Two clathrates of bis(isothiocyanato)tetrakis(4-methylpyridine)magnesium(II) as a host with 4-methylpyridine as a guest

Two clathrate modifications of the title host with 4-methylpyridine (4-CH₃C₅H₄N) as a guest have been determined at –50°C. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · 2/3(4-CH₃C₅H₄N) · 1/3H₂O is trigonal, space group , witha=27.630(7),c=11.219(3) ÅV=7417(4) ų,Z=9,D _calc=1.171 g cm^–3,(CuK )=18.506 cm^–1, finalR=0.064. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · (4-CH₃C₅H₄N) is tetragonal, space group I4_l/a, witha=16.944(7),c=23.552(9)Å,V=6762(5) Å,Z=8,D _calc=1.191 g cm^–3, (CuK )=18.200 cm^–1, finalR=0.071.The structures consist of molecular packings of the same host complex units and the guest species. The Mg(II) cation is octahedrally coordinated to theN-atoms of four 4-methylpyridine and twotrans-coordinated isothiocyanato ligands in the host molecule. The conformations of the molecule are considerably different both in symmetry and in geometry in these two structures. The guest 4-methylpyridine molecules are disordered into channels which have different topology in these two clathrates resulting in different thermal stability.     

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     

Clathrate inclusiom compounds of bis(isothiocyanato) tetrakis (4-methylpyridine) nickel II: II. Arrangement of guest molecules in the β-Ni(NCS)2(4-methylpyrldine)4 porous crystals

In this paper crystal structures of three tetragonal 14₁/a β-Ni(NCS)₂(4-Methylpyridine)₄ clathrates containing p-xylene (1:1), m-xylene (1:1) and methanol (2:1 mole of guest/mole of host), respectively, as the guest components are reported and discussed.The guest molecules were found to occupy centrosymmetric cavities in the hoat structure. Non-centrosymmetric m-xylene molecules are disordered to at least two orientations interrelated by inversion; methanol molecules enter the cavities as centrosymmetric pairs.     

Studies in werner clathrates. Part 2. Structures of bis (isothiocyanato) tetra (4-phenylpyridine) nickel (II)· 4-dimethylsulphoxide,bis (isothiocyanato) tetra (3-methylpyridine) nickel (II)· chloroform and bis (isothiocyanato) tetra (3,5-dimethylpyridine) nickel (II)

The structures of Ni(NCS)₂(4-PhPy)₄·4DMSO and Ni(NCS)₂(3-MePy)₄·CHCl₃ have been elucidated. Movement of guest molecules through channels in the host structure was simulated by potential energy calculations. Ni(NCS)₂(3,5-diMePy)₄ does not form inclusion compounds. An intra-molecular potential energy study shows that theortho-hydrogens on the 3,5-dimethylpyridine ligands control the conformation of the molecule. The same result is obtained with the 4-methylpyridine ligand, which suggests that the extent of rotation of substituted pyridines about the Ni–N bounds is not a factor governing clathrate formation. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82030 (43 pages).     

Studies on werner clathrates. Part 131. Selective criteria in werner clathrates. Six crystal structures with bis(isothiocyanato)tetra(4-vinylpyridine)nickel(II) as host

