1,3,5-Tri(iodoethynyl)-2,4,6-trifluorobenzene: halogen-bonded frameworks and NMR spectroscopic analysis

2017 ◽  
Vol 73 (2) ◽  
pp. 153-162 ◽  
Author(s):  
Patrick M. J. Szell ◽  
Bulat Gabidullin ◽  
David L. Bryce
Keyword(s):  
Solid State ◽  
Crystal Engineering ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Lewis Base ◽  
Phosphonium Salts ◽  
Covalent Interaction ◽  
Framework Materials ◽  
Engineering Strategy ◽  
Triphenylphosphonium Bromide

Halogen bonding is the non-covalent interaction between the region of positive electrostatic potential associated with a covalently bonded halogen atom, named the σ-hole, and a Lewis base. Single-crystal X-ray diffraction structures are reported for a series of seven halogen-bonded cocrystals featuring 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene (1) as the halogen-bond donor, and bromide ions (as ammonium or phosphonium salts) as the halogen-bond acceptors: (1)·MePh3PBr, (1)·EtPh3PBr, (1)·acetonyl-Ph3PBr, (1)·Ph4PBr, (1)·[bis(4-fluorophenyl)methyl]triphenylphosphonium bromide, and two new polymorphs of (1)·Et3BuNBr. The cocrystals all feature moderately strong iodine–bromide halogen bonds. The crystal structure of pure [bis(4-fluorophenyl)methyl]triphenylphosphonium bromide is also reported. The results of a crystal engineering strategy of varying the size of the counter-cation are explored, and the features of the resulting framework materials are discussed. Given the potential utility of (1) in future crystal engineering applications, detailed NMR analyses (in solution and in the solid state) of this halogen-bond donor are also presented. In solution, complex13C and19F multiplets are explained by considering the delicate interplay between variousJcouplings and subtle isotope shifts. In the solid state, the formation of (1)·Et3BuNBr is shown through significant13C chemical shift changes relative to pure solid 1,3,5-tris(iodoethynyl)-2,4,6-trifluorobenzene.

scholarly journals Catalytic Activation via π –Backbonding in Halogen Bonds?

2020 ◽  
Author(s):  
Andrew Wang ◽  
Pierre Kennepohl
Keyword(s):  
Halogen Bond ◽  
Halogen Bonding ◽  
Lewis Base ◽  
Computational Studies ◽  
Halogen Bonds ◽  
Covalent Interaction ◽  
Lewis Bases ◽  
Chemical Catalysis ◽  
Catalytic Activation

The role of halogen bonding (XB) in chemical catalysis has largely involved using XB donors as Lewis acid activators to modulate the reactivity of partner Lewis bases. We explore a more uncommon scenario, where a Lewis base modulates reactivity via a spectator halogen bond interaction. Our computational studies reveal that spectator halogen bonds may play an important role in modulating the rate of S<sub>N</sub>2 reactions. Most notably, π acceptors such as PF<sub>3</sub> significantly decrease the barrier to subsitution by decreasing electron density in the very electron rich transition state. Such π-backbonding represents an example of a heretofor unexplored situation in halogen bonding: the combination of both s-donation and π-backdonation in this “non-covalent” interaction.

scholarly journals Catalytic Activation via π –Backbonding in Halogen Bonds?

2020 ◽  
Author(s):  
Andrew Wang ◽  
Pierre Kennepohl
Keyword(s):  
Halogen Bond ◽  
Halogen Bonding ◽  
Lewis Base ◽  
Computational Studies ◽  
Halogen Bonds ◽  
Covalent Interaction ◽  
Lewis Bases ◽  
Chemical Catalysis ◽  
Catalytic Activation

The role of halogen bonding (XB) in chemical catalysis has largely involved using XB donors as Lewis acid activators to modulate the reactivity of partner Lewis bases. We explore a more uncommon scenario, where a Lewis base modulates reactivity via a spectator halogen bond interaction. Our computational studies reveal that spectator halogen bonds may play an important role in modulating the rate of S<sub>N</sub>2 reactions. Most notably, π acceptors such as PF<sub>3</sub> significantly decrease the barrier to subsitution by decreasing electron density in the very electron rich transition state. Such π-backbonding represents an example of a heretofor unexplored situation in halogen bonding: the combination of both s-donation and π-backdonation in this “non-covalent” interaction.

scholarly journals Halogen bonding, chalcogen bonding, pnictogen bonding, tetrel bonding: origins, current status and discussion

