bis-α-sulfanyloximes, the derivatives of the monoterpenoid (−)-α-pinene, were obtained. The complexes I and III are paramagnetic (μ_eff = 2.45 and 2.67 μ_B, respectively), II and IV are diamagnetic. According to IR spectroscopy, in the compounds I–IV the nearest environment of Cu and Pd atoms includes N, S, and Cl atoms. The values of μ_eff and parameters of ESR spectra of the solid phase and solutions of I and III show a binuclear structure of the Cu(II) complexes. Parameters of the ¹H and ¹³C NMR spectra of compounds II and IV indicate the formation of binuclear Pd(II) complexes of C ₂ symmetry and the closure of fivemembered chelate rings PdNSC₂. The PdCl₂ fragments are in transoid position. H₂L¹ and H₂L² are tetradentate bridging chelating ligands.     

Structure and properties of double complex salts [Co(NH3)6][Fe(CN)6] and [Co(NH3)6]2[Cu(C2O4)2]3

Double complex salts (DCSs) [Co(NH₃)₆][Fe(CN)₆] (I) and [Co(NH₃)₆]₂[Cu(C₂O₄)₂]₃ (II) and complex [Co(NH₃)₆]₂(C₂O₄)₃·4H₂O (III) are synthesized and investigated by single crystal XRD, crystal optics, and elemental analysis. The crystalline phases of I, II, and III (R-3, P2₁/c, and Pnnm space groups respectively) have the following crystallographic characteristics: a = 10.9804(2) ?, b = 10.9804(2) ?, c = 10.8224(3) ?, V = 1130.03(4) ?³, Z = 3, d _x = 1.65 g/cm³ (I); a = 9.6370(2) ?, b = 10.2452(2) ?, c = 13.2108(3) ?, V = 1932.90(9) ?³, Z = 2, d _x= 1.97 g/cm³ (II), and a = 11.7658(3) ?, b = 11.7254(3) ?, c = 14.1913(4) ?, V = 1304.34(5) ?³, Z = 2, d _x = 1.68 g/cm³ (III). This paper investigates the products of DCS thermolysis in a hydrogen atmosphere: the intermetallic compound CoFe with the bcc parameter a = 2.852 ? for I and a heterogeneous mixture of Co and Cu in the decomposition of II. The coordinated CN⁻ and C₂O₄²⁻ groups then turn into NH₃, hydrocarbons, and CO₂. The dominant hydrocarbon is methane.     

High-temperature spin transition in the iron(II) trifluoromethylsulfonate,perrhenate, and tetraphenylborate complexes with tris(pyrazol-1-yl)methane

New coordination compounds of iron(II) trifluoromethylsulfonate, perrhenate, and tetraphenylborate with tris(pyrazol-1-yl)methane (HC(Pz)₃) of the composition [Fe(HC(Pz)₃)₂]A₂ (A = CF₃SO₃ ⁻ (I), ReO₄ ⁻ (II), and B(C₆H₅)₄ ⁻ (III)) were synthesized and studied by the method of static magnetic susceptibility and IR and electronic spectroscopies. The crystal and molecular structures of compounds I and II were determined by X-ray diffraction analysis. The magnetochemical study of complexes I—III in the interval from 275 to 500 K showed that they possessed the high-temperature spin transition ¹ A ₁ ⇄ ⁵ T ₂ accompanied by thermochromism.     

Synthesis and structure of bismuth complexes [Ph4P]4[Bi8I28], [Ph4P]2[Bi2I8·2Me2S=O]·2Me2S=O, [(Me2S=O)8Bi][Bi2I9]

Complexes [Ph₄P]₂[Bi₂I₈(Me₂S=O)₂]·2Me₂S=O (I) and [Ph₄P]₄[Bi₈I₂₈] (II) were obtained by the reaction of tetraphenylphosphonium iodide with bismuth triiodide in DMSO and acetone, respectively. Dissolving bismith iodide in DMSO resulted in the formation of complex [(Me₂S=O)₈Bi][Bi₂I₉] (III). Reactions of complexes II or III with tetraphenylphosphonium iodide in DMSO yielded complex I. The structure of the obtained bismuth complexes was confirmed by X-ray diffraction data.     

