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Amide Coupling Reaction for the Synthesis of Bispyridine-based Ligands and Their Complexation to Platinum as Dinuclear Anticancer Agents
Published on: May 28, 2014
Pyridine-2,5-diamine.
Sergiu Draguta1, Victor N Khrustalev, Marina S Fonari
1D. Ghitu Institute of Electronic Engineering and Nanotechnologies, 3/3 Academy str., MD-2028 Chisinau, Moldova.
Acta Crystallographica. Section E, Structure Reports Online
|March 12, 2013
Summary
This study details the crystal structure of a molecule with formula C5H7N3. It reveals specific intra-cyclic angles and hydrogen bonding patterns that form a three-dimensional network in the crystal.
Area of Science:
- Crystallography
- Organic Chemistry
- Molecular Structure
Background:
- Understanding molecular geometry and intermolecular interactions is crucial in crystal engineering.
- Pyridine derivatives are important scaffolds in medicinal chemistry and materials science.
Purpose of the Study:
- To elucidate the crystal structure and hydrogen bonding network of the title molecule (C5H7N3).
- To analyze the intra-cyclic angles and the deviation of amino group nitrogen atoms from the pyridine plane.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the molecular and crystal structure.
- Analysis of bond lengths, bond angles, and intermolecular interactions (hydrogen bonds) was performed.
Main Results:
- The molecule C5H7N3 exhibits specific intra-cyclic angles ranging from 117.15(10)° to 124.03(11)°.
- Amino group nitrogen atoms show trigonal-pyramidal configurations with slight deviations from the pyridine plane.
- The crystal structure is characterized by N-H⋯N hydrogen bonds, forming centrosymmetric dimers and a 3D network.
Conclusions:
- The crystal packing of C5H7N3 is stabilized by both intra- and inter-molecular hydrogen bonding.
- The study provides detailed structural insights into this pyridine derivative and its hydrogen bonding capabilities.
Related Concept Videos
01:25Basicity of Heterocyclic Aromatic Amines
Heterocyclic amines, where the N atom is a part of an alicyclic system, are similar in basicity to alkylamines. Interestingly, the heterocyclic amine having a nitrogen atom as part of an aromatic ring has much less basicity than its corresponding alicyclic counterpart. For this reason, as presented in Figure 1, piperidine (pKb = 2.8) is significantly more basic than pyridine (pKb = 8.8).
01:10Nomenclature of Aryl and Heterocyclic Amines
The simplest aromatic amine is phenylamine, which contains an –NH2 functionality directly attached to an aromatic ring. The name aniline is designated for this skeleton. As shown in Figure 1, the common names of the functionalized anilines involve prefixes ortho-, meta-, and para- to indicate the substitution position. Different functionalized aniline derivatives also have notable trivial names.
01:17Nomenclature of Primary Amines
Primary, secondary, and tertiary amines are compounds consisting of one, two, and three alkyl groups connected to the amino group (–NH2), respectively. As depicted in Figure 1, the common name of the primary amines is obtained by adding the suffix -amine to the alkyl substituent attached to the amino group as the corresponding alkylamine.
01:19Diazonium Group Substitution: –OH and –H
Nitrous acid, a weak acid, is prepared in situ via the reaction of sodium nitrite with a strong acid under cold conditions. This nitrous acid prepared in situ reacts with primary arylamines to form arenediazonium salts. Such reactions are known as diazotization reactions. As shown in Figure 1, the formation of arenediazonium salts begins with the decomposition of nitrous acid in an acidic solution to give nitrosonium ions.
01:11Aryldiazonium Salts to Azo Dyes: Diazo Coupling
The reaction of weakly electrophilic aryldiazonium (also called arenediazonium) salts with highly activated aromatic compounds leads to the formation of products with an —N=N— link, called an azo linkage. This reaction, presented in Figure 1, is known as diazo coupling and occurs without the loss of the nitrogen atoms of the aryldiazonium salt. Highly activated aromatic compounds such as phenols or arylamines favor the diazo coupling reaction. The coupling generally occurs at the para position.
01:371° Amines to Diazonium or Aryldiazonium Salts: Diazotization with NaNO2 Mechanism
Nitrous acid is a relatively weak and unstable acid prepared in situ by the reaction of sodium nitrite and cold, dilute hydrochloric acid. In an acidic solution, the nitrous acid undergoes protonation when it loses water to form a nitrosonium ion—an electrophile. Nitrous acid reacts with primary amines to give diazonium salts. The reaction is called diazotization of primary amines.