2017 ◽  
Vol 203 ◽  
pp. 485-507 ◽  
Author(s):  
Lee Brammer
Keyword(s):  
Solid State ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Main Group ◽  
Solution Phase ◽  
Current Status ◽  
Solid State Chemistry ◽  
Main Group Elements ◽  
Past Work

The role of the closing lecture in a Faraday Discussion is to summarise the contributions made to the Discussion over the course of the meeting and in so doing capture the main themes that have arisen. This article is based upon my Closing Remarks Lecture at the 203rdFaraday Discussion meeting on Halogen Bonding in Supramolecular and Solid State Chemistry, held in Ottawa, Canada, on 10–12thJuly, 2017. The Discussion included papers on fundamentals and applications of halogen bonding in the solid state and solution phase. Analogous interactions involving main group elements outside group 17 were also examined. In the closing lecture and in this article these contributions have been grouped into the four themes: (a) fundamentals, (b) beyond the halogen bond, (c) characterisation, and (d) applications. The lecture and paper also include a short reflection on past work that has a bearing on the Discussion.

Halogen bonding two-point recognition with terphenyl derivatives

2018 ◽  
Vol 42 (13) ◽  
pp. 10476-10480 ◽  
Author(s):  
J. Stoesser ◽  
G. Rojas ◽  
D. Bulfield ◽  
P. I. Hidalgo ◽  
J. Pasán ◽  
...  
Keyword(s):  
Solid State ◽  
Halogen Bond ◽  
Halogen Bonding

Neutral terphenyl-based halogen bond donors form two-point halogen bonding motifs with oxadiazoles in the solid state.

Diaryliodonium as a double σ-hole donor: the dichotomy of thiocyanate halogen bonding provides divergent solid state arylation by diaryliodonium cations

2020 ◽  
Vol 7 (16) ◽  
pp. 2230-2242 ◽  
Author(s):  
Natalia S. Soldatova ◽  
Pavel S. Postnikov ◽  
Vitalii V. Suslonov ◽  
Troyana Yu. Kissler ◽  
Daniil M. Ivanov ◽  
...  
Keyword(s):  
Solid State ◽  
Halogen Bond ◽  
Halogen Bonding

The reactivity of [Ar1Ar2I](SCN) toward the solid-state arylation depends on the preorganization of halogen bond (XB)-bound SCN−: N-XB-bound thiocyanates, which, in contrast to N,S-XB-bound, undergoes the extremely rare N-arylation of SCN−.

Recent Advances in Halogen Bond-assisted Organic Synthesis

2020 ◽  
Vol 24 (18) ◽  
pp. 2118-2152
Author(s):  
Shigeyuki Yamada ◽  
Tsutomu Konno
Keyword(s):  
Organic Synthesis ◽  
Crystal Engineering ◽  
Electron Pair ◽  
Molecular Design ◽  
Halogen Bond ◽  
Covalent Bond ◽  
Lewis Base ◽  
Organic Transformations ◽  
Hydrogen Bond Interaction ◽  
Significant Attention

Halogen bond interactions, which take place between an electrophilic halogen and the electron-pair of a Lewis base and exhibit high directionality (approximately 180°), are non-covalent bond interactions similar to the hydrogen bond interaction. Many reports on halogen bond interactions have been published thus far, but many of them discuss halogen bond in the context of crystal engineering of supramolecular architecture. Since a seminal report by Bolm in 2008, halogen bond-assisted or -promoted organic synthesis has received significant attention. This review aims to introduce the molecular design of suitable halogen bond donors and organic transformations involving halogen bond interactions to afford a variety of organic compounds.

Multifrequency Multiresonance EPR Investigation of Halogen-bonded Complexes Involving Neutral Nitroxide Radicals

2017 ◽  
Vol 231 (4) ◽  
Author(s):  
Thomas Lohmiller ◽  
Mahesh A. Vibhute ◽  
Wolfgang Lubitz ◽  
Anton Savitsky
Keyword(s):  
Halogen Bond ◽  
Liquid Solution ◽  
Lewis Base ◽  
Nitroxide Radicals ◽  
Covalent Interaction ◽  
Pulse Epr ◽  
Epr Parameters ◽  
Frozen Solutions ◽  
Stable Nitroxide ◽  
Bonded Complexes

