scholarly journals Versatility of the Cyano Group in Intermolecular Interactions

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4495
Author(s):  
Steve Scheiner
Keyword(s):  
Intermolecular Interactions ◽  
Lewis Acid ◽  
Electrostatic Potential ◽  
Cyano Group ◽  
Acid Molecule ◽  
Cyclic System ◽  
Precise Nature ◽  
Noncovalent Bond ◽  
Positive Region ◽  
Cyano Groups

Several cyano groups are added to an alkane, alkene, and alkyne group so as to construct a Lewis acid molecule with a positive region of electrostatic potential in the area adjoining these substituents. Although each individual cyano group produces only a weak π-hole, when two or more such groups are properly situated, they can pool their π-holes into one much more intense positive region that is located midway between them. A NH3 base is attracted to this site, where it forms a strong noncovalent bond to the Lewis acid, amounting to as much as 13.6 kcal/mol. The precise nature of the bonding varies a bit from one complex to the next but typically contains a tetrel bond to the C atoms of the cyano groups or the C atoms of the linkage connecting the C≡N substituents. The placement of the cyano groups on a cyclic system like cyclopropane or cyclobutane has a mild weakening effect upon the binding. Although F is comparable to C≡N in terms of electron-withdrawing power, the replacement of cyano by F substituents substantially weakens the binding with NH3.

scholarly journals Convenient Access to Functionalized Non-Symmetrical Atropisomeric 4,4′-Bipyridines

Compounds ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 58-74
Author(s):  
Emmanuel Aubert ◽  
Emmanuel Wenger ◽  
Paola Peluso ◽  
Victor Mamane
Keyword(s):  
Solid State ◽  
Intermolecular Interactions ◽  
Medicinal Chemistry ◽  
Crystal Packing ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Halogen Bonds ◽  
Cross Coupling Reactions ◽  
Cyano Groups ◽  
Post Functionalization

Non-symmetrical chiral 4,4′-bipyridines have recently found interest in organocatalysis and medicinal chemistry. In this regard, the development of efficient methods for their synthesis is highly desirable. Herein, a series of non-symmetrical atropisomeric polyhalogenated 4,4′-bipyridines were prepared and further functionalized by using cross-coupling reactions. The desymmetrization step is based on the N-oxidation of one of the two pyridine rings of the 4,4′-bipyridine skeleton. The main advantage of this methodology is the possible post-functionalization of the pyridine N-oxide, allowing selective introduction of chlorine, bromine or cyano groups in 2- and 2′-postions of the chiral atropisomeric 4,4′-bipyridines. The crystal packing in the solid state of some newly prepared derivatives was analyzed and revealed the importance of halogen bonds in intermolecular interactions.

The Total Synthesis of Spermine Alkaloid Kukoamine Bimesylate

Synlett ◽  
2018 ◽  
Vol 29 (20) ◽  
pp. 2669-2672
Author(s):  
Kai Dong
Keyword(s):  
Total Synthesis ◽  
Michael Addition ◽  
Addition Reaction ◽  
Cyano Group ◽  
Michael Addition Reaction ◽  
Amino Groups ◽  
Competitive Reaction ◽  
12 Steps ◽  
Cyano Groups

The first total synthesis of kukoamine B bimesylate was completed from 1,4-diaminobutane dihydrochloride in 12 steps with a 11.4% overall yield, and all the steps could be carried out at a kilogram scale. The cyano groups were used as the precursor of amino groups to avoid the competitive reaction delicately. The aza-Michael addition reaction, amidation and hydrogenation of the cyano group sequence was streamlined as a general approach towards the synthesis of polyamine structures.

Directional Weak Intermolecular Interactions: σ-Hole Bonding

2010 ◽  
Vol 63 (12) ◽  
pp. 1598 ◽  
Author(s):  
Jane S. Murray ◽  
Kevin E. Riley ◽  
Peter Politzer ◽  
Timothy Clark
Keyword(s):  
Hydrogen Bonding ◽  
Intermolecular Interactions ◽  
Electrostatic Potential ◽  
Crystal Engineering ◽  
Molecular Electrostatic Potential ◽  
Weak Interactions ◽  
Halogen Bonding ◽  
Donor Atom ◽  
Weak Intermolecular Interactions ◽  
Special Case

The prototypical directional weak interactions, hydrogen bonding and σ-hole bonding (including the special case of halogen bonding) are reviewed in a united picture that depends on the anisotropic nature of the molecular electrostatic potential around the donor atom. Qualitative descriptions of the effects that lead to these anisotropic distributions are given and examples of the importance of σ-hole bonding in crystal engineering and biological systems are discussed.

Topological characterization of electron density, electrostatic potential and intermolecular interactions of 2-nitroimidazole: an experimental and theoretical study

2016 ◽  
Vol 72 (5) ◽  
pp. 775-786 ◽  
Author(s):  
Chinnasamy Kalaiarasi ◽  
Mysore S Pavan ◽  
Poomani Kumaradhas
Keyword(s):  
Electron Density ◽  
Intermolecular Interactions ◽  
Electrostatic Potential ◽  
Theoretical Calculations ◽  
Topological Analysis ◽  
X Ray Diffraction ◽  
Topological Characterization ◽  
Data Set ◽  
X Ray ◽  
Charge Concentration

An experimental charge density distribution of 2-nitroimidazole was determined from high-resolution X-ray diffraction and the Hansen–Coppens multipole model. The 2-nitroimidazole compound was crystallized and a high-angle X-ray diffraction intensity data set has been collected at low temperature (110 K). The structure was solved and further, an aspherical multipole model refinement was performed up to octapole level; the results were used to determine the structure, bond topological and electrostatic properties of the molecule. In the crystal, the molecule exhibits a planar structure and forms weak and strong intermolecular hydrogen-bonding interactions with the neighbouring molecules. The Hirshfeld surface of the molecule was plotted, which explores different types of intermolecular interactions and their strength. The topological analysis of electron density at the bond critical points (b.c.p.) of the molecule was performed, from that the electron density ρbcp(r) and the Laplacian of electron density ∇2ρbcp(r) at the b.c.p.s of the molecule have been determined; these parameters show the charge concentration/depletion of the nitroimidazole bonds in the crystal. The electrostatic parameters like atomic charges and the dipole moment of the molecule were calculated. The electrostatic potential surface of the molecule has been plotted, and it displays a large electronegative region around the nitro group. All the experimental results were compared with the corresponding theoretical calculations performed usingCRYSTAL09.

