Thermodynamic Dissociation Constants for [MPy4(NO3)2]*2Py Clathrates (M=Mn,Co, Ni,Cu)

Abstract

Stoichiometry and thermodynamic parameters of the title clathrates dissociation have been studied with thermoanalytical and strain method techniques. The [MPy₄(NO₃)₂]^*2Py (M = Mn, Co, Ni) clathrates dissociate with collapsing clathrate porous phase and destruction of the host complex to give the respective tripyridine complexes and gaseous pyridine. The [CuPy₄(NO₃)₂]^*2Py dissociates with collapsing clathrate phase but giving the host [CuPy₄(NO₃)₂] complex as individual phase, with the tripyridine complex forming in further course of decomposition. The comparison of the thermodynamic dissociation parameters for the [MPy₄(NO₃)₂]^*2Py series with M = Mn, Co, Ni, Cu, Zn and Cd shows that the differences in the stability of the compounds do not correlate with structural parameters of the clathrates but depend on the nature of the metal cation in the host complex. Thermodynamic stability of these clathrate phases follows the general sequence of stabilty for complexes of the 3d transition metals known as Irwing-Williams sequence: Mn<Fe<Co<Ni<Cu>Zn. These results disclose the main issue of instability of the [MPy₄(NO₃)₂]^*2Py clathrates as instability of the respective host complexes.     

Structure reinterpretation and determination of the clathrate nature of the compounds of the general formula MX2·6Py

Unit cell parameters and space group (Ccca) were determined by X-ray diffraction analysis for 11 compounds of the general formula [MPy₄X₂]·2Py (M=Cd, Co, Cu, Ni, Zn; X=Br, I, NO₃, HCOO). It was found that these compounds, together with the five known compounds, form a large group of clathrates, in which [MPy₄X₂) (host) complex molecules are packed with pyridine (guest) molecules held in the voids of the crystal framework by van der Waals forces. The results of the study and literature data are analyzed, and it is concluded that there are at least several dozens more clathrates of the molecular formula MX₂·6Py that are known but not defined structurally. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Physical Chemistry, Polish Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 6, pp. 1070–1073, November–December 1995. Translated by L. Smolina     

Thermodynamic Stability of the [M(Pyridine) 4 X 2 ] * 2G Clathrates as a Function of the Host Components (M, X) and Included Guest (G)

This study compares thermodynamic stability of clathrate compounds belonging to three isomorphous series: [Mpy₄(NCO)₂]^*2Py (M = M(II) = Mn, Fe, Co, Ni), [Mpy₄(NO₃)₂]^*2Py (M = Mn, Co, Ni, Cu, Zn), and [CuPy₄(NO₃)₂]^*2G (G = pyridine, benzene, THF, chloroform). Thermodynamic parameters (Δ H_av ⁰, Δ S_av ⁰ and Δ G₂₉₈ ⁰ of the dissociation of the clathrates were determined from the dependences of the guest equilibrium pressure over the clathrates versus temperature (tensimetric method). Clathrate phases, when differed only in the host formula, demonstrated the same order of thermodynamic stability as one expected for the host complexes in solution: Mn < Fe < Co < Ni < Cu > Zn for M and NCO > NO₃ for X. The influence of the host complex formulation was comparable to the effect of guest template, the effect observed in the third series with the variation of the guest component. This study illustrates a dramatic impact of the stability of the host molecule on the overall stability of the clathrate phases, the impact being comparable to a contribution arising from the host–guest complementarity.     