AbstractHalogen-bonded complexes with neutral nitroxide radicals as the Lewis base have been investigated in liquid and frozen solutions by multifrequency CW and pulse EPR spectroscopies, including ENDOR and ELDOR-detected NMR (EDNMR) techniques. The non-covalent interaction with iodopentafluorobenzene as halogen-bond donor is shown to affect a variety of EPR parameters of the stable nitroxide radicals. In liquid solution, only bulk effects on the EPR signal, i.e. isotropic

scholarly journals Azobenzene-based difunctional halogen-bond donor: towards the engineering of photoresponsive co-crystals

2013 ◽  
Vol 70 (1) ◽  
pp. 149-156 ◽  
Author(s):  
Marco Saccone ◽  
Giancarlo Terraneo ◽  
Tullio Pilati ◽  
Gabriella Cavallo ◽  
Arri Priimagi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
X Ray Diffraction ◽  
Donor Molecule ◽  
X Ray ◽  
Covalent Interaction ◽  
Material Systems ◽  
Azo Group ◽  
Insight Into

Halogen bonding is emerging as a powerful non-covalent interaction in the context of supramolecular photoresponsive materials design, particularly due to its high directionality. In order to obtain further insight into the solid-state features of halogen-bonded photoactive molecules, three halogen-bonded co-crystals containing an azobenzene-based difunctional halogen-bond donor molecule, (E)-bis(4-iodo-2,3,5,6-tetrafluorophenyl)diazene, C12F8I2N2, have been synthesized and structurally characterized by single-crystal X-ray diffraction. The crystal structure of the non-iodinated homologue (E)-bis(2,3,5,6-tetrafluorophenyl)diazene, C12H2F8N2, is also reported. It is demonstrated that the studied halogen-bond donor molecule is a reliable tecton for assembling halogen-bonded co-crystals with potential photoresponsive behaviour. The azo group is not involved in any specific intermolecular interactions in any of the co-crystals studied, which is an interesting feature in the context of enhanced photoisomerization behaviour and photoactive properties of the material systems.

The15N NMR chemical shift in the characterization of weak halogen bonding in solution

2017 ◽  
Vol 203 ◽  
pp. 333-346 ◽  
Author(s):  
Sebastiaan B. Hakkert ◽  
Jürgen Gräfenstein ◽  
Mate Erdelyi
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shift ◽  
Halogen Bond ◽  
Molar Fraction ◽  
Halogen Bonding ◽  
Relative Strength ◽  
Lewis Base ◽  
Halogen Bonds ◽  
Bonded Complexes

We have studied the applicability of15N NMR spectroscopy in the characterization of the very weak halogen bonds of nonfluorinated halogen bond donors with a nitrogenous Lewis base in solution. The ability of the technique to detect the relative strength of iodine-, bromine- and chlorine-centered halogen bonds, as well as solvent and substituent effects was evaluated. Whereas computations on the DFT level indicate that15N NMR chemical shifts reflect the diamagnetic deshielding associated with the formation of a weak halogen bond, the experimentally observed chemical shift differences were on the edge of detectability due to the low molar fraction of halogen-bonded complexes in solution. The formation of the analogous yet stronger hydrogen bond of phenols have induced approximately ten times larger chemical shift changes, and could be detected and correlated to the electronic properties of substituents of the hydrogen bond donors. Overall,15N NMR is shown to be a suitable tool for the characterization of comparably strong secondary interactions in solution, but not sufficiently accurate for the detection of the formation of thermodynamically labile, weak halogen bonded complexes.

Anion Templated Crystal Engineering of Halogen Bonding Tripodal Tris(halopyridinium) Compounds

2020 ◽  
Author(s):  
Emer Foyle ◽  
Nicholas White
Keyword(s):  
Crystal Engineering ◽  
Self Assembly ◽  
Halogen Bond ◽  
Halogen Bonding ◽  
Halogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
H Nmr ◽  
Structural Database ◽  
Van Der Waals Radii

<div>In this work four new tripodal tris(halopyridinium) receptors containing potentially halogen</div><div>bonding groups were prepared. The ability of the receptors to bind anions in competitive</div><div>CD<sub>3</sub>CN/d<sub>6</sub>-DMSO was studied using <sup>1</sup>H NMR titration experiments, which revealed that the</div><div>receptors bind chloride anions more strongly than more basic acetate or other halide ions.</div><div>The solid state self–assembly of the tripodal receptors with halide anions was investigated by</div><div>X-ray crystallography. The nature of the structures was dependent on the choice of halide</div><div>anion, as well as the crystallisation solvent. Halogen bond lengths as short as 80% of the sum</div><div>of the van der Waals radii were observed, which is shorter than any halogen bonds involving</div><div>halopyridinium receptors in the Cambridge Structural Database.</div>

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