This paper addresses the general question: what are the significant guest properties selected by this host when interacting with guest molecules in the liquid phase, resulting in cocrystallization of the host and guest? In particular, to what extent do π electrons in a guest molecule effect its potential as a guest? Werner clathrates of the host [Ni(NCS)₂(4-ViPy)₄] with mixtures of tetrahydrofuran (THF) and cyclic hydrocarbons as guests have been synthesised and their structures elucidated. Clathrate (1): [Ni(NCS)₂(4-ViPy)₄](1.78 THF)(0.22 cyclohexane), crystallizes in the orthorhombic space groupP _bcn a=9.976(6),b=20.630(25),c=19.861 (4) Å,V=4087ų,Z=4,R=0.087 for 1461 reflections; (2): [Ni(NCS)₂(4-ViPy)₄](1.76 THF)(0.24 cyclohexene),P _bcn ,a=9.987(7),b=20.614(4),c=19.898(4)Å,V=4096ų,Z=4,R=0.084 for 1304 reflections; (3): [Ni(NCS)₂(4-ViPy)₄](0.48 THF)(0.52 1,3-cyclohexadiene), tetragonalI4₁/a,a=16.898(3),b=16.898(3),c=26.463(6)Å,V=7556ų,Z=8,R=0.120 for 1698 reflections; (4): [Ni(NCS)₂(4-ViPy)₄](0.36 THF)(1.04 1,4-cyclohexadiene),I4₁/a,a=16.986(4),b=16.986(4),c=25.896(15)Å,V=7472ų,Z=8,R=0.103 for 2025 reflections; (5): [Ni(NCS)₂(4-ViPy)₄](0.35 THF)(1.05 benzene),I4₁/a,a=17.102(10),b=17.102(10),c=25.498(8)Å,V=7458ų,Z=8,R=0.118 for 2200 reflections; (6): [Ni(NCS)₂(4-ViPy)₄](3 benzene), triclinicP1,a=10.432(24),b=11.155(9),c=21.581(7)Å, α=78.70(5), β=82.60(7), γ=74.09(13)°,V=2361ų,Z=2,R=0.078 for 3427 reflections. Host-guest ratios and, for mixtures of guests, guest1/guest2 ratios, were elucidated by density and NMR. We show that the conformational freedom of the substituted pyridines is not the primary reason for the clathrating ability of Werner hosts. All six structures show no host-guest interaction at the level of van der Waals interactions. As non-bonding interactions are not observed between the host and guest, this study shows that the above host's selectivity by enclathration of particular guest molecules cannot be accounted for by solid state structural analysis.     

Competition among aromatic guests for the host tetrakis(4-methylpyridine)nickel(II) isothiocyanate and a basis for the observed selectivity

In continuing attempts to determine the basis for the selectivity shown by the host Ni(4-mepy)₄(NCS)₂ (1) toward aromatic guests, distribution data between solid and liquid phases are reported for seven ternary systems at room temperature. These consist of1,p-xylene, and each of the following:p-bromotoluene,p-chlorotoluene,p-fluorotoluene,p-dichlorobenzene, benzene, and 4-methylpyridine, as well as the system1-p-chlorotoluene-p-dichlorobenzene. The results, as well as those for five systems already published, have been reviewed and a hierarchy of selectivity developed. After correcting the observed selectivity for inequality of guest vapour pressures the order of decreasing preference is found to bep-bromotoluene >p-dichlorobenzene >p-chlorotoluene > deuterated and protiatedp-xylenes > ethylbenzene > 4-methylpyridine >p-fluorotoluene > toluene > benzene. With the exception of 4-methylpyridine, this is the same as the order of decreasing van der Waals length of the guest molecule and, where known, the order of enthalpy of inclusion. Although longer guest molecules and those with higher vapour pressures are favoured in selectivity, guests with longer molecules are likely to have lower vapour pressures. The activity coefficients of the included guests are calculated assuming that the liquid phases follow Raoult's law.Portions of this paper were presented at the Second and Fourth International Symposia on Clathrate Compounds and Molecular Inclusion Phenomena held in Parma, Italy, 1982 and Lancaster, England, 1986.     

Crystal structures of inclusion compounds of 4-aminobenzenesulfamidine (sulfaguanidine) with two dicyclohexano-18-crown-6 isomers

The crystal structures of inclusion compounds of 4-aminobenzenesulfamidine (sulfaguanidine) (L) with two dicyclohexano-18-crown-6 (DCH-6) isomers A(cis-syn-cis) and B(cis-anti-cis) have been determined by X-ray methods. The complexes exhibit 1:2 host-guest ratios. In fact the complex of isomer A is formulated as [DCH-6^A·[L]H₂O]L (complexI), while that of isomerB is DCH-6 ^B L₂ (complex I1).In the crystals, host and guests are connected by O-H...0 and N-H...O bonds.     

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.     