CONTACT STABILIZATION OF HOST COMPLEX MOLECULES DURING CLATHRATE FORMATION: THE PYRIDINE-ZINC NITRATE AND THE PYRIDINE-CADMIUM NITRATE SYSTEMS

Abstract

Clathrate formation ranges of the phase diagrams of two binary systems Py-Zn(NO₃)₂ and Py-Cd(NO₃)₂ (Py = pyridine) were studied. A clathrate of composition [MPy₄(NO₃)₂]·2Py (M = Zn, Cd) was observed in each of the systems. The space group Ccca (orthorhombic system) and the parameters of the unit cells of both clathrates were determined by X-ray analysis of their single crystals. The data obtained show them to be isostructural with the clathrate [NiPy₄(NO₃)₂]·2Py whose structure is known and suggest the actual presence of the host molecules trans-[MPy₄(NO₃)₂] (M = Zn,Cd) inside the clathrate phases. Host complexes do not form as separate compounds but can only arise in clathrate phases due to contact stabilization by the guest molecules. Both Zn- and Cd-clathrates are of constant composition and melt incongruently at 62.3(6) and 106.0(5)°C, respectively, yielding the complexes [ZnPy₃(NO₃)₂] and [CdPy₃(NO₃)₂], these melting congruently at 131.4(5) and 169.5(5)°C, respectively. During thermal decomposition under quasi-equilibrium conditions with different pressures of the liberating pyridine both clathrates also decompose in one stage, giving [MPy₃(NO₃)₂] complexes. The results obtained are discussed in relation to a number of other systems with Schaeffer's and Hofmann-lwamoto's clathrates in which contact stabilization occurs or might be expected to occur.     

Crystal structure of the dinitratotetrakis(pyridine)nickel(II) clathrate with pyridine as guest, [NiPy4(NO3)2]·2Py

The structure of the [NiPy₄(NO₃)₂]·2Py clathrate was determined by single crystal X-ray diffraction analysis (KM-4 diffractometer, λMoK_a radiation, graphite monochromator, ω/2θ scan mode, θ_max=30°, 640 reflections, R=0.065). Orthorthombic base-centered unit cell, space group Ccca, a=12.148(5), b=15.019(4), c=16.96(1) Å, Z=4C₃₀H₃₀N₈NiO₆, d_calc=1.411 g/cm³. The structure is of island type and consists of distorted octahedral trans-[NiPy₄(NO₃)₂] (host) and pyridine (guest) molecules. The Ni(II) cation coordinated by four nitrogens of the pyridine ligands and two oxygens of the nitrato groups lies in the special position 222; the twofold axes coincide with the directions of the metal-ligand bonds. The guest pyridine molecules lie on the twofold axes that are parallel to the c axes and are oriented in such a way that the total dipole moment of the guest subsystem is zero.     

Crystal structure of the bis(isothiocyanato)tetrakis(pyridine)nickel(II) clathrate with a pyridine guest [NiPy4(NCS)2]·2Py

The structure of the [NiPy₄(NCS)₂]·2Py clathrate was determined by single crystal X-ray diffraction analysis (Enraf-Nonius CAD4 diffractometer, λCuK_α radiation, Ni filter, ω/2θ scan mode, θ_max, 511 reflections, R=0.046). The crystals are tetragonal, space group 14₁/acd, a=16.079(2), c=27.150(7) Å, Z=8 C₃₂H₃₀N₈NiS₂, d_calc=1.229 g/cm³. The structure is of the island type and consists of distorted octahedral trans-[NiPy₄(NCS)₂] (host) and pyridine (guest) molecules. The Ni(II) cation is coordinated by six nitrogen atoms and occupies the 222 special position. One of the twofold axes passes axially through the nickel(II) cation and the atoms of the isothiocyanate groups, and the two other axes lie in the equatorial plane of the Ni(N_Py)₄ complex as diagonals between the Ni−N_Py bonds. The Ni−N_CS and Ni−N_Py distances are 2.033(7) and 2.121(4) Å, respectively. The rings of the pyridine ligands form angles of 53.2(2)° with the equatorial plane of the complex. The guest pyridine molecules lie inside the winding channels running along the c axis. Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Physical Chemistry, Polish Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 6, pp. 1074–1082, November–December, 1995. Translated by L. Smolina     