Schwingungsspektren und Kraftkonstanten von Hexamethyldisilan,Hexaphenyldisilan und 1,1,1-Trimethyl-2,2,2-triphenyldisilan

The Raman and infrared spectra of (CH₃)₃SiSi(CH₃)₃ (I), (CD₃)₃SiSi(CD₃)₃, (C₆H₅)₃SiSi(C₆H₅)₃ (II), (CH₃)₃SiSi(C₆H₅)₃ (III), and (CD₃)₃SiSi(C₆H₅)₃ are reported. Assignments are based on symmetry G ₃₆ ⁺ (free internal rotation) forI, D_3d forII, and C_3v forIII. Normal coordinate treatment has been done using some simplifications in the phenyl coordinates. The SiSi stretching force constant inI amounts to 1,65 N/cm. In compoundsII andIII strong vibrational coupling is elucidated byPED calculations.     

Synthesis, structures, and electrophysical properties of single crystals of solid solutions CdGeAs2:Mn(x) and Cd0.964Zn0.036GeAs2:Mn(x)

Single crystals of the solid solutions CdGeAs₂:Mn(x) and Cd_0.964Zn_0.036GeAs₂:Mn(x) have been grown by the vertical Bridgman method. An X-ray diffraction study has demonstrated that Cd_0.964Zn_0.036GeAs₂ (I), Cd_0.964Zn_0.036GeAs₂:Mn (1.5 wt%) (II), and Cd_0.964Zn_0.036GeAs₂:Mn (2.18 wt %) (III) retain the CdGeAs₂ structure (tetragonal system, space group I 2d). The unit cell parameters of the solid solutions are as follows: a = b = 5.934(1) ?, c = 11.219(2) ? for I; a = b = 5.919(1) ?, c = 11.204(2) ? for II; and a = b = 5.918(1) ?, c = 11.208(2) ? for III. Many of Mn atoms in II and III occupy interstitial sites in the crystal lattice. Selected electrical and magnetic properties of single crystals of CdGeAs₂:Mn(x) are discussed. Original Russian Text ? S.G. Mikhailov, K.K. Palkina, A.V. Molchanov, S.F. Marenkin, T.V. Filippova, L.I. Ochertyanova, I.S. Zakharov, A.V. Kochura, R. Laiho, E. Lahderanta, A. Lashkul, M.A. Shakhov, 2007, published in Zhurnal Neorganicheskoi Khimii, 2007, Vol. 52, No. 11, pp. 1879–1885.     

CdS formation upon decomposition of Cd(n-BuOCS2)2 in EtOH and DMF and the crystal structure of Cd(Ph3P)(n-BuOCS2)2 · Ph3P

The thermal decomposition of the chelate Cd(n-BuOCS₂)₂ (I) in EtOH and DMF, either in the absence or in the presence of Ph₃P, yields finely disperse CdS particles. Mixed-ligand complex Cd(Ph₃P)(n-BuOCS₂)₂ (II) has been synthesized. Cd(Ph₃P)(n-BuOCS₂)₂ · Ph₃P (III) single crystals have been grown. By X-ray crystallography, the crystal structure of III is built of [Cd(Ph₃P)(n-BuOCS₂)₂] mononuclear complex molecules and uncoordinated Ph₃P molecules, which reside inside channels formed by complex II molecules. The coordination polyhedron around a Cd atom is a tetragonal pyramid where the base is formed by the four S atoms of the two bidentate chelating ligands n-BuOCS₂⁻ and the P atom of the Ph₃P ligand is at the axial vertex. In the structure of III, there are supramolecular assemblies of two complex II molecules.     

Crystal and molecular structure of 4(3-acryloyloxy)octyloxy- and 4(3-acryloyloxy)hexyloxy-4′-cyanobiphenyls

The molecular and crystal structures of N≡C-C₆H₄-C₆H₄-O-(CH₂)₈-O-CO-CH=CH₂ (4(3-acryloyloxy)octyloxy-4′-cyanobiphenyl) (I) and N≡C-C₆H₄-C₆H₄-O-(CH₂)₆-O-CO-CH=CH₂ (4(3-acryloyloxy)hexyloxy-4′-cyanobiphenyl) (II) were determined by X-ray diffraction. The structures of I and II are stereotype. The space group of I and II is C2/c, Z = 8; lattice parameters I: a = 34.677(7)?, b = 9.452(2)?, c = 13.004(3) ?, β = 99.30(3)°; II: a = 30.858(6) ?, b = 9.504(2) ?, c = 13.082(2) ?, β = 92.78(3)°. The planar extended molecules I and II are packed in the unit cell to give clearly differentiated aliphatic and aromatic regions throughout the whole crystal. All intermolecular contacts are concentrated in the aromatic region. The molecular packing is very loose but the aromatic areas of I and II fully coincide. The only free parameter of the structure is the length of the aliphatic chain (CH₂)n (n = 8 and 6). According to DSC data, compound I possesses enantiotropic mesomorphism and II possesses monotropic mesomorphism.