Studies in Werner clathrates. Part 4. Structures of tetrakis(4-ethylpyridine)di-isothiocyanatonickel(II) and its clathrates with p-, m-, and o-xylene, carbon disulphide, and carbon tetrachloride

Moore, M. H.; Nassimbeni, Luigi R.; Niven, Margaret L.

doi:10.1039/dt9870002125

Cited by 23 publications

(22 citation statements)

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“…Viable alternative methods include crystallization, absorption, sieving, complexation, isomerization, and a number of hybrid strategies that involve solid-liquid separation. [13] In some cases the host arrangement is preserved after guest removal and the sorption-desorption processes can be cycled by means of solid-vapor reactions. For example, Mitsubishi Gas-Chemical Company isolates mx by means of complexation with tetrafluoroboric acid (HBF 4 ).…”

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confidence: 99%

“…The guestincluded forms can exhibit a variety of structural arrangements; cage-, layer-, and channel-inclusion compounds (referred to as b, g, and d phases, respectively) are all possible, depending on the geometric relationship between the host and the guest. [13] In some cases the host arrangement is preserved after guest removal and the sorption-desorption processes can be cycled by means of solid-vapor reactions. [14] Herein we 1) report new solution-state and solid-vapor preparations of the xylene clathrates of [Ni(NCS) 2 (ppp) 4 ] (1) [15] (ppp = para-phenylpyridine); 2) describe the previously unknown structure of [Ni(NCS) 2 (ppp) 4 ]·3 p-xylene (1 px); 3) demonstrate significant selectivity of 1 for ox over mx and px from a ternary mixture, and then similar selectivity for mx over px from a binary mixture; and 4) identify the reason of such selectivity.The pure octahedral metal complex 1 (Scheme 1) was precipitated by slow evaporation of a methanolic solution as previously reported.…”

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confidence: 99%

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Solid–Vapor Sorption of Xylenes: Prioritized Selectivity as a Means of Separating All Three Isomers Using a Single Substrate

2012

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Solid–Vapor Sorption of Xylenes: Prioritized Selectivity as a Means of Separating All Three Isomers Using a Single Substrate

2012

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“…Therefore, the majority of studies report solvent‐mediated enclathration processes12 while solid–vapor inclusion reactions have received little attention in this particular context. The guest‐included forms can exhibit a variety of structural arrangements; cage‐, layer‐, and channel‐inclusion compounds (referred to as β, γ, and δ phases, respectively) are all possible, depending on the geometric relationship between the host and the guest 13. In some cases the host arrangement is preserved after guest removal and the sorption–desorption processes can be cycled by means of solid–vapor reactions 14.…”

Section: Methodsmentioning

confidence: 99%

Solid–Vapor Sorption of Xylenes: Prioritized Selectivity as a Means of Separating All Three Isomers Using a Single Substrate

Lusi

Barbour

2012

Angewandte Chemie

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Xylenes occur in the three isomeric forms (ortho, meta, and para), hereafter referred to as ox, mx and px, respectively. Together with ethylbenzene, they constitute the so-called C8 aromatic compounds derived from crude oil that serve as starting materials for the synthesis of many important chemical intermediates. These include terephthalic acid, phthalic anhydrides, phthalonitriles, and styrene, which are used in the production of polymers, plastics, resins, pigments, and fungicides. Moreover, xylenes are often added to motor fuel as an anti-knocking agent. [1] Owing to their similar physical properties (boiling points of 144.5, 139.1, and 138.2 8C for ox, mx, and px, respectively), separation of the three isomers is an expensive and inefficient undertaking. Distillation with a view to producing commercial-grade reagents requires more than 150 theoretical plates to isolate the higher-boiling ox and up to 360 plates to further separate mx and px. Viable alternative methods include crystallization, absorption, sieving, complexation, isomerization, and a number of hybrid strategies that involve solid-liquid separation. Some of these processes involve the use of highly reactive chemicals. For example, Mitsubishi Gas-Chemical Company isolates mx by means of complexation with tetrafluoroboric acid (HBF 4 ). More recently, methods that exploit zeolites to separate the para isomer from a vapor mixture have been explored but, owing to low efficiency, they have not yet been implemented on an industrial scale. [2] Indeed, in this type of application the amount of xylene adsorbed (and separated) in each cycle could be relatively small in comparison to the adsorbent (1 % by weight) [3] and the use of a desorbent is often necessary. [4] Related methods that employ metal-organic frameworks have been reviewed by Zhou et al. [5] and attempts to engineer hydrogen-bonded assemblies for the selective inclusion of xylenes have also been reported. [6] A summary of the main industrial separation methods currently used is given in the Supporting Information.More than fifty years ago, a method for the separation of xylenes from the liquid phase was suggested that involves enclathration by octahedral metal complexes with the general formula [ML 4 X 2 ] (where M is a transition metal, X is an anion, and L is a pyridine derivative). [7] These so-called Werner clathrates were not deemed sufficiently viable for industrial applications but they were implemented for chromatographic separation. [8] Indeed, crystallization from solution involves a costly recovery process and also leads to the formation of byproducts that reduce selectivity. [9] Subsequent studies showed that Werner complexes could also effect isotopic [10] and enantiomeric [11] separations when applied to other compounds. From a solid-state structural perspective these host systems are interesting because of the often profound structural differences between their apohost and guest-included forms, thus necessitating significant phase transformations to enclathrate the guest mol...

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“…7 Lipkowski's group also studied clathrate formation in terms of kinetics and thermodynamic stability for Ni(4-MePy) 4 (NCS) 2 . 8 The term "Werner clathrate" was coined by Nassimbeni and co-workers in the 1980s, [9][10][11][12] who explored the versatility of [Ni(NCS) 2 (4-MePy) 4 ] complexes through substitution of the pyridine ligands and/or counterions and their clathrates with xylenes and other guests. 13,14 The porous (open) phases of the Werner clathrates are typically crystallised by forming a Werner complex in the presence of guest molecules or through exposure of an as-synthesised non-porous (closed) Werner complex to solid-liquid and/or solid-vapour reactions with guests.…”

Section: Introductionmentioning

confidence: 99%

Reversible single-crystal to single-crystal phase transformation between a new Werner clathrate and its apohost

et al. 2021

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Studies in Werner clathrates. Part 4. Structures of tetrakis(4-ethylpyridine)di-isothiocyanatonickel(II) and its clathrates with p-, m-, and o-xylene, carbon disulphide, and carbon tetrachloride

Abstract: Studies in Werner Clathrates. Part 4.' Structures of Tetrakis(4-ethy1pyridine)diisothiocyanatonickel(i1) and its Clathrates with p-, m-, and o-Xylene, Carbon Disulphide, and Carbon Tetrachloride t

Cited by 23 publications

References 6 publications

Solid–Vapor Sorption of Xylenes: Prioritized Selectivity as a Means of Separating All Three Isomers Using a Single Substrate

Solid–Vapor Sorption of Xylenes: Prioritized Selectivity as a Means of Separating All Three Isomers Using a Single Substrate

Solid–Vapor Sorption of Xylenes: Prioritized Selectivity as a Means of Separating All Three Isomers Using a Single Substrate

Reversible single-crystal to single-crystal phase transformation between a new Werner clathrate and its apohost

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