Crystal Structure of Nickel- and Cobalt-Diazidotetrapyridinemetal(II)-2(Pyridine) Clathrates

[MPy₄(N₃)₂]2Py (M = Ni, Co) are clathrates where two of six pyridine species are included in the crystal structure of the host complex without chemical bonding. The clathrates are isostructural, orthorhombic, space group Pnna (52), Z = 4. For the Ni compound a = 14.958(5), b = 11.909(5), c = 17.517(7) Ú, V = 3120(2) Ú₃, µ = 12.25 cm-¹, final R = 0.057.The Cocompound is of very similar structure (a = 14.980(3), b =11.980(2), c = 17.350(5) Ú, V = 3114(1) Ú³, µ = 46.50 cm-¹. The metal cation in the host molecule is surrounded by six donor nitrogens of two terminal azido-groups in trans-positions and four pyridine ligands. The complex molecule lies on a twofold axis parallel to a.     

Crystal structure of a 1∶2∶1 packing complex formed by bis(isothiocyanato) tetrakis(pyridine) nickel(II), triphenylmethane,and metanol

The structure of the [NiPy₄(NCS)₂]·2(C₆H₅)₃CH·CH₃OH (Py is pyridine) packing complex was determined by single crystal X-ray diffraction analysis (KM-4 diffractometer, λMoK_α, graphite monochromator, ω/2? scan mode, θ_max, 2073 reflections, R=0.059). The unit cell is base-centered monoclinic, space group C2/c, a=20.22(1), b=14.256(7), c=18.836(6) Å, β=87.40(4)^°, Z=4C₆₁H₅₆N₆NiOS₂, d_calc=1.239 g/cm³. The structure is of the island type and consists of molecules of three types. In the trans-[NiPy₄(NCS)₂] molecule, the central atom has a distorted octahedral environment and is coordinated by six nitrogen atoms of two isothiocyanate and four pyridine ligands. In contrast to the phase of the complex itself, this molecule acquires a four-lobe propeller conformation, in which the pyridine rings are rotated relative to the equatorial plane by angles of 52.8(3) and 50.1(2)^°. The triphenylmethane molecule has a three-lobe propeller conformation, as in triphenylmethane clathrates with benzene, thiophene, pyrrole, and aniline, but strongly deviates from threefold axis symmetry. The phenyl rings form dihedral angles of 25(3), 40(4), and 19(4)^° with the planes formed by the bonds of the ternary carbon atoms with hydrogen atoms and by the appropriate carbon atom of the phenyl ring. The methanol molecules are located inside the direct channels running along the c axis and are disordered around the inversion centers.     

On the Search of Metallated Sulfonamides: Synthesis and X‐ray Characterization of the New Sulfathiazolato Nickel(II)‐Chelate Complex [Ni(STZ)2(Py)2]·2Py (STZ = Sulfathiazolato Anion; Sulfathiazole = N1‐2‐thiazolyl‐sulfanilamide; Py = Pyridine)

Sulfathiazole (HSTZ) reacts with triethylamine and Ni(CH₃COO)₂·4H₂O in methanol and further with pyridine to give the sulfathiazolato complex [Ni(STZ)₂(Py)₂]·2Py. In the new chelate complex the deprotonated sulfonamidic nitrogen atom does not take part in the coordination process, apparently retaining the negative charge. Two (STZ)^? moieties are symmetrically bonded to the Ni²⁺ ion through a thiazolyl nitrogen atom and an oxygen atom of the S(O)₂ group. Two pyridine molecules accomplish the fairly distorted octahedral coordination at the metal centre.     