Synthesis and Crystal Structure of Tetrakis（4—methylpyridine）bis（μ4—pentathio）—tetracopper（Ⅰ）（4—methylpyridine）solvate

1 INTRODUCTION An interesting aspect in the studies of copper-sulfur coordination chemistry is the apparent tendency of Cu(Ⅰ) ions to form various clusters with sulfur ligands. The coordination chemistry of Cu(Ⅰ) has been studied extensively owing to the importance of Cu(Ⅰ) in biological systems and copper-sulfur bonds detected in some metallopro- teins[1]. More recently, remarkably rich photoluminescence properties have been found in the tetranuclear complexes[2～5] and the cage-ty…     

A thermokinetic study of the clathration of isomeric xylenes by the Ni(NCS)2 (4-methylpyridine)4 host

A detailed analysis of the thermokinetic course of the reaction -Ni(NCS)₂(4-methylpyridine)₄+xylen-e»-Ni(NCS)₂ (4-methylpyridine)₄·(xylene) (at 25 °C), for 21 samples of purep-xylene andm-xylene, as well as two-and three-component mixtures of theo-,m-andp-isomers was performed by using the dynamic optimization method. The mechanism of the reaction is discussed. Firstly, a relatively rapid »-phase transformation and uptake of 60–80% of the total guest takes place. Then follows the slower diffusion-controlled absorption of xylene up to the maximum filling corresponding to 1:1 guest/host stoichiometry.     

Crystal structure analysis of the carbon tetrabromide clathrate of hexakis(phenylseleno)benzene

The 12 inclusion compound of hexakis(phenylseleno)benzene (1) with CBr₄ is trigonal, space groupR , witha=14.474(3),c=21.487(4) Å, and three host and six guest molecules in a unit cell referred to hexagonal axes. A true clathrate structure is found and in each closed cage there are two carbon tetrabromide guest molecules, orientated such that a C–Br bond of each is colinear with thec-axis of the crystal. Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82002. To obtain copies, see page ii of this issue.     

Synthesis,characterization and antimicrobial activity of pentagonal-bipyramidal isothiocyanato Co(II) and Ni(II) complexes with 2,6-diacetylpyridine bis(trimethylammoniumacetohydrazone)

Pentagonal-bipyramidal isothiocyanato Co(II) and Ni(II) complexes with condensation product of 2,6-diacetylpyridine and trimethylammoniumacetohydrazide (Girard’s T reagent) were synthesized and characterized by elemental analyses, IR and UV–vis spectra, molar conductivity, and magnetic susceptibility. Crystal structures of the Co(II) and Ni(II) complexes were also determined. Antimicrobial activities of the ligand and metal complexes were examined.     

Inclusion complexes of the natural product gossypol. Crystal structures of gossypol complexes with benzene and chloroform as guests

The crystal structures of the lattice inclusion complexes of gossypol with benzene and chloroform have been determined by X-ray structure analysis. The crystals of (C₃₀H₃₀O₈)₂ · C₆H₆ (GPBNZ) are triclinic, space groupPI,a = 11.241(3),b = 14.986(4),c = 17.380(4) Å, = 98.89(2), = 99.86(2), = 98.91(2)°,V = 2800(2) ų,Z = 2,D _x = 1.32 g cm^–3, (CuK ) = 7.35 cm^–1. The structure has been refined to a finalR value of 0.050 for 6146 observed reflections. The crystals of C₃₀H₃₀O₈·CHCl₃ (GPCLF) are monoclinic, space groupC2/c,a = 28.464(4),b = 8.948(1),c = 26.480(4) Å, = 108.93(2)°,V = 6380(2) ų,Z = 8,D _x = 1.33 g cm^–3, (CuK) = 30.42 cm^–1. The structure has been refined to a finalR value of 0.100 for 1980 observed reflections.GPCLF forms an intercalate-type structure and GPBNZ a clathrate-type structure. There are, however, some similarities in the packing mode of the host molecules in these two structures. On a basis of comparison of the crystal packing of GPCLF and GPBNZ one can postulate that in the desorption process of the intercalate-type GPCLF complex an intermediate clathrate structure of the GPBNZ-type should be formed.     

