Next Article in Journal
Coordination Networks Based on Boronate and Benzoxaborolate Ligands
Next Article in Special Issue
Comparisons between Crystallography Data and Theoretical Parameters and the Formation of Intramolecular Hydrogen Bonds: Benznidazole
Previous Article in Journal
Colloidal Crystallization in 2D for Short-Ranged Attractions: A Descriptive Overview
Previous Article in Special Issue
The Role of Hydrogen Bond in Designing Molecular Optical Materials
Article Menu

Export Article

Open AccessArticle
Crystals 2016, 6(4), 47; doi:10.3390/cryst6040047

The Hydrogen Bonded Structures of Two 5-Bromobarbituric Acids and Analysis of Unequal C5–X and C5–X′ Bond Lengths (X = X′ = F, Cl, Br or Me) in 5,5-Disubstituted Barbituric Acids

1
Institute of Pharmacy, University of Innsbruck, Innrain 52c, 6020 Innsbruck, Austria
2
Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 80, 6020 Innsbruck, Austria
*
Author to whom correspondence should be addressed.
Academic Editor: Sławomir J. Grabowski
Received: 15 December 2015 / Revised: 14 April 2016 / Accepted: 18 April 2016 / Published: 22 April 2016
(This article belongs to the Special Issue Analysis of Hydrogen Bonds in Crystals)
View Full-Text   |   Download PDF [4383 KB, uploaded 22 April 2016]   |  

Abstract

The crystal structure of the methanol hemisolvate of 5,5-dibromobarbituric acid (1MH) displays an H-bonded layer structure which is based on N–H∙∙∙O=C, N–H∙∙∙O(MeOH) and (MeOH)O–H∙∙∙O interactions. The barbiturate molecules form an H-bonded substructure which has the fes topology. 5,5′-Methanediylbis(5-bromobarbituric acid) 2, obtained from a solution of 5,5-dibromobarbituric acid in nitromethane, displays a N–H···O=C bonded framework of the sxd type. The conformation of the pyridmidine ring and the lengths of the ring substituent bonds C5–X and C5–X′ in crystal forms of 5,5-dibromobarbituric acid and three closely related analogues (X = X′ = Br, Cl, F, Me) have been investigated. In each case, a conformation close to a C5-endo envelope is correlated with a significant lengthening of the axial C5–X′ in comparison to the equatorial C5–X bond. Isolated molecule geometry optimizations at different levels of theory confirm that the C5-endo envelope is the global conformational energy minimum of 5,5-dihalogenbarbituric acids. The relative lengthening of the axial bond is therefore interpreted as an inherent feature of the preferred envelope conformation of the pyrimidine ring, which minimizes repulsive interactions between the axial substituent and pyrimidine ring atoms. View Full-Text
Keywords: crystal structure; hydrogen bond; topology; geometry optimization; barbiturates crystal structure; hydrogen bond; topology; geometry optimization; barbiturates
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Supplementary material

Scifeed alert for new publications

Never miss any articles matching your research from any publisher
  • Get alerts for new papers matching your research
  • Find out the new papers from selected authors
  • Updated daily for 49'000+ journals and 6000+ publishers
  • Define your Scifeed now

SciFeed Share & Cite This Article

MDPI and ACS Style

Gelbrich, T.; Braun, D.E.; Oberparleiter, S.; Schottenberger, H.; Griesser, U.J. The Hydrogen Bonded Structures of Two 5-Bromobarbituric Acids and Analysis of Unequal C5–X and C5–X′ Bond Lengths (X = X′ = F, Cl, Br or Me) in 5,5-Disubstituted Barbituric Acids. Crystals 2016, 6, 47.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Crystals EISSN 2073-4352 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top