One‐dimensional Diamagnetic‐metal Nitronyl Nitroxide Radical Complexes with Dicyanoargentate(I) Bridges: M(NIT4Py)2[Ag(CN)2]2 (M= Zn,Cd)

Two diamagnetic‐metal nitronyl nitroxide radical complexes with dicyanoargentate(I) bridges M(NIT4Py)₂[Ag(CN)₂]₂ (M= Zn, Cd) were synthesized. X‐ray crystallography reveals that the two compounds are isomorphous, which crystallize in the triclinic space group. Their structures consist of infinite chains of M(NIT4Py)₂ units linked by [Ag(CN)₂]^? μ₂‐bridging ligands. The magnetic measurements showed that the χ_MT values are nearly constants at higher temperature for both complexes. The sharp decreasing of χ_MT values at lower temperature are related to intermolecular antiferromagnetic interactions, which result from the shortest interchain contacts of nitroxide groups in the crystals.     

Processes of Thermal Dissociation of Clathrates on the Base of Coordination Compounds

Inclusion compounds are very interesting materials for thermoanalytical investigations. Stable guest molecules are packed in the cages, channels or layers in the host matrix, thermal dissociation reactions are reversible and have the clear-cut stoichiometry. The clathrates with a matrix of coordination compounds (of the type [MA₄X₂]·nA) were synthesized (M=transition metals; A=Py, 4-MePy; X=NO₃, NCS, NCO; n=0.67 or 1 or 2). Four Py or MePy molecules are tightly bound in the coordination sphere by M-N bonds and others are confined in the matrix cavities by van der Waals forces. Processes of thermal dissociation of the clathrates were studied. Q-thermogravimetry (for checking the stable intermediate phases) and the home-made gas-flow reactor (as EGA-device for kinetic studies) were used. The compensation dependence (lgA_i=aE_i+b) was observed for the most of clathrates series, it was explained by the identity of the reaction mechanism. This revised version was published online in August 2006 with corrections to the Cover Date.     

Pyridinium‐Chlorometallate von Lanthanoid‐Elementen. Die Kristallstrukturen von [HPy]2[LnCl5(Py)] mit Ln = Eu,Er, Yb und von [H(Py)2][YbCl4(Py)2] · Py

Pyridinium Chlorometallates of Lanthanoid Elements. Crystal Structures of [HPy]₂[LnCl₅(Py)] mit Ln = Eu, Er, Yb und von [H(Py)₂][YbCl₄(Py)₂] · Py The pyridinium chlorometallates [HPy]₂[LnCl₅(Py)] with Ln = Eu, Er and Yb, as well as [H(Py)₂][YbCl₄(Py)₂]·Py have been obtained by the reaction of diacetone alcohol with solutions of the corresponding metal trichlorides in pyridine at 100 °C. According to the crystal structure determinations the anions [LnCl₅(Py)]^2— are linked by bifurcated Cl···H···Cl bridges with the protons of the [HPy]⁺ cations forming chains along [001]. The anions of [H(Py)₂][YbCl₄(Py)₂]·Py form discrete octahedrons with trans‐positions of the pyridine ligands. [HPy]₂[EuCl₅(Py)] ( 1a ): Space group Pnma, Z = 4, lattice dimensions at —80 °C: a = 1874.4(2), b = 1490.2(2), c = 741.5(1) pm, R₁ = 0.0466. [HPy]₂[ErCl₅(Py)] ( 1b ): Space group Pnma, Z = 4, lattice dimensions at —80 °C: a = 1864.3(1), b = 1480.7(2), c = 739.7(1) pm, R₁ = 0.0314. [HPy]₂[YbCl₅(Py)] ( 1c ): Space group Pnma, Z = 4, lattice dimensions at —80 °C: a = 1858.9(2), b = 1479.0(1), c = 736.8(1) pm, R₁ = 0.0306. [H(Py)₂][YbCl₄(Py)₂]·Py ( 2 ·Py): Space group Ia, Z = 4, lattice dimensions at —80 °C: a = 1865.5(1), b = 827.5(1), c = 1873.4(1) pm, ß = 103.97(1)°, R₁ = 0.0258.     