Crystal structure, magnetism and spectroscopy of bis(tetraphenylphosphonium)tetrakis(dicyanamido)cobaltate(II) with bridging and pendant dicyanamide ligands

The synthesis, structure and magnetic properties of the cobalt(II) complex, (Ph₄P)₂[Co(NCNCN)₄] (1) is reported. The compound crystallises in the monoclinic system, space group C2/c, with cell constants: β=105.65(2)°, Z=4 and The structure of 1 consists of octahedral CoN₆ chromophores with uni- and bidentate N(CN)₂ ligands. Cobalt atoms are doubly bridged by bidentate NCNCN groups forming infinite ribbons along the crystallographic b-axis. As first representative of an anionic dicyanamide complex 1 behaves as a weak ferromagnet at low temperatures.     

Synthesis and Crystal Structure of Bis(nitrate)bis(N-n-octyl-α-pyrrolidone)uranyl (II)

1 INTRODUCTION Tri-butyl phosphate (TBP) has been widely used for the extraction reagent in Th-U fuel to separate uranium from thorium. However di-butyl phosphate (DBP) and butyl phosphate (MBP), the radiolytic products of TBP, exhibit some coordinated ability to the fission elements, such as Zr and Nb. The physical and chemical properties of amides and caprolactam are similar to those of TBP, and they selectively extract U(VI) and Th(VI). The principal advantages of amides an…     

Crystal structure of supramolecular complexes formed by 18-crown-6 andcis-anti-cis-dicyclohexano-18-crown-6 (host) with 3,4-diaminofurazane (guest)

An X-ray—diffraction study is reported for two molecular complexes containing 3,4-diamino-1,2,5-oxadiazole as guest (G) with 18-crown-6 (18-C-6) andcis-anti-cis-dicyclohexano-18-crown-6 (DCH-6B) as host. Both complexes are of the polymeric-chain structure with the guest molecule bridging two crown neighbours. ComplexI: [18-C-6*G*H₂O], 111, monoclinic,P2₁/n,a=8.171(1),b=15.042(2),c=16.209(6) Å, =101.15(2)°, finalR-factor 0.068. ComplexII: [DCH-6B*G], 11, monoclinicC2/c,a=21.212(4),b=9.380(2),c=13.049(3) Å, =108.61(3)°, finalR 0.047.     

On the clathrate structures of syndiotactic poly(m-methylstyrene)

The crystal structures of clathrate forms of syndiotactic poly(m-methylstyrene) containing guest molecules having different steric hindrance (CS₂, benzene and orto-dichlorobenzene) are presented. The structures are all characterized by polymer chains in s (2/1)2 helical conformation and guest molecules packed in an orthorhombic unit cell according to the space group Pcaa. All the presented clathrates belongs to β class indipendently from the dimensions of the guest molecule. In this aspect they differ both from clathrate forms of syndiotactic polystyrene, all belonging to α class, and from clathrate forms of syndiotactic poly(p-methylstyrene) that belong to α or β class according to the steric hindrance of the guest molecule.     

Synthesis, structures and spectroelectrochemistry of methyl-substituted bis(η-indenyl)iron(II) complexes

Several new methyl-substituted indenyl ferrocenes were prepared by metathesis reactions of the indenide (generated from the appropriate indene with BuLi) with ferrous chloride. The indenides used to prepare new ferrocenes were: 2-methyl-, 1,2-dimethyl-, 4,7-dimethyl-, 1,4,7-trimethyl-, and 1,3,4,7-tetramethyl-indenide. These indenyl ferrocenes, along with those prepared from indenide, 1-methylindenide, and 1,3-dimethylindenide, were then characterized by ¹H and ¹³C NMR, UV/visible spectroscopy, cyclic voltammetry and mass spectrometry. The cyclic voltammetry showed an additive relationship between oxidation potential and the number of methyl groups which is also position-dependent, whereas the UV/visible spectra showed two absorptions essentially unaffected by methyl substitution. Additionally, bis(2-methylindenyl)iron(II) and bis(4,7-dimethylindenyl)iron(II) were characterized by X-ray crystallography.