Effects of Complexation on the Glass Transition Temperature of Polymers

1990 ◽  
Vol 215 ◽  
Author(s):  
Michael F. Roberts ◽  
Samson A. Jenekhe
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Hydrogen Bonds ◽  
Intermolecular Interactions ◽  
Lewis Acid ◽  
Dominant Effect ◽  
Intermolecular Hydrogen Bonds ◽  
Aromatic Polyamides ◽  
Rigid Chain

AbstractThe effects of Lewis acid complexation on the glass transition temperature (Tg) of several polymers with strong intermolecular interactions was investigated. The decrease in the Tg due to GaCl3 complexation of aliphatic and aromatic polyamides was 40–600° C and 148° C, respectively, and was shown to originate from scission of the intermolecular hydrogen bonds. The reduction in the Tg due to GaCl3 complexation of rigid–chain polymers was greater that 325° C and can be explained by the mitigation of the otherwise strong van der Waals forces in the pristine polymers. Thus, the dominant effect of intermolecular interactions on the Tg of several polymers has been probed by Lewis acid complexation.

Experimental and theoretical analysis of lp⋯π intermolecular interactions in derivatives of 1,2,4-triazoles

CrystEngComm ◽  
2014 ◽  
Vol 16 (9) ◽  
pp. 1702-1713 ◽  
Author(s):  
Rahul Shukla ◽  
T. P. Mohan ◽  
B. Vishalakshi ◽  
Deepak Chopra
Keyword(s):  
Theoretical Analysis ◽  
Intermolecular Interactions ◽  
Electrostatic Potential ◽  
Π Interactions ◽  
Derivatives Of

The calculations performed on the evaluation of the electrostatic potential provide deeper insights into the nature of lp⋯π interactions.

scholarly journals Various Structural Types of Cyanide-Bridged FeIII–MnIII Bimetallic Coordination Polymers (CPs) and Polynuclear Clusters Based-on A New mer-Tricyanoiron(III)Building Block: Synthesis, Crystal Structures, and Magnetic Properties

Polymers ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1585
Author(s):  
Wenlong Lan ◽  
Xiaoyun Hao ◽  
Yong Dou ◽  
Zhen Zhou ◽  
Lu Yang ◽  
...  
Keyword(s):  
Cyano Group ◽  
Linear Chain ◽  
Magnetic Coupling ◽  
1D Chain ◽  
Structure Correlation ◽  
Cyano Groups ◽  
Coordinated Water ◽  
In Cis ◽  
Polynuclear Clusters ◽  
Base Compound

Four cyanide-bridged FeIII–MnIII complexes {[Fe(qxcq)(CN)3][Mn(L1)(H2O)]}[Mn(L1)(H2O)(CH3OH)](ClO4)·1.5MeOH·0.5H2O (L1 = N,N′-bis(3-methoxy-5-bromosalicylideneiminate) (2), {[Fe(qxcq)(CN)3][Mn(L2)]}2·0.5H2O (L2 = N,N′-ethylene-bis(3-ethoxysalicylideneiminate)) (3), [Fe(qxcq)(CN)3][Mn(L3)] (L3 = bis(acetylacetonato)ethylenediimine) (4), [Fe(qxcq)(CN)3][Mn(L4)]·1.5MeOH·0.5CH3CN·0.25H2O (L4 = N,N′-(1,1,2,2-tetramethylethylene)bis(salicylideneiminate)) (5), were prepared by assembling a new structurally characterized mer-tricyanoiron(III) molecular precursor (Ph4P)[Fe(qxcq)(CN)3]·0.5H2O (qxcq− = 8-(2-quinoxaline-2-carboxamido)quinoline anion) (1) and the corresponding manganese(III) Schiff base compound. Complexes 2and 3containa cyanide-bridged heterobimetallic dinuclear entity, which can be further dimerized by self-complementary H-bond interactions through the coordinated water molecule from one complex and the free O4unit from the adjacent complex. Complexes 4 and 5 area one-dimensional coordination polymer (CP) comprised of the repeated [Mn(Schiffbase)-Fe(qxcq)(CN)3] units. Complex 4 shows a linear-chain conformation with two trans-located cyano groups bridgingthe neighboring Mn units, while complex 5 is a zigzag-like 1D CP, where the two cyano groups in cis configurationfunction as bridges. In bothcomplexes 4 and 5, the inter-chain π–πstack interactions within the aromaticrings of cyanide precursor extend the 1D chain into the supermolecular 2D networks. The magnetic property has been experimentally studied and theoretically fitted over the four Fe(III)-Mn(III) complexes, revealing the antiferromagnetic interaction in complexes 2 and 4 and the unusual ferromagnetic coupling in complexes 3 and 5 between the Fe(III) ion and the Mn(III) ion bridged by the cyano group. Furthermore, the different magnetic coupling nature has been analyzed on the basis of the magneto-structure correlation of the mer-tricyanometallate-based Fe(III)-Mn(III) magnetic system.

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