Effects of Coordinating Solvents on the Supramolecular Assembling of Tectons arised from the Metallation of Sulfamethoxazole: Synthesis and Structural Characterization of Polymeric [Cd(sulfamethoxazolato)2(L)2]n {L = N,N‐dimethylformamide (DMF); Dimethyl Sulfoxide (DMSO)} and [Cd(sulfamethoxazolato)2(Py)2]n·n(Py)(Py =pyridine)

Cadmium acetate reacts with sulfamethoxazole (5‐methyl‐3‐isoxazolyl sulfanilamide) and with DMF / DMSO / pyridine to give the crystalline polymers [Cd(sulfamethoxazolato)₂(L₂)]_n {L = DMF ( 1 ), DMSO ( 2 )} and [Cd(sulfamethoxazolato)₂(Py)₂]_n·n(Py) ( 3 ). Complexes 1 , 2 and 3 confirm the tectonic character of the [Cd(sulfamethoxazolato)₂(L)₂] moieties and the remarkable ability of the {Cd(sulfamethoxazolato)₄} fragments to be non selectively stabilized by monodentate ligands. In the polymeric assemblies of the title complexes the cadmium(II) atoms are linked through sulfamethoxazolato anions which alternate in their coordination with the isoxazolic N‐atoms and the aromatic amino groups. The chains of vicinal rings build tunnels along the crystallographic c axis.     

Syntheses,Crystal Structures and Non‐linear Optical Properties of Cluster Compounds [MoAu2S4(PPh2Py)2] and [WAu2S4(PPh2Py)2]

The cluster compounds, [MoAu₂S₄(PPh₂Py)₂] ( 1 ) and [WAu₂S₄(PPh₂Py)₂] ( 2 ), were synthesized by the reaction of (NH₄)₂MS₄ (M = Mo, W), H[AuCl₄]·4H₂O and diphenyl‐2‐pyridyl‐phosphine (PPh₂Py) in CH₂Cl₂ solution. [MoAu₂S₄(PPh₂Py)₂] crystallizes in the monoclinic space group P2₁/c with a = 18.385(2), b =12.304(1), c = 16.904(2) Å, β =110.722(2)°, and Z = 4. [WAu₂S₄(PPh₂Py)₂] crystallizes in the triclinic space group P‐1 with a = 9.333 (3), b = 10.628(3), c = 19.566(6) Å, α = 89.26(1), β = 80.87(1), γ = 68.85(1)°, and Z = 2. Single crystal X‐ray analysis showed that these two compounds are isostructural, but belong to different space groups. The Mo (W) atom has a slightly distorted tetrahedral coordination, and the two Au atoms are distorted from trigonal planar, the P—Au—M—Au—P chain is nearly linear. Measurement of the nonlinear optical (NLO) properties using the Z‐scan technique with an 8‐ns pulsed laser at 532 nm showed that 1 and 2 possess NLO absorption and effective self‐focusing effect. The effective α₂ and n₂ values of cluster 1 are 5.89 × 10^—12 m · W^—1 and 6.45 × 10^—18 m² · W^—1; the effective α₂ and n₂ values of compound 2 are 4.35 × 10^—11 m · W^—1 and 3.73 × 10^—17 m² · W^—1.     

Crystal Structure and Thermodynamic Stability of the [Hg(Pyridine)4(NO3)2] · 2(Pyridine) Inclusion Compound

The studied compound belongs to the family of [MPy₄X ₂] . 2Py isomorphous clathrates. Its crystal structure exhibits a van der Waals architecture formed by neutral [HgPy₄(NO₃)₂] host molecules, with the guest pyridine molecules included in the cavities of the host lattice. The host complex is formed by coordination of four pyridines, located near the equatorial plane, and two nitrates, located axially, to the Hg(II) cation. One of nitrates ligates as a monodentate ligand and another as a bidentate. The coordination polyhedron is HgN₄O₃, with average Hg—N_Py and Hg—O_nitrate distances of 2.38(5) and 2.68(1) Å, respectively. The crystal structure is complicated with a superlattice and the crystal symmetry reduced to monoclinic, as compared to the structure usually occurring in the [MPy₄X₂] . 2Py clathrates. The pyridine vapor pressure over the clathrate was measured in the 293--369 K temperature range by the static tensimetric method. Thermodynamic parameters of the clathrate dissociation were calculated from these data. For the reaction 1/3[HgPy₄(NO₃)₂] . 2Py_solid=1/3[HgPy₃(NO₃)₂] _solid + Py_gas the parameters are as follows: H⁰_av = 49.4(2) kJ/mol, S ⁰_av = 127(2) J/(mol K) and G⁰₂₉₈=11.4(3) kJ/mol. The results are compared with previously reported data on compounds of the [MPy₄(NO₃)₂] . 2Py series.     

Synthesis, characterization, electrochemical studies, and antibacterial activities of cobalt(III) complexes with Salpn-Tipe Schiff base ligands. Crystal structure of trans-[CoIII(L1)(Py)2]ClO4

The synthesis, characterization, spectroscopic and electrochemical properties of trans-[Co^III(L¹)(Py)₂]ClO₄ (I) and trans-[Co^III(L²)(Py)₂]ClO₄ (II) complexes, where H₂L¹ = N,N′-bis(5-chloro-2-hydroxybenzylidene)-1,3-propylenediamine and H₂L² = N,N′-bis(5-bromo-2-hydroxybenzylidene)-1,3-propylenediamine, have been investigated. Both complexes have been characterized by elemental analysis, FT-IR, UV-Vis, and ¹H NMR spectroscopy. The crystal structure of I has been determined by X-ray diffraction. The coordination geometry around cobalt(III) ion is best described as a distorted octahedron. The electrochemical studies of these complexes revealed that the first reduction process corresponding to Co(III/II) is electrochemically irreversible accompanied by dissociation of the axial Co-N(Py) bonds. The in vitro antimicrobial activity of the Schiff bse ligands and their corrsponding complexes have been tested against human pathogenic bacterias such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, and Escherichia coli. The cobalt(III) complexes showed lower antimicrobial activity than the free Schiff base ligands.     

Synthesis and Structure of Co(III) Coordination Compounds [Co(DH)2(Anil)2][BF4] and [Co(DH)2(Py)2][BF4]

The complex compounds [Co(DH)₂(Anil)₂][BF₄] and [Co(DH)₂(Py)₂][BF₄] were synthesized from Co(BF₄)₂ · 6H₂O–DH₂–A–alcohol–water systems (DH₂ is dimethylglyoxim and A is pyridine (Py) or aniline (Anil)), and their crystal structures were determined using X-ray diffraction analysis. In octahedral Co(III) complexes, two dimethylglyoxime radicals lie in the equatorial plane and are joined via the intramolecular hydrogen bond O–H···O. The complexes with pyridine and aniline have similar configurations but different crystal structures.     

Darstellung der Halogeno-Pyridin-Rhenate(III), [ReX6−n (Py)n](3−n)− (X = Br,Cl; n = 1−3), sowie Kristallstrukturen von trans-[(C4H9)4N][ReBr4(Py)2], mer-[ReCl3(Py)3] und mer-[ReBr3(Py)3]

Preparation of Halogeno Pyridine Rhenates(III), [ReX_6?n(Py)_n]^(3?n)? (X = Br, Cl; n = 1?3) Crystal Structures of trans-[(C₄H₉)₄N][ReBr₄(Py)₂], mer-[ReCl₃(Py)₃], and mer- [ReBr₃(Py)₃] The mixed halogeno-pyridine-rhenates(III), [ReX_6?n(Py)_n]^(3?n)? (X = Br, Cl), n = 1?3, have been prepared for the first time by reaction of the tetrabutylammoniumsalts (TBA)₂[ReX₆] (X = Br, Cl) in pyridine with (TBA)BH₄ and separation by chromatography on Al₂O₃. Apart from the monopyridine complexes only the trans and mer isomers are formed from the bis-and tris-pyridine compounds. The X-ray structure determinations of the isotypic neutral complexes mer- [ReX₃(Py)₃] (monoclinic, space group P 2₁/n, Z = 4; for X = Cl: a = 9,1120(8), b = 12,5156(14), c = 15,6100(13) Å, β = 91,385(7)°; for X = Br: a = 9,152(5), b = 12,852(13), c = 15,669(2) Å, β = 90,43(2)°) reveal, due to the stronger trans influence of pyridine compared with Cl and Br, that the Re? X distances in asymmetric Py? Re? X3 axes with ReCl3 = 2,397 Å and ReBr3 = 2,534 Å are elongated by 1,3 and 1% in comparison with symmetric X1? Re? X2 axes with ReCl1 = ReCl2 = 2,367 Å and ReBr1 = 2,513 and ReBr2 = 2,506 Å, respectively. The Re? N bond lengths are roughly equal with 2,12 Å. Trans-(TBA)[ReBr₄(Py)₂] crystallizes triclinic, space group P1 , a = 9,2048(12), b = 12,0792(11), c = 15,525(2) Å, α = 95,239(10), β = 94,193(11), γ = 106,153(9)°, Z = 2. The unit cell contains two independent but very similar complex anions with approximate D_2h(mmm) point symmetry.     

Clathrate forming ability of some [MgA4X2] complexes where A=4-methylpyridine or pyridine and X=halogen or NCS

Three new compounds have been synthesized: [Mg(4-MePy)₄(NCS)₂]·0.67(4-MePy)·xH₂O (x=0.07–0.24 [Mg(4-MePy)₄(NCS)₂]·(4-MePy) and [MgPy₄(NCS)₂]·2Py·2H₂O. Their structures have been investigated by Raman spectroscopy and the first two compounds have been shown to be isostructural with the clathrates [Cu(4-MePy)₄(NCS)₂]·0.67(4-MePy)·0.33H₂O and [Ni(4-MePy)₄(NCS)₂]·(4-MePy). Thermal and other properties have been studied. It was concluded from an analysis of the literature that pyridine complexes of Mg and Ca are capable of forming clathrates with Py as guest molecule, although these compounds have not been examined before from the point of view of clathrate chemistry.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated from Zhurnal Strukturnoi Khimii, Vol. 34, No. 2, pp. 66–73, March–April, 1993.     

X-ray diffraction study of a clathrate with the quinoline-containing werner complex ([NiQ 4(NCS)2]·2Q)

The structure of a clathrate with the quinoline-containing Werner complex as a host was determined by single-crystal X-ray diffraction analysis. The crystals of [NiQ ₄(NCS)₂] ·2Q, C₅₆H₄₂N₈S₂Ni are orthorhombic, space group Pca2₁,a = 15.194(9),b = 12.840(7),c = 24.74(1) å, Z = 4, d_calc = 1.307 g/cm³. The final R = 0.063 for 1505 reflections with I > 2Σ(I) and 228 refined parameters; the parameter of the absolute structure is 0.17(7). The structure consists of complex and quinoline guest molecules; the interactions between the molecules are van der Waals interactions. In the host molecule, Ni(II) is surrounded by a distorted octahedron of six nitrogen atoms of two isothiocyanate groups in the trans-position and four quinoline ligands. The molecule has a propeller conformation; the phenylene rings of the quinoline ligands lie on the same side of the equatorial plane. The host molecule is chiral, as the structure on the whole. The quinoline guest molecules lie in the layers that are perpendicular to the z axis. In its general features, the compound is similar to clathrates of [MA₄X₂] type complexes, where A is pyridine and its derivatives.